draft-ietf-idr-ls-distribution-02.txt   draft-ietf-idr-ls-distribution-03.txt 
Inter-Domain Routing H. Gredler Inter-Domain Routing H. Gredler
Internet-Draft Juniper Networks, Inc. Internet-Draft Juniper Networks, Inc.
Intended status: Standards Track J. Medved Intended status: Standards Track J. Medved
Expires: August 28, 2013 S. Previdi Expires: November 22, 2013 S. Previdi
Cisco Systems, Inc. Cisco Systems, Inc.
A. Farrel A. Farrel
Juniper Networks, Inc. Juniper Networks, Inc.
S. Ray S. Ray
Cisco Systems, Inc. Cisco Systems, Inc.
February 24, 2013 May 21, 2013
North-Bound Distribution of Link-State and TE Information using BGP North-Bound Distribution of Link-State and TE Information using BGP
draft-ietf-idr-ls-distribution-02 draft-ietf-idr-ls-distribution-03
Abstract Abstract
In a number of environments, a component external to a network is In a number of environments, a component external to a network is
called upon to perform computations based on the network topology and called upon to perform computations based on the network topology and
current state of the connections within the network, including current state of the connections within the network, including
traffic engineering information. This is information typically traffic engineering information. This is information typically
distributed by IGP routing protocols within the network distributed by IGP routing protocols within the network
This document describes a mechanism by which links state and traffic This document describes a mechanism by which links state and traffic
engineering information can be collected from networks and shared engineering information can be collected from networks and shared
with external components using the BGP routing protocol. This is with external components using the BGP routing protocol. This is
achieved using a new BGP Network Layer Reachability Information achieved using a new BGP Network Layer Reachability Information
(NLRI) encoding format. The mechanism is applicable to physical and (NLRI) encoding format. The mechanism is applicable to physical and
virtual links. The mechanism described is subject to policy control. virtual IGP links. The mechanism described is subject to policy
control.
Applications of this technique include Application Layer Traffic Applications of this technique include Application Layer Traffic
Optimization (ALTO) servers, and Path Computation Elements (PCEs). Optimization (ALTO) servers, and Path Computation Elements (PCEs).
Requirements Language Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
skipping to change at page 2, line 10 skipping to change at page 2, line 11
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
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Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 28, 2013. This Internet-Draft will expire on November 22, 2013.
Copyright Notice Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Provisions Relating to IETF Documents Provisions Relating to IETF Documents
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5
2. Motivation and Applicability . . . . . . . . . . . . . . . . . 5 2. Motivation and Applicability . . . . . . . . . . . . . . . . . 6
2.1. MPLS-TE with PCE . . . . . . . . . . . . . . . . . . . . . 5 2.1. MPLS-TE with PCE . . . . . . . . . . . . . . . . . . . . . 6
2.2. ALTO Server Network API . . . . . . . . . . . . . . . . . 7 2.2. ALTO Server Network API . . . . . . . . . . . . . . . . . 8
3. Carrying Link State Information in BGP . . . . . . . . . . . . 8 3. Carrying Link State Information in BGP . . . . . . . . . . . . 9
3.1. TLV Format . . . . . . . . . . . . . . . . . . . . . . . . 8 3.1. TLV Format . . . . . . . . . . . . . . . . . . . . . . . . 9
3.2. The Link State NLRI . . . . . . . . . . . . . . . . . . . 9 3.2. The Link State NLRI . . . . . . . . . . . . . . . . . . . 10
3.2.1. Identifier TLV . . . . . . . . . . . . . . . . . . . . 12 3.2.1. Node Descriptors . . . . . . . . . . . . . . . . . . . 13
3.2.2. Node Descriptors . . . . . . . . . . . . . . . . . . . 14 3.2.2. Link Descriptors . . . . . . . . . . . . . . . . . . . 17
3.2.3. Link Descriptors . . . . . . . . . . . . . . . . . . . 22 3.2.3. Prefix Descriptors . . . . . . . . . . . . . . . . . . 18
3.2.4. Prefix Descriptors . . . . . . . . . . . . . . . . . . 23 3.3. The LINK_STATE Attribute . . . . . . . . . . . . . . . . . 20
3.3. The LINK_STATE Attribute . . . . . . . . . . . . . . . . . 23 3.3.1. Node Attribute TLVs . . . . . . . . . . . . . . . . . 20
3.3.1. Link Attribute TLVs . . . . . . . . . . . . . . . . . 24 3.3.2. Link Attribute TLVs . . . . . . . . . . . . . . . . . 23
3.3.2. Node Attribute TLVs . . . . . . . . . . . . . . . . . 27 3.3.3. Prefix Attribute TLVs . . . . . . . . . . . . . . . . 27
3.3.3. Prefix Attributes TLVs . . . . . . . . . . . . . . . . 29 3.4. BGP Next Hop Information . . . . . . . . . . . . . . . . . 30
3.4. BGP Next Hop Information . . . . . . . . . . . . . . . . . 33 3.5. Inter-AS Links . . . . . . . . . . . . . . . . . . . . . . 31
3.5. Inter-AS Links . . . . . . . . . . . . . . . . . . . . . . 33 3.6. Router-ID Anchoring Example: ISO Pseudonode . . . . . . . 31
4. Link to Path Aggregation . . . . . . . . . . . . . . . . . . . 33 3.7. Router-ID Anchoring Example: OSPFv2 to IS-IS Migration . . 32
4.1. Example: No Link Aggregation . . . . . . . . . . . . . . . 34 4. Link to Path Aggregation . . . . . . . . . . . . . . . . . . . 32
4.2. Example: ASBR to ASBR Path Aggregation . . . . . . . . . . 34 4.1. Example: No Link Aggregation . . . . . . . . . . . . . . . 33
4.3. Example: Multi-AS Path Aggregation . . . . . . . . . . . . 35 4.2. Example: ASBR to ASBR Path Aggregation . . . . . . . . . . 33
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 35 4.3. Example: Multi-AS Path Aggregation . . . . . . . . . . . . 34
6. Manageability Considerations . . . . . . . . . . . . . . . . . 35 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 34
6. Manageability Considerations . . . . . . . . . . . . . . . . . 34
6.1. Operational Considerations . . . . . . . . . . . . . . . . 35 6.1. Operational Considerations . . . . . . . . . . . . . . . . 35
6.1.1. Operations . . . . . . . . . . . . . . . . . . . . . . 36 6.1.1. Operations . . . . . . . . . . . . . . . . . . . . . . 35
6.1.2. Installation and Initial Setup . . . . . . . . . . . . 36 6.1.2. Installation and Initial Setup . . . . . . . . . . . . 35
6.1.3. Migration Path . . . . . . . . . . . . . . . . . . . . 36 6.1.3. Migration Path . . . . . . . . . . . . . . . . . . . . 35
6.1.4. Requirements on Other Protocols and Functional 6.1.4. Requirements on Other Protocols and Functional
Components . . . . . . . . . . . . . . . . . . . . . . 36 Components . . . . . . . . . . . . . . . . . . . . . . 35
6.1.5. Impact on Network Operation . . . . . . . . . . . . . 36 6.1.5. Impact on Network Operation . . . . . . . . . . . . . 35
6.1.6. Verifying Correct Operation . . . . . . . . . . . . . 37 6.1.6. Verifying Correct Operation . . . . . . . . . . . . . 36
6.2. Management Considerations . . . . . . . . . . . . . . . . 37 6.2. Management Considerations . . . . . . . . . . . . . . . . 36
6.2.1. Management Information . . . . . . . . . . . . . . . . 37 6.2.1. Management Information . . . . . . . . . . . . . . . . 36
6.2.2. Fault Management . . . . . . . . . . . . . . . . . . . 37 6.2.2. Fault Management . . . . . . . . . . . . . . . . . . . 36
6.2.3. Configuration Management . . . . . . . . . . . . . . . 37 6.2.3. Configuration Management . . . . . . . . . . . . . . . 36
6.2.4. Accounting Management . . . . . . . . . . . . . . . . 37 6.2.4. Accounting Management . . . . . . . . . . . . . . . . 36
6.2.5. Performance Management . . . . . . . . . . . . . . . . 37 6.2.5. Performance Management . . . . . . . . . . . . . . . . 36
6.2.6. Security Management . . . . . . . . . . . . . . . . . 38 6.2.6. Security Management . . . . . . . . . . . . . . . . . 37
7. TLV/SubTLV Code Points Summary . . . . . . . . . . . . . . . . 38 7. TLV/Sub-TLV Code Points Summary . . . . . . . . . . . . . . . 37
8. Security Considerations . . . . . . . . . . . . . . . . . . . 40 8. Security Considerations . . . . . . . . . . . . . . . . . . . 39
9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 40 9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 39
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 40 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 39
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 40 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 40
11.1. Normative References . . . . . . . . . . . . . . . . . . . 40 11.1. Normative References . . . . . . . . . . . . . . . . . . . 40
11.2. Informative References . . . . . . . . . . . . . . . . . . 42 11.2. Informative References . . . . . . . . . . . . . . . . . . 41
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 43
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 42
1. Introduction 1. Introduction
The contents of a Link State Database (LSDB) or a Traffic Engineering The contents of a Link State Database (LSDB) or a Traffic Engineering
Database (TED) has the scope of an IGP area. Some applications, such Database (TED) has the scope of an IGP area. Some applications, such
as end-to-end Traffic Engineering (TE), would benefit from visibility as end-to-end Traffic Engineering (TE), would benefit from visibility
outside one area or Autonomous System (AS) in order to make better outside one area or Autonomous System (AS) in order to make better
decisions. decisions.
The IETF has defined the Path Computation Element (PCE) [RFC4655] as The IETF has defined the Path Computation Element (PCE) [RFC4655] as
a mechanism for achieving the computation of end-to-end TE paths that a mechanism for achieving the computation of end-to-end TE paths that
cross the visibility of more than one TED or which require CPU- cross the visibility of more than one TED or which require CPU-
intensive or coordinated computations. The IETF has also defined the intensive or coordinated computations. The IETF has also defined the
ALTO Server [RFC5693] as an entity that generates an abstracted ALTO Server [RFC5693] as an entity that generates an abstracted
network topology and provides it to network-aware applications. network topology and provides it to network-aware applications.
Both a PCE and an ALTO Server need to gather information about the Both a PCE and an ALTO Server need to gather information about the
topologies and capabilities of the network in order to be able to topologies and capabilities of the network in order to be able to
fulfill their function fulfill their function.
This document describes a mechanism by which Link State and TE This document describes a mechanism by which Link State and TE
information can be collected from networks and shared with external information can be collected from networks and shared with external
components using the BGP routing protocol [RFC4271]. This is components using the BGP routing protocol [RFC4271]. This is
achieved using a new BGP Network Layer Reachability Information achieved using a new BGP Network Layer Reachability Information
(NLRI) encoding format. The mechanism is applicable to physical and (NLRI) encoding format. The mechanism is applicable to physical and
virtual links. The mechanism described is subject to policy control. virtual links. The mechanism described is subject to policy control.
A router maintains one or more databases for storing link-state A router maintains one or more databases for storing link-state
information about nodes and links in any given area. Link attributes information about nodes and links in any given area. Link attributes
skipping to change at page 5, line 43 skipping to change at page 6, line 43
routers in a POP. Abstracted topology can also be a mix of physical routers in a POP. Abstracted topology can also be a mix of physical
and virtual nodes and physical and virtual links. Furthermore, the and virtual nodes and physical and virtual links. Furthermore, the
BGP Speaker can apply policy to determine when information is updated BGP Speaker can apply policy to determine when information is updated
to the consumer so that there is reduction of information flow form to the consumer so that there is reduction of information flow form
the network to the consumers. Mechanisms through which topologies the network to the consumers. Mechanisms through which topologies
can be aggregated or virtualized are outside the scope of this can be aggregated or virtualized are outside the scope of this
document document
2. Motivation and Applicability 2. Motivation and Applicability
This section describes uses cases from which the requirements can be This section describes use cases from which the requirements can be
derived. derived.
2.1. MPLS-TE with PCE 2.1. MPLS-TE with PCE
As described in [RFC4655] a PCE can be used to compute MPLS-TE paths As described in [RFC4655] a PCE can be used to compute MPLS-TE paths
within a "domain" (such as an IGP area) or across multiple domains within a "domain" (such as an IGP area) or across multiple domains
(such as a multi-area AS, or multiple ASes). (such as a multi-area AS, or multiple ASes).
o Within a single area, the PCE offers enhanced computational power o Within a single area, the PCE offers enhanced computational power
that may not be available on individual routers, sophisticated that may not be available on individual routers, sophisticated
skipping to change at page 8, line 28 skipping to change at page 9, line 28
+--------+ | +--------+ |
| Client |<--+ | Client |<--+
+--------+ +--------+
Figure 3: ALTO Server using network topology information Figure 3: ALTO Server using network topology information
3. Carrying Link State Information in BGP 3. Carrying Link State Information in BGP
This specification contains two parts: definition of a new BGP NLRI This specification contains two parts: definition of a new BGP NLRI
that describes links, nodes and prefixes comprising IGP link state that describes links, nodes and prefixes comprising IGP link state
information, and definition of a new BGP path attribute that carries information, and definition of a new BGP path attribute (BGP-LS
link, node and prefix properties and attributes, such as the link and attribute) that carries link, node and prefix properties and
prefix metric or node properties. attributes, such as the link and prefix metric or auxiliary Router-
IDs of nodes, etc.
3.1. TLV Format 3.1. TLV Format
Information in the new link state NLRIs and attributes is encoded in Information in the new link state NLRIs and attributes is encoded in
Type/Length/Value triplets. The TLV format is shown in Figure 4. Type/Length/Value triplets. The TLV format is shown in Figure 4.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | // Value (variable) //
| Value (variable) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: TLV format Figure 4: TLV format
The Length field defines the length of the value portion in octets The Length field defines the length of the value portion in octets
(thus a TLV with no value portion would have a length of zero). The (thus a TLV with no value portion would have a length of zero). The
TLV is not padded to four-octet alignment. Unrecognized types are TLV is not padded to four-octet alignment. Unrecognized types are
ignored. preserved and propagated. In order to compare NLRIs with unknown
TLVs all TLVs MUST be ordered in ascending order. If there are more
TLVs of the same type, then the TLVs MUST be ordered in ascending
order of the TLV value within the set of TLVs with the same type.
All TLVs that are not specified as mandatory are considered optional.
3.2. The Link State NLRI 3.2. The Link State NLRI
The MP_REACH and MP_UNREACH attributes are BGP's containers for The MP_REACH and MP_UNREACH attributes are BGP's containers for
carrying opaque information. Each Link State NLRI describes either a carrying opaque information. Each Link State NLRI describes either a
node, a link or a prefix. node, a link or a prefix.
All link, node and prefix information SHALL be encoded using a TBD All non-VPN link, node and prefix information SHALL be encoded using
AFI / TBD SAFI header into those attributes. AFI 16388 / SAFI 71. VPN link, node and prefix information SHALL be
encoded using AFI 16388 / SAFI 128.
In order for two BGP speakers to exchange Link-State NLRI, they MUST In order for two BGP speakers to exchange Link-State NLRI, they MUST
use BGP Capabilities Advertisement to ensure that they both are use BGP Capabilities Advertisement to ensure that they both are
capable of properly processing such NLRI. This is done as specified capable of properly processing such NLRI. This is done as specified
in [RFC4760], by using capability code 1 (multi-protocol BGP), with in [RFC4760], by using capability code 1 (multi-protocol BGP), with
an AFI/SAFI TBD. an AFI 16388 / SAFI 71 and AFI 16388 / SAFI 128 for the VPN flavor.
The format of the Link State NLRI is shown in the following figure. The format of the Link State NLRI is shown in the following figure.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NLRI Type | Total NLRI Length | | NLRI Type | Total NLRI Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| Link-State NLRI (variable) | // Link-State NLRI (variable) //
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: Link State SAFI (TBD) NLRI Format Figure 5: Link State AFI 16388 / SAFI 71 NLRI Format
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NLRI Type | Total NLRI Length | | NLRI Type | Total NLRI Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ Route Distinguisher + + Route Distinguisher +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| Link-State NLRI (variable) | // Link-State NLRI (variable) //
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: Link State SAFI 128 NLRI Format Figure 6: Link State VPN AFI 16388 / SAFI 128 NLRI Format
The 'Total NLRI Length' field contains the cumulative length of rest The 'Total NLRI Length' field contains the cumulative length, in
of the NLRI not including the NLRI Type field or itself. For VPN octets, of rest of the NLRI not including the NLRI Type field or
applications it also includes the length of the Route Distinguisher. itself. For VPN applications it also includes the length of the
Route Distinguisher.
The 'NLRI Type' field can contain one of the following values: The 'NLRI Type' field can contain one of the following values:
Type = 1: Link NLRI, contains link descriptors and link attributes Type = 1: Node NLRI
Type = 2: Node NLRI, contains node attributes Type = 2: Link NLRI
Type = 3: IPv4 Topology Prefix NLRI Type = 3: IPv4 Topology Prefix NLRI
Type = 4: IPv6 Topology Prefix NLRI Type = 4: IPv6 Topology Prefix NLRI
The Link NLRI (NLRI Type = 1) is shown in the following figure. The Node NLRI (NLRI Type = 1) is shown in the following figure.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+
| Protocol-ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Protocol-ID | Reserved | | | Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | (64 bits) |
| Identifier (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local Node Descriptors (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote Node Descriptors (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Descriptors (variable) | // Local Node Descriptors (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7: The Link NLRI format Figure 7: The Node NLRI format
The Node NLRI (NLRI Type = 2) is shown in the following figure. The Link NLRI (NLRI Type = 2) is shown in the following figure.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+
| Protocol-ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Protocol-ID | Reserved | | | Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | (64 bits) |
| Identifier (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local Node Descriptors (variable) | // Local Node Descriptors (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Remote Node Descriptors (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Link Descriptors (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 8: The Node NLRI format Figure 8: The Link NLRI format
The IPv4 and IPv6 Prefix NLRIs (NLRI Type = 3 and Type = 4) use the The IPv4 and IPv6 Prefix NLRIs (NLRI Type = 3 and Type = 4) use the
same format as shown in the following figure. same format as shown in the following figure.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+
| Protocol-ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Protocol-ID | Reserved | | | Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | (64 bits) |
| Identifier (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local Node Descriptor (variable) | // Local Node Descriptor (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reachability information (variable; one or more prefixes) | // Prefix Descriptors (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 9: The IPv4/IPv6 Topology Prefix NLRI format Figure 9: The IPv4/IPv6 Topology Prefix NLRI format
The 'Protocol-ID' field can contain one of the following values: The 'Protocol-ID' field can contain one of the following values:
Protocol-ID = 0: Unknown, The source of NLRI information could not Protocol-ID = 0: Unknown, The source of NLRI information could not
be determined be determined
Protocol-ID = 1: IS-IS Level 1, The NLRI information has been Protocol-ID = 1: IS-IS Level 1, The NLRI information has been
skipping to change at page 11, line 40 skipping to change at page 13, line 14
Protocol-ID = 3: OSPF, The NLRI information has been sourced by Protocol-ID = 3: OSPF, The NLRI information has been sourced by
OSPF OSPF
Protocol-ID = 4: Direct, The NLRI information has been sourced Protocol-ID = 4: Direct, The NLRI information has been sourced
from local interface state from local interface state
Protocol-ID = 5: Static, The NLRI information has been sourced by Protocol-ID = 5: Static, The NLRI information has been sourced by
static configuration static configuration
Both OSPF and IS-IS may run multiple routing protocol instances over Both OSPF and IS-IS may run multiple routing protocol instances over
the same link. See [RFC6822] and [RFC6549]. the same link. See [RFC6822] and [RFC6549]. These instances define
independent "routing universes". The 64-Bit 'Identifier' field is
Identifier TLV is a mandatory TLV containing identifiers of the NLRI used to identify the "routing universe" where the NLRI belongs. The
and used to associate the NLRI to an instance, a domain, an area or a NLRIs representing IGP objects (nodes, links or prefixes) from the
prefix. same routing universe MUST have the same 'Identifier' value; NLRIs
with different 'Identifier' values MUST be considered to be from
Each Node Descriptor and Link Descriptor consists of one or more TLVs different routing universes. Table Table 1 lists the 'Identifier'
described in the following sections. The sender of an UPDATE message values that are defined as well-known in this draft.
MUST order the TLVs within a Node Descriptor or a Link Descriptor in
ascending order of TLV type.
3.2.1. Identifier TLV
Identifier TLV (Type 256) is a mandatory TLV that appear in Node,
Link and Prefix NLRIs. Identifier TLV carries all identifiers
associated with the NLRI in a SubTLV format. Possible Sub TLVs are
Instance Identifier, Domain Identifier, Area Identifier, OSPF Route
Type and Multi-Topology ID.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identifier Sub-TLVs (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where:
Type: 256
Length: variable
Identifier Sub-TLVs: Identifiers
Figure 10: Identifier TLV Format
An Identifier may be used to distinguish a Node, a Link or a Prefix
with different types of identifiers. Therefore different SubTLVs are
defined here below in order to address the different requirements.
3.2.1.1. Instance Identifier SubTLV
Instance Identifier is a mandatory SubTLV that MUST be present in all
NLRIs. It is used to identify the topology instance the content of
the NLRI and attributes refers to.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Instance Identifier (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where:
Type: 1
Length: variable
Figure 11: Instance Identifier Sub-TLV Format
3.2.1.2. Domain Identifier SubTLV
Domain Identifier is an optional SubTLV that MAY be present in all
NLRIs. It is used to identify the domain (or sub-domain) to which
the NLRI belongs.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Domain Identifier (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where:
Type: 2
Length: variable
Figure 12: Domain Identifier Sub-TLV Format
3.2.1.3. Area Identifier SubTLV
Area Identifier is an optional SubTLV that MAY be present in all
NLRIs. It is used to identify the area to which the NLRI belongs.
Example: an OSPF ABR router advertises itself multiple time (one for
each area it participates into). Area Identifier allows the
different NLRIs of the same router to be discriminated.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Area Identifier (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where:
Type: 3
Length:variable
Figure 13: Area Identifier Sub-TLV Format
3.2.1.4. OSPF Route Type SubTLV
Route Type is an optional SubTLV that MAY be present in the Prefix
NLRIs. It is used to identify the OSPF route-type of the prefix. It
is used when an OSPF prefix is advertised in the OSPF domain with
multiple different route-types. The Route Type Identifier allows to
discriminate these advertisements.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Route Type |
+-+-+-+-+-+-+-+-+
Where: +------------+---------------------+
| Identifier | Routing Universe |
+------------+---------------------+
| 0 | L3 packet topology |
| 1 | L1 optical topology |
+------------+---------------------+
Type: 4 Table 1: Well-known Instance Identifiers
Length: 1
Figure 14: OSPF Route Type Sub-TLV Format Each Node Descriptor and Link Descriptor consists of one or more TLVs
described in the following sections.
OSPF Route Type can be either: Intra-Area (0x1), Inter-Area (0x2), 3.2.1. Node Descriptors
External 1 (0x3), External 2 (0x4), NSSA (0x5) and is encoded in a 3
bits number. For prefixes learned from IS-IS, this field MUST to be
set to 0x0 on transmission.
3.2.1.5. Multi Topology ID SubTLV Each link is anchored by a pair of Router-IDs that are used by the
underlying IGP, namely, 48 Bit ISO System-ID for IS-IS and 32 bit
Router-ID for OSPFv2 and OSPFv3. An IGP may use one or more
additional auxiliary Router-IDs, mainly for traffic engineering
purposes. For example, IS-IS may have one or more IPv4 and IPv6 TE
Router-IDs [RFC5305], [RFC6119]. These auxiliary Router-IDs MUST be
included in the link attribute described in Section Section 3.3.2.
The Multi Topology ID SubTLV (type: 5) carries the Multi Topology ID It is desirable that the Router-ID assignments inside the Node
for the link, node or prefix. The semantics of the Multi Topology ID Descriptor are globally unique. However there may be Router-ID
are defined in RFC5120, Section 7.2 [RFC5120], and the OSPF Multi spaces (e.g. ISO) where no global registry exists, or worse, Router-
Topology ID), defined in RFC4915, Section 3.7 [RFC4915]. If the IDs have been allocated following private-IP RFC 1918 [RFC1918]
value in the Multi Topology ID TLV is derived from OSPF, then the allocation. We use Autonomous System (AS) Number and BGP-LS
upper 9 bits of the Multi Topology ID are set to 0. Identifier in order to disambiguate the Router-IDs, as described in
Section 3.2.1.1.
0 1 2 3 3.2.1.1. Globally Unique Node/Link/Prefix Identifiers
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|R R R R| Multi Topology ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 15: Multi Topology ID SubTLV format One problem that needs to be addressed is the ability to identify an
IGP node globally (by "global", we mean within the BGP-LS database
collected by all BGP-LS speakers that talk to each other). This can
be expressed through the following two requirements:
The Multi Topology Identifier SubTLV is present in any NLRI Type. (A) The same node must not be represented by two keys (otherwise one
node will look like two nodes).
3.2.2. Node Descriptors (B) Two different nodes must not be represented by the same key
(otherwise, two nodes will look like one node).
Each link gets anchored by at least a pair of router-IDs. Since We define an "IGP domain" to be the set of nodes (hence, by extension
there are many Router-IDs formats (32 Bit IPv4 router-ID, 56 Bit ISO links and prefixes), within which, each node has a unique IGP
Node-ID and 128 Bit IPv6 router-ID) a link may be anchored by more representation by using the combination of Area-ID, Router-ID,
than one Router-ID pair. The set of Local and Remote Node Protocol, Topology-ID, and Instance ID. The problem is that BGP may
Descriptors describe which Protocols Router-IDs will be following to receive node/link/prefix information from multiple independent "IGP
"anchor" the link described by the "Link attribute TLVs". There must domains" and we need to distinguish between them. Moreover, we can't
be at least one "like" router-ID pair of a Local Node Descriptors and assume there is always one and only one IGP domain per AS. During
a Remote Node Descriptors per-protocol. If a peer sends an illegal IGP transitions it may happen that two redundant IGPs are in place.
combination in this respect, then this is handled as an NLRI error,
described in [RFC4760].
It is desirable that the Router-ID assignments inside the Node anchor In section Section 3.2.1.4 a set of sub-TLVs is described, which
are globally unique. However there may be router-ID spaces (e.g. allows to specify a flexible key for any given Node/Link information
ISO) where not even a global registry exists, or worse, Router-IDs such that global uniqueness of the NLRI is ensured.
have been allocated following private-IP RFC 1918 [RFC1918]
allocation. We use AS Number (or Confederation ID) and BGP
Identifier in order to disambiguate the Router-IDs, as described in
Section 3.2.2.4.
3.2.2.1. Local Node Descriptors 3.2.1.2. Local Node Descriptors
The Local Node Descriptors TLV (Type 257) contains Node Descriptors The Local Node Descriptors TLV contains Node Descriptors for the node
for the node anchoring the local end of the link. The length of this anchoring the local end of the link. This is a mandatory TLV in all
TLV is variable. The value contains one or more Node Descriptor Sub- three types of NLRIs. The length of this TLV is variable. The value
TLVs defined in Section 3.2.2.3. contains one or more Node Descriptor Sub-TLVs defined in
Section 3.2.1.4.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| Node Descriptor Sub-TLVs (variable) | // Node Descriptor Sub-TLVs (variable) //
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 16: Local Node Descriptors TLV format Figure 10: Local Node Descriptors TLV format
3.2.2.2. Remote Node Descriptors 3.2.1.3. Remote Node Descriptors
The Remote Node Descriptors TLV (Type 258) contains Node Descriptors The Remote Node Descriptors contains Node Descriptors for the node
for the node anchoring the remote end of the link. The length of anchoring the remote end of the link. This is a mandatory TLV for
this TLV is variable. The value contains one or more Node Descriptor link NLRIs. The length of this TLV is variable. The value contains
Sub-TLVs defined in Section 3.2.2.3. one or more Node Descriptor Sub-TLVs defined in Section 3.2.1.4.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| Node Descriptor Sub-TLVs (variable) | // Node Descriptor Sub-TLVs (variable) //
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 17: Remote Node Descriptors TLV format Figure 11: Remote Node Descriptors TLV format
3.2.2.3. Node Descriptor Sub-TLVs 3.2.1.4. Node Descriptor Sub-TLVs
The Node Descriptor Sub-TLV type codepoints and lengths are listed in The Node Descriptor Sub-TLV type codepoints and lengths are listed in
the following table: the following table:
+------------+-------------------+----------+ +--------------------+-------------------+----------+
| TLV/SubTLV | Description | Length | | Sub-TLV Code Point | Description | Length |
+------------+-------------------+----------+ +--------------------+-------------------+----------+
| 259 | Autonomous System | 4 | | 512 | Autonomous System | 4 |
| 260 | BGP Identifier | 4 | | 513 | BGP-LS Identifier | 4 |
| 261 | ISO Node-ID | 7 | | 514 | Area-ID | 4 |
| 262 | IPv4 Router-ID | variable | | 515 | IGP Router-ID | Variable |
| 263 | IPv6 Router-ID | 16 | +--------------------+-------------------+----------+
+------------+-------------------+----------+
Table 1: Node Descriptor Sub-TLVs Table 2: Node Descriptor Sub-TLVs
The TLV values in Node Descriptor Sub-TLVs are defined as follows: The sub-TLV values in Node Descriptor TLVs are defined as follows:
Autonomous System: opaque value (32 Bit AS Number) Autonomous System: opaque value (32 Bit AS Number)
BGP-Identifier: opaque value (32 Bit AS ID); uniquely identifying BGP-LS Identifier: opaque value (32 Bit ID). In conjunction with
the BGP-LS speaker within an AS. ASN, uniquely identifies the BGP-LS domain. The combination of
ASN and BGP-LS ID MUST be globally unique. All BGP-LS speakers
IPv4 Router ID: opaque value (can be an IPv4 address or an 32 Bit within an IGP flooding-set (set of IGP nodes within which an LSP/
router ID). When encoding an OSPF Designated Router ID, the LSA is flooded) MUST use the same ASN, BGP-LS ID tuple. If an IGP
length is 8 (first 4 bytes is the Router-ID originating the Type-2 domain consists of multiple flooding-sets, then all BGP-LS
LSA and next 4 bytes are taken from the Type-2 LSA ID). In other speakers within the IGP domain SHOULD use the same ASN, BGP-LS ID
cases, the length is 4. tuple. The ASN, BGP Router-ID tuple (which is globally unique
[RFC6286] ) of one of the BGP-LS speakers within the flooding-set
IPv6 Router ID: opaque value (can be an IPv6 address or 128 Bit (or IGP domain) may be used for all BGP-LS speakers in that
router ID). flooding-set (or IGP domain).
ISO Node ID: ISO node-ID (6 octets ISO system-ID) followed by a PSN
octet in case LAN "Pseudonode" information gets advertised. The
PSN octet must be zero for non-LAN "Pseudonodes".
There can be at most one instance of each TLV type present in any
Node Descriptor. The TLV ordering within a Node descriptor MUST
be kept in order of increasing numeric value of type. TLVs 259
and 260 specify administrative context in which TLVs 261-263 are
to be evaluated. The first TLV from range 261-263 is to be
interpreted as the primary node identifier by which the node can
be referenced within its administrative contexts. Any further
TLVs are to be treated as secondary identifiers, which may be used
for cross-reference, but are to be treated as if they are object
attributes.
3.2.2.4. Globally Unique BGP-LS Identifiers
One problem that needs to be addressed is the ability to identify an
IGP node globally (by "global", we mean within the BGP-LS database
collected by all BGP-LS speakers that talk to each other). This can
be expressed through the following two requirements:
(A) The same node must not be represented by two keys (otherwise one
node will look like two nodes).
(B) Two different nodes must not be represented by the same key
(otherwise, two nodes will look like one node).
We define an "IGP domain" to be the set of nodes (and links), within
which, each node has a unique IGP representation by using the
combination of area-id, IGP router-id, Level, instance ID, etc. The
problem is that BGP brings nodes from multiple independent "IGP
domains" and we need to distinguish between them. Moreover, we can't
assume there is always one and only one IGP domain per Autonomous
System (or Autonomous System confederation member). Following cases
illustrate scenario's where IGP domain and ASs boundaries do not
match.
(i) Stub ASs or non-contiguous AS: One can have an AS that has Area ID: It is used to identify the 32 Bit area to which the NLRI
disjoint parts, each running an independent IGP domain. belongs. Area Identifier allows the different NLRIs of the same
router to be discriminated.
IGP domain 1 IGP domain 2 IGP Router ID: opaque value. This is a mandatory TLV. For an IS-IS
AS 1 AS 1 non-Pseudonode, this contains 6 octet ISO node-ID (ISO system-ID).
+---+ +---+ For an IS-IS Pseudonode corresponding to a LAN, this contains 6
| | | | octet ISO node-ID of the "Designated Intermediate System" (DIS)
+---+ +---+ followed by one octet nonzero PSN identifier (7 octet in total).
\ / For an OSPFv2 or OSPFv3 non-"Pseudonode", this contains 4 octet
+---------+ Router-ID. For an OSPFv2 "Pseudonode" representing a LAN, this
| | contains 4 octet Router-ID of the designated router (DR) followed
+---------+ by 4 octet IPv4 address of the DR's interface to the LAN (8 octet
Transit AS in total). Similarly, for an OSPFv3 "Pseudonode", this contains 4
octet Router-ID of the DR followed by 4 octet interface identifier
of the DR's interface to the LAN (8 octet in total). The TLV size
in combination with protocol identifier enables the decoder to
determine the type of the node.
Figure 18: Stub-ASs or non-contiguous AS There can be at most one instance of each sub-TLV type present in
any Node Descriptor. The TLV ordering within a Node descriptor
MUST be kept in order of increasing numeric value of type. This
needs to be done in order to compare NLRIs, even when an
implementation encounters an unknown sub-TLV. Using stable
sorting an implementation can do binary comparison of NLRIs and
hence allow incremental deployment of new key sub-TLVs.
Using ASN to globally identify IGP node may break requirement (B). 3.2.1.5. Multi-Topology ID
(ii) It is possible to run the same IGP domain across multiple AS. The Multi-Topology ID (MT-ID) TLV carries one or more IS-IS or OSPF
Multi-Topology IDs for a link, node or prefix.
+----------------------+ Semantics of the IS-IS MT-ID are defined in RFC5120, Section 7.2
| +------+ +------+ | [RFC5120]. Semantics of the OSPF MT-ID are defined in RFC4915,
| | AS 1 | | AS 2 | | Section 3.7 [RFC4915]. If the value in the MT-ID TLV is derived from
| +------+ +------+ | OSPF, then the upper 9 bits MUST be set to 0. Bits R are reserved,
+----------------------+ SHOULD be set to 0 when originated and ignored on receipt.
IGP domain
Figure 19: IGP Domain The format of the MT-ID TLV is shown in the following figure.
Using ASN to globally identify IGP node will break requirement (A). 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length=2*n |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|R R R R| Multi-Topology ID 1 | .... //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// .... |R R R R| Multi-Topology ID n |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(iii) It is possible to run IGP across member-ASs in a confederation. Figure 12: Multi-Topology ID TLV format
+-------------------------------+ where Type is 263, Length is 2*n and n is the number of MT-IDs
| +--------------------------+ | carried in the TLV.
| | +--------+ +--------+ | |
| | | member | | member | | |
| | | AS 1 | | AS 2 | | |
| | +--------+ +--------+ | |
| +--------------------------+ |
| IGP domain |
+-------------------------------+
Confederation (confed-id 1)
Figure 20: Confederation The MT-ID TLV MAY be present in a Link Descriptor, a Prefix
Descriptor, or in the BGP-LS attribute of a node NLRI. In Link or
Prefix Descriptor, only one MT-ID TLV containing only the MT-ID of
the topology where the link or the prefix belongs is allowed. In the
BGP-LS attribute of a node NLRI, one MT-ID TLV containing the array
of MT-IDs of all topologies where the node belongs can be present.
Using a Confederation/MemberAS identifier to globally identify IGP 3.2.2. Link Descriptors
node will break requirement (A).
(iv) It is possible to run more than one IGP domain within an AS by The 'Link Descriptor' field is a set of Type/Length/Value (TLV)
setting up "transit BGP speakers". triplets. The format of each TLV is shown in Section 3.1. The 'Link
descriptor' TLVs uniquely identify a link among multiple parallel
links between a pair of anchor routers. A link described by the Link
descriptor TLVs actually is a "half-link", a unidirectional
representation of a logical link. In order to fully describe a
single logical link two originating routers advertise a half-link
each, i.e. two link NLRIs are advertised for a given point-to-point
link.
+---------------------------------+ The format and semantics of the 'value' fields in most 'Link
| +----------+ +----------+ | Descriptor' TLVs correspond to the format and semantics of value
| | IGP | +---+ | IGP | | fields in IS-IS Extended IS Reachability sub-TLVs, defined in
| | domain 1 +-+ +-+ domain 2 | | [RFC5305], [RFC5307] and [RFC6119]. Although the encodings for 'Link
| +----------+ +---+ +----------+ | Descriptor' TLVs were originally defined for IS-IS, the TLVs can
| ^ | carry data sourced either by IS-IS or OSPF.
| | |
| Transit BGP node |
+---------------------------------+
AS 1
Figure 21: Transit BGP Node The following TLVs are valid as Link Descriptors in the Link NLRI:
Using ASN to globally identify IGP node may break requirement (A). +-----------+---------------------+---------------+-----------------+
| TLV Code | Description | IS-IS | Value defined |
| Point | | TLV/Sub-TLV | in: |
+-----------+---------------------+---------------+-----------------+
| 258 | Link Local/Remote | 22/4 | [RFC5307]/1.1 |
| | Identifiers | | |
| 259 | IPv4 interface | 22/6 | [RFC5305]/3.2 |
| | address | | |
| 260 | IPv4 neighbor | 22/8 | [RFC5305]/3.3 |
| | address | | |
| 261 | IPv6 interface | 22/12 | [RFC6119]/4.2 |
| | address | | |
| 262 | IPv6 neighbor | 22/13 | [RFC6119]/4.3 |
| | address | | |
| 263 | Multi-Topology | --- | Section 3.2.1.5 |
| | Identifier | | |
+-----------+---------------------+---------------+-----------------+
In summary, there is no strict relation between BGP AS division and Table 3: Link Descriptor TLVs
IGP domains. Therefore, the following mechanism is proposed to
address the requirements. We assume that a BGP-LS speaker is
collocated with one and only one IGP node. The BGP-LS speaker
originates BGP-LS NLRIs that correspond to the objects in the LSDB of
that IGP node.
We embed a "string" (identifier) in the node descriptor to globally 3.2.3. Prefix Descriptors
identify the node. The question is how we construct such a string,
and what should be the scope of such a string so that the
construction of the string can be simple. Let the set of IGP nodes
within which LSA/LSP flooding is limited to be the "flooding set".
Consider a given "flooding set". We have the following three
possibilities:
Case a) There is no BGP LS speaker running on any node in the The 'Prefix Descriptor' field is a set of Type/Length/Value (TLV)
flooding set. triplets. 'Prefix Descriptor' TLVs uniquely identify an IPv4 or IPv6
Prefix originated by a Node. The following TLVs are valid as Prefix
Descriptors in the IPv4/IPv6 Prefix NLRI:
Case b) There is one BGP LS speaker running on one node in the +--------------+-----------------------+----------+-----------------+
flooding set. | TLV Code | Description | Length | Value defined |
| Point | | | in: |
+--------------+-----------------------+----------+-----------------+
| 263 | Multi-Topology | variable | Section 3.2.1.5 |
| | Identifier | | |
| 264 | OSPF Route Type | 1 | Section 3.2.3.1 |
| 265 | IP Reachability | variable | Section 3.2.3.2 |
| | Information | | |
+--------------+-----------------------+----------+-----------------+
Case c) There is more than one BGP LS speakers running on the nodes Table 4: Prefix Descriptor TLVs
in the flooding set.
For Case a), the nodes in that flooding set do not appear in BGP LS 3.2.3.1. OSPF Route Type
database. So we can ignore that case for this discussion. To
satisfy requirement (B), the string we use in different IGP domains
must be different. One possible approach is as follows:
Approach 1) The user configures a unique "string" on all BGP LS OSPF Route Type is an optional TLV that MAY be present in Prefix
speakers within one IGP domain. NLRIs. It is used to identify the OSPF route-type of the prefix. It
is used when an OSPF prefix is advertised in the OSPF domain with
multiple different route-types. The Route Type TLV allows to
discriminate these advertisements. The format of the OSPF Route Type
TLV is shown in the following figure.
Now we make an observation that simplifies the task: it is sufficient 0 1 2 3
to have a unique "string" per flooding set. 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Route Type |
+-+-+-+-+-+-+-+-+
When we have a unique string per flooding set, then two nodes in Figure 13: OSPF Route Type TLV Format
different IGP domains, which by definition belong to different
flooding sets, would have different "strings". So requirement B) is
satisfied. On the other hand, a given node appears only in the LSDB
of the nodes in the same flooding set. So a given node will always
have only one "string" and we satisfy requirement A). Given this, we
have:
Approach 2) Each BGP LS speaker uses the <Autonomous System Number, where the Type and Length fields of the TLV are defined in Table 4.
BGP Identifier> as the string. The OSPF Route Type field values are defined in the OSPF protocol,
and can be one of the following:
The combination of <Autonomous System, BGP Identifier> is globally Intra-Area (0x1)
unique, as per [RFC6286].
For Case b), which is the simplest BGP-LS deployment scenario, this Inter-Area (0x2)
approach requires no additional configuration from the user.
For Case c), however, if each BGP-LS speaker in the given flooding External 1 (0x3)
set attaches its own <Autonomous System, BGP Identifier>, then we
will violate requirement A). So that case, the user needs to choose
one of the BGP-LS speakers in the flooding set as the "chosen
speaker" and configure the rest of the BGP-LS speakers in that
flooding set to use the <Autonomous System, BGP Identifier>
combination of the "chosen speaker".
When an IGP node belongs to two or more flooding sets, it views External 2 (0x4)
itself as a collocation of one node per flooding set and accordingly
encodes the NLRIs. Consider the following example:
Level-1 level-1-2 level-1 NSSA 1 (0x5)
N1 N0 N2
+---+ link1 +---+ link 2 +---+
| +-------+ +---------+ |
+---+ +---+ +---+
|<- Level 1 ->| |<- level 2 ->|
L11 L12
"str1" "str2"
Figure 22: IGP Node in multiple flooding sets NSSA 2 (0x6)
The node N0 is a level 1-2 node. Link1 belongs to level 1 area L11, 3.2.3.2. IP Reachability Information
which has string "str1". Link2 belongs to level 1 area L12 which has
string "str2". N0 has both link1 and link2 in its LSDB. If BGP LS
speaker is running on N0, then N0 views itself as a collocation of
two nodes: N0(L11) and N0(L12) and originate <str1, N1, N0> and
<str2, N0, N2>.
To sum up, the mechanism works as follows: The IP Reachability Information is a mandatory TLV that contains one
IP address prefix (IPv4 or IPv6) originally advertised in the IGP
topology. Its purpose is to glue a particular BGP service NLRI vi
virtue of its BGP next-hop to a given Node in the LSDB. A router
SHOULD advertise an IP Prefix NLRI for each of its BGP Next-hops.
The format of the IP Reachability Information TLV is shown in the
following figure:
1. We use <Autonomous System, BGP Identifier> as the 0 1 2 3
disambiguating string. 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Prefix Length | IP Prefix (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2. By default, a BGP-LS speaker uses its own ASN, BGP identifier Figure 14: IP Reachability Information TLV Format
(router-id) for these fields for the NLRIs it originates.
3. Operator has the ability to configure other <ASN, BGP ID> per The Type and Length fields of the TLV are defined in Table 4. The
flooding set the IGP node underneath belongs to. In that case, following two fields determine the address-family reachability
the node descriptor(s) for a given NLRI uses the string information. The 'Prefix Length' field contains the length of the
corresponding to the flooding set where the node belongs. prefix in bits. The 'IP Prefix' field contains the most significant
octets of the prefix; i.e., 1 octet for prefix length 1 up to 8, 2
octets for prefix length 9 to 16, 3 octets for prefix length 17 up to
24 and 4 octets for prefix length 25 up to 32, etc.
The operator needs to provide the configuration if there are multiple 3.3. The LINK_STATE Attribute
BGP-LS speakers running in the same flooding set.
3.2.2.5. Router-ID Anchoring Example: ISO Pseudonode This is an optional, non-transitive BGP attribute that is used to
carry link, node and prefix parameters and attributes. It is defined
as a set of Type/Length/Value (TLV) triplets, described in the
following section. This attribute SHOULD only be included with Link
State NLRIs. This attribute MUST be ignored for all other address-
families.
IS-IS Pseudonodes are a good example for the variable Router-ID 3.3.1. Node Attribute TLVs
anchoring. Consider Figure 23. This represents a Broadcast LAN
between a pair of routers. The "real" (=non pseudonode) routers have
both an IPv4 Router-ID and IS-IS Node-ID. The pseudonode does not
have an IPv4 Router-ID. Two unidirectional links (Node1, Pseudonode
1) and (Pseudonode 1, Node 2) are being generated.
The NRLI for (Node1, Pseudonode1) encodes local IPv4 router-ID, local Node attribute TLVs are the TLVs that may be encoded in the BGP-LS
ISO node-ID and remote ISO node-id) attribute with a node NLRI. The following node attribute TLVs are
defined:
The NLRI for (Pseudonode1, Node2) encodes a local ISO node-ID and +--------------+-----------------------+----------+-----------------+
remote ISO node-id. | TLV Code | Description | Length | Value defined |
| Point | | | in: |
+--------------+-----------------------+----------+-----------------+
| 263 | Multi-Topology | variable | Section 3.2.1.5 |
| | Identifier | | |
| 1024 | Node Flag Bits | 1 | Section 3.3.1.1 |
| 1025 | Opaque Node | variable | Section 3.3.1.5 |
| | Properties | | |
| 1026 | Node Name | variable | Section 3.3.1.3 |
| 1027 | IS-IS Area Identifier | variable | Section 3.3.1.2 |
| 1028 | IPv4 Router-ID of | 4 | [RFC5305]/4.3 |
| | Local Node | | |
| 1029 | IPv6 Router-ID of | 16 | [RFC6119]/4.1 |
| | Local Node | | |
+--------------+-----------------------+----------+-----------------+
+-----------------+ +-----------------+ +-----------------+ Table 5: Node Attribute TLVs
| Node1 | | Pseudonode 1 | | Node2 |
|1920.0000.2001.00|--->|1920.0000.2001.02|--->|1920.0000.2002.00|
| 192.0.2.1 | | | | 192.0.2.2 |
+-----------------+ +-----------------+ +-----------------+
Figure 23: IS-IS Pseudonodes 3.3.1.1. Node Flag Bits TLV
3.2.2.6. Router-ID Anchoring Example: OSPFv2 to IS-IS Migration The Node Flag Bits TLV carries a bit mask describing node attributes.
The value is a variable length bit array of flags, where each bit
represents a node capability.
Migrating gracefully from one IGP to another requires congruent 0 1 2 3
operation of both routing protocols during the migration period. The 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
target protocol (IS-IS) supports more router-ID spaces than the +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
source (OSPFv2) protocol. When advertising a point-to-point link | Type | Length |
between an OSPFv2-only router and an OSPFv2 and IS-IS enabled router +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
the following link information may be generated. Note that the IS-IS |O|T|E|A| Reserved|
router also supports the IPv6 traffic engineering extensions RFC 6119 +-+-+-+-+-+-+-+-+-+
[RFC6119] for IS-IS. Figure 15: Node Flag Bits TLV format
The NRLI encodes local IPv4 router-id, remote IPv4 router-id, remote The bits are defined as follows:
ISO node-id and remote IPv6 node-id.
3.2.3. Link Descriptors +----------+-------------------------+-----------+
| Bit | Description | Reference |
+----------+-------------------------+-----------+
| 'O' | Overload Bit | [RFC1195] |
| 'T' | Attached Bit | [RFC1195] |
| 'E' | External Bit | [RFC2328] |
| 'A' | ABR Bit | [RFC2328] |
| Reserved | Reserved for future use | |
+----------+-------------------------+-----------+
The 'Link Descriptor' field is a set of Type/Length/Value (TLV) Table 6: Node Flag Bits Definitions
triplets. The format of each TLV is shown in Section 3.1. The 'Link
descriptor' TLVs uniquely identify a link between a pair of anchor
Routers. A link described by the Link descriptor TLVs actually is a
"half-link", a unidirectional representation of a logical link. In
order to fully describe a single logical link two originating routers
need to advertise a half-link each, i.e. two link NLRIs will be
advertised.
The format and semantics of the 'value' fields in most 'Link 3.3.1.2. IS-IS Area Identifier TLV
Descriptor' TLVs correspond to the format and semantics of value
fields in IS-IS Extended IS Reachability sub-TLVs, defined in
[RFC5305], [RFC5307] and [RFC6119]. Although the encodings for 'Link
Descriptor' TLVs were originally defined for IS-IS, the TLVs can
carry data sourced either by IS-IS or OSPF.
The following link descriptor TLVs are valid in the Link NLRI: An IS-IS node can be part of one or more IS-IS areas. Each of these
area addresses is carried in the IS-IS Area Identifier TLV. If more
than one Area Addresses are present, multiple TLVs are used to encode
them. The IS-IS Area Identifier TLV may be present in the LINK_STATE
attribute only with the Link State Node NLRI.
+------------+--------------------+---------------+-----------------+ 0 1 2 3
| TLV/SubTLV | Description | IS-IS | Value defined | 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
| | | TLV/Sub-TLV | in: | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+------------+--------------------+---------------+-----------------+ | Type | Length |
| 264 | Link Local/Remote | 22/4 | [RFC5307]/1.1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | Identifiers | | | // Area Identifier (variable) //
| 265 | IPv4 interface | 22/6 | [RFC5305]/3.2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | address | | |
| 266 | IPv4 neighbor | 22/8 | [RFC5305]/3.3 |
| | address | | |
| 267 | IPv6 interface | 22/12 | [RFC6119]/4.2 |
| | address | | |
| 268 | IPv6 neighbor | 22/13 | [RFC6119]/4.3 |
| | address | | |
| 256/5 | Multi Topology ID | --- | Section 3.2.1.5 |
+------------+--------------------+---------------+-----------------+
Table 2: Link Descriptor TLVs Figure 16: IS-IS Area Identifier TLV Format
3.2.4. Prefix Descriptors 3.3.1.3. Node Name TLV
The 'Prefix descriptor' TLVs uniquely identify a Prefix (IPv4 or The Node Name TLV is optional. Its structure and encoding has been
IPv6) originated by a Node. borrowed from [RFC5301]. The value field identifies the symbolic
name of the router node. This symbolic name can be the FQDN for the
router, it can be a subset of the FQDN, or it can be any string
operators want to use for the router. The use of FQDN or a subset of
it is strongly recommended.
The following Prefix descriptor TLVs are valid in the IPv4/IPv6 The Value field is encoded in 7-bit ASCII. If a user-interface for
Prefix NLRI: configuring or displaying this field permits Unicode characters, that
user-interface is responsible for applying the ToASCII and/or
ToUnicode algorithm as described in [RFC3490] to achieve the correct
format for transmission or display.
+------------+-----------------+-----------------+------------------+ Altough [RFC5301] is a IS-IS specific extension, usage of the Node
| TLV/SubTLV | Description | IS-IS | Value defined | Name TLV is possible for all protocols. How a router derives and
| | | TLV/Sub-TLV | in: | injects node names for e.g. OSPF nodes, is outside of the scope of
+------------+-----------------+-----------------+------------------+ this document.
| 256/5 | Multi Topology | --- | Section 3.2.1.5 |
| | ID | | |
+------------+-----------------+-----------------+------------------+
Table 3: Prefix Descriptor TLVs 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Node Name (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.2.4.1. The Prefix NLRI Figure 17: Node Name format
The Prefix NLRI is a variable length field that contains one or more 3.3.1.4. Local IPv4/IPv6 Router-ID
IP address prefixes (IPv4 or IPv6) originally advertised in the IGP
topology. The NLRI Type determines the address-family. Reachability
information is encoded as one or more 2-tuples of the form <length,
prefix>, whose fields are described below:
+---------------------------+ The local IPv4/IPv6 Router-ID TLVs are used to describe auxiliary
| Length (1 octet) | Router-IDs that the IGP might be using, e.g., for TE and migration
+---------------------------+ purposes like correlating a Node-ID between different protocols. If
| Prefix (variable) | there is more than one auxiliary Router-ID of a given type, then each
+---------------------------+ one is encoded in its own TLV.
Figure 24: Prefix NLRI format 3.3.1.5. Opaque Node Attribute TLV
The 'Length' field contains the length of the prefix in bits. Only The Opaque Node attribute TLV is an envelope that transparently
the most significant octets of the prefix are encoded. I.e. 1 octet carries optional node attribute TLVs advertised by a router. An
for prefix length 1 up to 8, 2 octets for prefix length 9 to 16, 3 originating router shall use this TLV for encoding information
octets for prefix length 17 up to 24 and 4 octets for prefix length specific to the protocol advertised in the NLRI header Protocol-ID
25 up to 32, etc. field or new protocol extensions to the protocol as advertised in the
NLRI header Protocol-ID field for which there is no protocol neutral
representation in the BGP link-state NLRI. A router for example
could use this extension in order to advertise the native protocols
node attribute TLVs, such as the OSPF Router Informational
Capabilities TLV defined in [RFC4970], or the IGP TE Node Capability
Descriptor TLV described in [RFC5073].
3.3. The LINK_STATE Attribute 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Opaque node attributes (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This is an optional, non-transitive BGP attribute that is used to Figure 18: Opaque Node attribute format
carry link, node and prefix parameters and attributes. It is defined
as a set of Type/Length/Value (TLV) triplets, described in the
following section. This attribute SHOULD only be included with Link
State NLRIs. This attribute MUST be ignored for all other NLRIs.
3.3.1. Link Attribute TLVs 3.3.2. Link Attribute TLVs
Each 'Link Attribute' is a Type/Length/Value (TLV) triplet formatted Link attribute TLVs are TLVs that may be encoded in the BGP-LS
as defined in Section 3.1. The format and semantics of the 'value' attribute with a link NLRI. Each 'Link Attribute' is a Type/Length/
fields in some 'Link Attribute' TLVs correspond to the format and Value (TLV) triplet formatted as defined in Section 3.1. The format
semantics of value fields in IS-IS Extended IS Reachability sub-TLVs, and semantics of the 'value' fields in some 'Link Attribute' TLVs
defined in [RFC5305] and [RFC5307]. Other 'Link Attribute' TLVs are correspond to the format and semantics of value fields in IS-IS
defined in this document. Although the encodings for 'Link Extended IS Reachability sub-TLVs, defined in [RFC5305] and
Attribute' TLVs were originally defined for IS-IS, the TLVs can carry [RFC5307]. Other 'Link Attribute' TLVs are defined in this document.
data sourced either by IS-IS or OSPF. Although the encodings for 'Link Attribute' TLVs were originally
defined for IS-IS, the TLVs can carry data sourced either by IS-IS or
OSPF.
The following 'Link Attribute' TLVs are are valid in the LINK_STATE The following 'Link Attribute' TLVs are are valid in the LINK_STATE
attribute: attribute:
+------------+---------------------+--------------+-----------------+ +------------+---------------------+--------------+-----------------+
| TLV/SubTLV | Description | IS-IS | Defined in: | | TLV Code | Description | IS-IS | Defined in: |
| | | TLV/Sub-TLV | | | Point | | TLV/Sub-TLV | |
+------------+---------------------+--------------+-----------------+ +------------+---------------------+--------------+-----------------+
| 256/3 | Area Identifier | --- | Section 3.2.1.3 | | 1028 | IPv4 Router-ID of | 134/--- | [RFC5305]/4.3 |
| 269 | Administrative | 22/3 | [RFC5305]/3.1 | | | Local Node | | |
| 1029 | IPv6 Router-ID of | 140/--- | [RFC6119]/4.1 |
| | Local Node | | |
| 1030 | IPv4 Router-ID of | 134/--- | [RFC5305]/4.3 |
| | Remote Node | | |
| 1031 | IPv6 Router-ID of | 140/--- | [RFC6119]/4.1 |
| | Remote Node | | |
| 1088 | Administrative | 22/3 | [RFC5305]/3.1 |
| | group (color) | | | | | group (color) | | |
| 270 | Maximum link | 22/9 | [RFC5305]/3.3 | | 1089 | Maximum link | 22/9 | [RFC5305]/3.3 |
| | bandwidth | | | | | bandwidth | | |
| 271 | Max. reservable | 22/10 | [RFC5305]/3.5 | | 1090 | Max. reservable | 22/10 | [RFC5305]/3.5 |
| | link bandwidth | | | | | link bandwidth | | |
| 272 | Unreserved | 22/11 | [RFC5305]/3.6 | | 1091 | Unreserved | 22/11 | [RFC5305]/3.6 |
| | bandwidth | | | | | bandwidth | | |
| 273 | TE Default Metric | 22/18 | [RFC5305]/3.7 | | 1092 | TE Default Metric | 22/18 | [RFC5305]/3.7 |
| 274 | Link Protection | 22/20 | [RFC5307]/1.2 | | 1093 | Link Protection | 22/20 | [RFC5307]/1.2 |
| | Type | | | | | Type | | |
| 275 | MPLS Protocol Mask | --- | Section 3.3.1.1 | | 1094 | MPLS Protocol Mask | --- | Section 3.3.2.2 |
| 276 | Metric | --- | Section 3.3.1.2 | | 1095 | Metric | --- | Section 3.3.2.3 |
| 277 | Shared Risk Link | --- | Section 3.3.1.3 | | 1096 | Shared Risk Link | --- | Section 3.3.2.4 |
| | Group | | | | | Group | | |
| 278 | OSPF specific link | --- | Section 3.3.1.4 | | 1097 | Opaque link | --- | Section 3.3.2.5 |
| | attribute | | | | | attribute | | |
| 279 | IS-IS Specific Link | --- | Section 3.3.1.5 | | 1098 | Link Name attribute | --- | Section 3.3.2.6 |
| | Attribute | | |
+------------+---------------------+--------------+-----------------+ +------------+---------------------+--------------+-----------------+
Table 4: Link Attribute TLVs Table 7: Link Attribute TLVs
3.3.1.1. MPLS Protocol Mask TLV 3.3.2.1. IPv4/IPv6 Router-ID
The MPLS Protocol TLV (Type 275) carries a bit mask describing which The local/remote IPv4/IPv6 Router-ID TLVs are used to describe
MPLS signaling protocols are enabled. The length of this TLV is 1. auxiliary Router-IDs that the IGP might be using, e.g., for TE
The value is a bit array of 8 flags, where each bit represents an purposes. All auxiliary Router-IDs of both the local and the remote
MPLS Protocol capability. node MUST be included in the link attribute of each link NLRI. If
there are more than one auxiliary Router-ID of a given type, then
multiple TLVs are used to encode them.
3.3.2.2. MPLS Protocol Mask TLV
The MPLS Protocol TLV carries a bit mask describing which MPLS
signaling protocols are enabled. The length of this TLV is 1. The
value is a bit array of 8 flags, where each bit represents an MPLS
Protocol capability.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L R | |L|R| Reserved |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Figure 25: MPLS Protocol TLV Figure 19: MPLS Protocol TLV
The following bits are defined: The following bits are defined:
+-----+---------------------------------------------+-----------+ +------------+------------------------------------------+-----------+
| Bit | Description | Reference | | Bit | Description | Reference |
+-----+---------------------------------------------+-----------+ +------------+------------------------------------------+-----------+
| 0 | Label Distribution Protocol (LDP) | [RFC5036] | | 'L' | Label Distribution Protocol (LDP) | [RFC5036] |
| 1 | Extension to RSVP for LSP Tunnels (RSVP-TE) | [RFC3209] | | 'R' | Extension to RSVP for LSP Tunnels | [RFC3209] |
| 2-7 | Reserved for future use | | | | (RSVP-TE) | |
+-----+---------------------------------------------+-----------+ | 'Reserved' | Reserved for future use | |
+------------+------------------------------------------+-----------+
Table 5: MPLS Protocol Mask TLV Codes Table 8: MPLS Protocol Mask TLV Codes
3.3.1.2. Metric TLV 3.3.2.3. Metric TLV
The IGP Metric TLV (Type 276) carries the metric for this link. The The IGP Metric TLV carries the metric for this link. The length of
length of this TLV is 3. If the length of the metric from which the this TLV is variable, depending on the metric width of the underlying
IGP Metric value is derived is less than 3 (e.g. for OSPF link protocol. IS-IS small metrics have a length of 1 octet (the two most
metrics or non-wide IS-IS metric), then the upper bits of the TLV are significant bits are ignored). OSPF metrics have a length of two
set to 0. octects. IS-IS wide-metrics have a length of three octets.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IGP Link Metric | // IGP Link Metric (variable length) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 26: Metric TLV format Figure 20: Metric TLV format
3.3.1.3. Shared Risk Link Group TLV 3.3.2.4. Shared Risk Link Group TLV
The Shared Risk Link Group (SRLG) TLV (Type 277) carries the Shared The Shared Risk Link Group (SRLG) TLV carries the Shared Risk Link
Risk Link Group information (see Section 2.3, "Shared Risk Link Group Group information (see Section 2.3, "Shared Risk Link Group
Information", of [RFC4202]). It contains a data structure consisting Information", of [RFC4202]). It contains a data structure consisting
of a (variable) list of SRLG values, where each element in the list of a (variable) list of SRLG values, where each element in the list
has 4 octets, as shown in Figure 27. The length of this TLV is 4 * has 4 octets, as shown in Figure 21. The length of this TLV is 4 *
(number of SRLG values). (number of SRLG values).
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Shared Risk Link Group Value | | Shared Risk Link Group Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ............ | // ............ //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Shared Risk Link Group Value | | Shared Risk Link Group Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 27: Shared Risk Link Group TLV format Figure 21: Shared Risk Link Group TLV format
Note that there is no SRLG TLV in OSPF-TE. In IS-IS the SRLG Note that there is no SRLG TLV in OSPF-TE. In IS-IS the SRLG
information is carried in two different TLVs: the IPv4 (SRLG) TLV information is carried in two different TLVs: the IPv4 (SRLG) TLV
(Type 138) defined in [RFC5307], and the IPv6 SRLG TLV (Type 139) (Type 138) defined in [RFC5307], and the IPv6 SRLG TLV (Type 139)
defined in [RFC6119]. Since the Link State NLRI uses variable defined in [RFC6119]. In Link State NLRI both IPv4 and IPv6 SRLG
Router-ID anchoring, both IPv4 and IPv6 SRLG information can be information are carried in a single TLV.
carried in a single TLV.
3.3.1.4. OSPF Specific Link Attribute TLV
The OSPF specific link attribute TLV (Type 278) is an envelope that
transparently carries optional link properties TLVs advertised by an
OSPF router. The value field contains one or more optional OSPF link
attribute TLVs. An originating router shall use this TLV for
encoding information specific to the OSPF protocol or new OSPF
extensions for which there is no protocol neutral representation in
the BGP link-state NLRI.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| OSPF specific link attributes (variable) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 28: OSPF specific link attribute format
3.3.1.5. IS-IS specific link attribute TLV
The IS-IS specific link attribute TLV (Type 279) is an envelope that
transparently carries optional link properties TLVs advertised by an
IS-IS router. The value field contains one or more optional IS-IS
link attribute TLVs. An originating router shall use this TLV for
encoding information specific to the IS-IS protocol or new IS-IS
extensions for which there is no protocol neutral representation in
the BGP link-state NLRI.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| IS-IS specific link attributes (variable) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 29: IS-IS specific link attribute format
3.3.1.6. IS-IS Area Address attribute TLV
The area address is carried in the Area Identifier SubTLV of the
Identifier TLV and consists of the Area Address which is assigned to
the link. If more than one Area Addresses are present, only the
lower address is encoded. Note that the Area Identifier SubTLV may
appear in all NLRI types (Link, Node and Prefix) and is defined in
Section 3.2.1.3.
3.3.2. Node Attribute TLVs
The following node attribute TLVs are defined:
+------------+--------------------------------------+----------+
| TLV/SubTLV | Description | Length |
+------------+--------------------------------------+----------+
| 256/5 | Multi Topology | 2 |
| 280 | Node Flag Bits | 1 |
| 281 | OSPF Specific Node Properties | variable |
| 282 | IS-IS Specific Node Properties | variable |
| 256 | IS-IS Area Address/Domain Identifier | variable |
+------------+--------------------------------------+----------+
Table 6: Node Attribute TLVs
3.3.2.1. Node Multi Topology ID
The Node Multi Topology ID is carried in the Multi Topolofy ID SubTLV
(type 5) of Identifier ID TLV TLV (Type 256) and carries the Multi
Topology ID and topology specific flags for this node. The format
and semantics of the 'value' field in the Multi Topology TLV is
defined in Section 3.2.1.5. If the value in the Multi Topology TLV
is derived from OSPF, then the upper 9 bits of the Multi Topology ID
and the 'O' and 'A' bits are set to 0.
3.3.2.2. Node Flag Bits TLV 3.3.2.5. Opaque Link Attribute TLV
The Node Flag Bits TLV (Type 280) carries a bit mask describing node The Opaque link attribute TLV is an envelope that transparently
attributes. The value is a variable length bit array of flags, where carries optional link atrribute TLVs advertised by a router. An
each bit represents a node capability. originating router shall use this TLV for encoding information
specific to the protocol advertised in the NLRI header Protocol-ID
field or new protocol extensions to the protocol as advertised in the
NLRI header Protocol-ID field for which there is no protocol neutral
representation in the BGP link-state NLRI.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags (variable) | // Opaque link attributes (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 30: Node Flag Bits TLV format Figure 22: Opaque link attribute format
The bits are defined as follows:
+-----+--------------+-----------+
| Bit | Description | Reference |
+-----+--------------+-----------+
| 0 | Overload Bit | [RFC1195] |
| 1 | Attached Bit | [RFC1195] |
| 2 | External Bit | [RFC2328] |
| 3 | ABR Bit | [RFC2328] |
+-----+--------------+-----------+
Table 7: Node Flag Bits Definitions
3.3.2.3. OSPF Specific Node Properties TLV
The OSPF Specific Node Properties TLV (Type 281) is an envelope that
transparently carries optional node properties TLVs advertised by an
OSPF router. The value field contains one or more optional OSPF node
property TLVs, such as the OSPF Router Informational Capabilities TLV
defined in [RFC4970], or the OSPF TE Node Capability Descriptor TLV
described in [RFC5073]. An originating router shall use this TLV for
encoding information specific to the OSPF protocol or new OSPF
extensions for which there is no protocol neutral representation in
the BGP link-state NLRI.
0 1 2 3 3.3.2.6. Link Name TLV
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| OSPF specific node properties (variable) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 31: OSPF specific Node property format The Link Name TLV is optional. The value field identifies the
symbolic name of the router link. This symbolic name can be the FQDN
for the link, it can be a subset of the FQDN, or it can be any string
operators want to use for the link. The use of FQDN or a subset of
it is strongly recommended.
3.3.2.4. IS-IS Specific Node Properties TLV The Value field is encoded in 7-bit ASCII. If a user-interface for
configuring or displaying this field permits Unicode characters, that
user-interface is responsible for applying the ToASCII and/or
ToUnicode algorithm as described in [RFC3490] to achieve the correct
format for transmission or display.
The IS-IS Router Specific Node Properties TLV (Type 282) is an How a router derives and injects link names is outside of the scope
envelope that transparently carries optional node specific TLVs of this document.
advertised by an IS-IS router. The value field contains one or more
optional IS-IS node property TLVs, such as the IS-IS TE Node
Capability Descriptor TLV described in [RFC5073]. An originating
router shall use this TLV for encoding information specific to the
IS-IS protocol or new IS-IS extensions for which there is no protocol
neutral representation in the BGP link-state NLRI.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | // Link Name (variable) //
| IS-IS specific node properties (variable) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 32: IS-IS specific Node property format Figure 23: Link Name format
3.3.2.5. ISIS Area Address TLV
The area address is carried in the Area Identifier SubTLV of the
Identifier TLV and consists of the Area Address which is assigned to
the node. If more than one Area Addresses are present, only the
lower address is encoded. Note that the Area Identifier SubTLV may
appear in all NLRI types (Link, Node and Prefix) and is defined in
Section 3.2.1.3.
3.3.3. Prefix Attributes TLVs 3.3.3. Prefix Attribute TLVs
Prefixes are learned from the IGP topology (ISIS or OSPF) with a set Prefixes are learned from the IGP topology (IS-IS or OSPF) with a set
of IGP attributes (such as metric, route tags, etc.) that MUST be of IGP attributes (such as metric, route tags, etc.) that MUST be
reflected into the LINK_STATE attribute. This section describes the reflected into the LINK_STATE attribute. This section describes the
different attributes related to the IPv4/IPv6 prefixes. Prefix different attributes related to the IPv4/IPv6 prefixes. Prefix
Attributes TLVs SHOULD be used when advertising NLRI types 3 and 4 Attributes TLVs SHOULD be used when advertising NLRI types 3 and 4
only. The following attributes TLVs are defined: only. The following attributes TLVs are defined:
+-------------------------+-------------+-----------+-----------+ +---------------+----------------------+----------+-----------------+
| TLV/SubTLV | Description | Length | Reference | | TLV Code | Description | Length | Reference |
+-------------------------+-------------+-----------+-----------+ | Point | | | |
| 283 | IGP Flags | 4 | 284 | +---------------+----------------------+----------+-----------------+
| Route Tag | 4*n | [RFC5130] | 285 | | 1152 | IGP Flags | 1 | Section 3.3.3.1 |
| Extended Tag | 8*n | [RFC5130] | 286 | | 1153 | Route Tag | 4*n | Section 3.3.3.2 |
| Prefix Metric | 4 | [RFC5305] | 287 | | 1154 | Extended Tag | 8*n | Section 3.3.3.3 |
| OSPF Forwarding Address | 4 | [RFC2328] | | | 1155 | Prefix Metric | 4 | Section 3.3.3.4 |
+-------------------------+-------------+-----------+-----------+ | 1156 | OSPF Forwarding | 4 | Section 3.3.3.5 |
| | Address | | |
| 1157 | Opaque Prefix | variable | Section 3.3.3.6 |
| | Attribute | | |
+---------------+----------------------+----------+-----------------+
Table 8: Prefix Attribute TLVs Table 9: Prefix Attribute TLVs
3.3.3.1. IGP Flags TLV 3.3.3.1. IGP Flags TLV
IGP Flags TLV contains ISIS and OSPF flags and bits originally IGP Flags TLV contains IS-IS and OSPF flags and bits originally
assigned to the prefix. The IGP Flags TLV is encoded as follows: assigned to the prefix. The IGP Flags TLV is encoded as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IGP Flags (variable) | |D| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Figure 33: IGP Flag TLV format
where:
Type is 283
Length is variable Figure 24: IGP Flag TLV format
The following bits are defined according to the table here below: The value field contains bits defined according to the table below:
+------+------------------+-----------+ +----------+--------------------------+-----------+
| Bit | Description | Reference | | Bit | Description | Reference |
+------+------------------+-----------+ +----------+--------------------------+-----------+
| 0 | ISIS Up/Down Bit | [RFC5305] | | 'D' | IS-IS Up/Down Bit | [RFC5305] |
| 1-3 | OSPF Route Type | [RFC2328] | | Reserved | Reserved for future use. | |
| 4-15 | RESERVED | | +----------+--------------------------+-----------+
+------+------------------+-----------+
Table 9: IGP Flag Bits Definitions
OSPF Route Type can be either: Intra-Area (0x1), Inter-Area (0x2), Table 10: IGP Flag Bits Definitions
External 1 (0x3), External 2 (0x4), NSSA (0x5) and is encoded in a 3
bits number. For prefixes learned from IS-IS, this field MUST to be
set to 0x0 on transmission.
3.3.3.2. Route Tag 3.3.3.2. Route Tag
Route Tag TLV carries the original IGP TAG (ISIS or OSPF) of the Route Tag TLV carries original IGP TAGs (IS-IS [RFC5130] or OSPF) of
prefix and is encoded as follows: the prefix and is encoded as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Route Tags (one or more) | // Route Tags (one or more) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 34: IGP Route TAG TLV format Figure 25: IGP Route TAG TLV format
where:
Type is 284
Length is a multiple of 4 Length is a multiple of 4.
One or more Route Tags as learned in the IGP topology. The value field contains one or more Route Tags as learned in the IGP
topology.
3.3.3.3. Extended Route Tag 3.3.3.3. Extended Route Tag
Extended Route Tag TLV carries the ISIS Extended Route TAG of the Extended Route Tag TLV carries IS-IS Extended Route TAGs of the
prefix and is encoded as follows: prefix [RFC5130] and is encoded as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Extended Route Tag (one or more) | // Extended Route Tag (one or more) //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 35: Extended IGP Route TAG TLV format Figure 26: Extended IGP Route TAG TLV format
where:
Type is 285
Length is a multiple of 8 Length is a multiple of 8.
Extended Route Tag contains one or more Extended Route Tags as The 'Extended Route Tag' field contains one or more Extended Route
learned in the IGP topology. Tags as learned in the IGP topology.
3.3.3.4. Prefix Metric TLV 3.3.3.4. Prefix Metric TLV
Prefix Metric TLV carries the metric of the prefix as known in the Prefix Metric TLV carries the metric of the prefix as known in the
IGP topology. The attribute is mandatory and can only appear once. IGP topology [RFC5305]. The attribute is mandatory and can only
appear once.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metric | | Metric |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 36: Prefix Metric TLV Format Figure 27: Prefix Metric TLV Format
where:
Type is 286
Length is 4 Length is 4.
3.3.3.5. OSPF Forwarding Address TLV 3.3.3.5. OSPF Forwarding Address TLV
OSPF Forwarding Address TLV carries the OSPF forwarding address as OSPF Forwarding Address TLV [RFC2328] carries the OSPF forwarding
known in the original OSPF advertisement. Forwarding address can be address as known in the original OSPF advertisement. Forwarding
either IPv4 or IPv6. address can be either IPv4 or IPv6.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Forwarding Address (variable) | // Forwarding Address (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 37: OSPF Forwarding Address TLV Format Figure 28: OSPF Forwarding Address TLV Format
where:
Type is 287
Length is 4 for an IPv4 forwarding address an 16 for an IPv6 Length is 4 for an IPv4 forwarding address an 16 for an IPv6
forwarding address forwarding address.
3.3.3.6. Opaque Prefix Attribute TLV
The Opaque Prefix attribute TLV is an envelope that transparently
carries optional prefix attribute TLVs advertised by a router. An
originating router shall use this TLV for encoding information
specific to the protocol advertised in the NLRI header Protocol-ID
field or new protocol extensions to the protocol as advertised in the
NLRI header Protocol-ID field for which there is no protocol neutral
representation in the BGP link-state NLRI.
The format of the TLV is as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Opaque Prefix Attributes (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 29: Opaque Prefix Attribute TLV Format
Type is as specified in Table 9 and Length is variable.
3.4. BGP Next Hop Information 3.4. BGP Next Hop Information
BGP link-state information for both IPv4 and IPv6 networks can be BGP link-state information for both IPv4 and IPv6 networks can be
carried over either an IPv4 BGP session, or an IPv6 BGP session. If carried over either an IPv4 BGP session, or an IPv6 BGP session. If
IPv4 BGP session is used, then the next hop in the MP_REACH_NLRI IPv4 BGP session is used, then the next hop in the MP_REACH_NLRI
SHOULD be an IPv4 address. Similarly, if IPv6 BGP session is used, SHOULD be an IPv4 address. Similarly, if IPv6 BGP session is used,
then the next hop in the MP_REACH_NLRI SHOULD be an IPv6 address. then the next hop in the MP_REACH_NLRI SHOULD be an IPv6 address.
Usually the next hop will be set to the local end-point address of Usually the next hop will be set to the local end-point address of
the BGP session. The next hop address MUST be encoded as described the BGP session. The next hop address MUST be encoded as described
in [RFC4760]. The length field of the next hop address will specify in [RFC4760]. The length field of the next hop address will specify
the next hop address-family. If the next hop length is 4, then the the next hop address-family. If the next hop length is 4, then the
next hop is an IPv4 address; if the next hop length is 16, then it is next hop is an IPv4 address; if the next hop length is 16, then it is
a global IPv6 address and if the next hop length is 32, then there is a global IPv6 address and if the next hop length is 32, then there is
one global IPv6 address followed by a link-local IPv6 address. The one global IPv6 address followed by a link-local IPv6 address. The
link-local IPv6 address should be used as described in [RFC2545]. link-local IPv6 address should be used as described in [RFC2545].
For VPN SAFI, as per custom, an 8 byte route-distinguisher set to all
zero is prepended to the next hop.
The BGP Next Hop attribute is used by each BGP-LS spaker to validate The BGP Next Hop attribute is used by each BGP-LS speaker to validate
the NLRI it receives. However, this specification doesn't mandate the NLRI it receives. However, this specification doesn't mandate
any rule regarding the re-write of the BGP Next Hop attribute. any rule regarding the re-write of the BGP Next Hop attribute.
3.5. Inter-AS Links 3.5. Inter-AS Links
The main source of TE information is the IGP, which is not active on The main source of TE information is the IGP, which is not active on
inter-AS links. In order to inject a non-IGP enabled link into the inter-AS links. In some cases, the IGP may have information of
BGP link-state RIB an implementation must support configuration of inter-AS links ([RFC5392], [RFC5316]). In other cases, for injecting
static links. a non-IGP enabled link into the BGP link-state RIB, an implementation
MUST support configuration of either 'Static' or 'Direct' links.
3.6. Router-ID Anchoring Example: ISO Pseudonode
Encoding of a broadcast LAN in IS-IS provides a good example of how
Router-IDs are encoded. Consider Figure 30. This represents a
Broadcast LAN between a pair of routers. The "real" (=non
pseudonode) routers have both an IPv4 Router-ID and IS-IS Node-ID.
The pseudonode does not have an IPv4 Router-ID. Node1 is the DIS for
the LAN. Two unidirectional links (Node1, Pseudonode 1) and
(Pseudonode1, Node2) are being generated.
The link NRLI of (Node1, Pseudonode1) is encoded as follows: the IGP
Router-ID TLV of the local node descriptor is 6 octets long
containing ISO-ID of Node1, 1920.0000.2001; the IGP Router-ID TLV of
the remote node descriptor is 7 octets long containing the ISO-ID of
Pseudonode1, 1920.0000.2001.02. The BGP-LS attribute of this link
contains one local IPv4 Router-ID TLV (TLV type 1028) containing
192.0.2.1, the IPv4 Router-ID of Node1.
The link NRLI of (Pseudonode1. Node2) is encoded as follows: the IGP
Router-ID TLV of the local node descriptor is 7 octets long
containing the ISO-ID of Pseudonode1, 1920.0000.2001.02; the IGP
Router-ID TLV of the remote node descriptor is 6 octets long
containing ISO-ID of Node2, 1920.0000.2002. The BGP-LS attribute of
this link contains one remote IPv4 Router-ID TLV (TLV type 1030)
containing 192.0.2.2, the IPv4 Router-ID of Node2.
+-----------------+ +-----------------+ +-----------------+
| Node1 | | Pseudonode1 | | Node2 |
|1920.0000.2001.00|--->|1920.0000.2001.02|--->|1920.0000.2002.00|
| 192.0.2.1 | | | | 192.0.2.2 |
+-----------------+ +-----------------+ +-----------------+
Figure 30: IS-IS Pseudonodes
3.7. Router-ID Anchoring Example: OSPFv2 to IS-IS Migration
Graceful migration from one IGP to another requires coordinated
operation of both protocols during the migration period. Such a
coordination requires identifying a given physical link in both IGPs.
The IPv4 Router-ID provides that "glue" which is present in the node
descriptors of the OSPF link NLRI and in the link attribute of the
IS-IS link NLRI.
Consider a point-to-point link between two routers, A and B, that
initially were OSPFv2-only routers and then IS-IS is enabled on them.
Node A has IPv4 Router-ID and ISO-ID; node B has IPv4 Router-ID, IPv6
Router-ID and ISO-ID. Each protocol generates one link NLRI for the
link (A, B), both of which are carried by BGP-LS. The OSPFv2 link
NLRI for the link is encoded with the IPv4 Router-ID of nodes A and B
in the local and remote node descriptors, respectively. The IS-IS
link NLRI for the link is encoded with the ISO-ID of nodes A and B in
the local and remote node descriptors, respectively. In addition,
the BGP-LS attribute of the IS-IS link NLRI contains the the TLV type
1028 containing the IPv4 Router-ID of node A; TLV type 1030
containing the IPv4 Router-ID of node B and TLV type 1031 containing
the IPv6 Router-ID of node B. In this case, by using IPv4 Router-ID,
the link (A, B) can be identified in both IS-IS and OSPF protocol.
4. Link to Path Aggregation 4. Link to Path Aggregation
Distribution of all links available in the global Internet is Distribution of all links available in the global Internet is
certainly possible, however not desirable from a scaling and privacy certainly possible, however not desirable from a scaling and privacy
point of view. Therefore an implementation may support link to path point of view. Therefore an implementation may support link to path
aggregation. Rather than advertising all specific links of a domain, aggregation. Rather than advertising all specific links of a domain,
an ASBR may advertise an "aggregate link" between a non-adjacent pair an ASBR may advertise an "aggregate link" between a non-adjacent pair
of nodes. The "aggregate link" represents the aggregated set of link of nodes. The "aggregate link" represents the aggregated set of link
properties between a pair of non-adjacent nodes. The actual methods properties between a pair of non-adjacent nodes. The actual methods
to compute the path properties (of bandwidth, metric) are outside the to compute the path properties (of bandwidth, metric) are outside the
scope of this document. The decision whether to advertise all scope of this document. The decision whether to advertise all
specific links or aggregated links is an operator's policy choice. specific links or aggregated links is an operator's policy choice.
To highlight the varying levels of exposure, the following deployment To highlight the varying levels of exposure, the following deployment
examples shall be discussed. examples are discussed.
4.1. Example: No Link Aggregation 4.1. Example: No Link Aggregation
Consider Figure 38. Both AS1 and AS2 operators want to protect their Consider Figure 31. Both AS1 and AS2 operators want to protect their
inter-AS {R1,R3}, {R2, R4} links using RSVP-FRR LSPs. If R1 wants to inter-AS {R1,R3}, {R2, R4} links using RSVP-FRR LSPs. If R1 wants to
compute its link-protection LSP to R3 it needs to "see" an alternate compute its link-protection LSP to R3 it needs to "see" an alternate
path to R3. Therefore the AS2 operator exposes its topology. All path to R3. Therefore the AS2 operator exposes its topology. All
BGP TE enabled routers in AS1 "see" the full topology of AS and BGP TE enabled routers in AS1 "see" the full topology of AS and
therefore can compute a backup path. Note that the decision if the therefore can compute a backup path. Note that the decision if the
direct link between {R3, R4} or the {R4, R5, R3) path is used is made direct link between {R3, R4} or the {R4, R5, R3) path is used is made
by the computing router. by the computing router.
AS1 : AS2 AS1 : AS2
: :
R1-------R3 R1-------R3
| : | \ | : | \
| : | R5 | : | R5
| : | / | : | /
R2-------R4 R2-------R4
: :
: :
Figure 38: no-link-aggregation Figure 31: No link aggregation
4.2. Example: ASBR to ASBR Path Aggregation 4.2. Example: ASBR to ASBR Path Aggregation
The brief difference between the "no-link aggregation" example and The brief difference between the "no-link aggregation" example and
this example is that no specific link gets exposed. Consider this example is that no specific link gets exposed. Consider
Figure 39. The only link which gets advertised by AS2 is an Figure 32. The only link which gets advertised by AS2 is an
"aggregate" link between R3 and R4. This is enough to tell AS1 that "aggregate" link between R3 and R4. This is enough to tell AS1 that
there is a backup path. However the actual links being used are there is a backup path. However the actual links being used are
hidden from the topology. hidden from the topology.
AS1 : AS2 AS1 : AS2
: :
R1-------R3 R1-------R3
| : | | : |
| : | | : |
| : | | : |
R2-------R4 R2-------R4
: :
: :
Figure 39: asbr-link-aggregation Figure 32: ASBR link aggregation
4.3. Example: Multi-AS Path Aggregation 4.3. Example: Multi-AS Path Aggregation
Service providers in control of multiple ASes may even decide to not Service providers in control of multiple ASes may even decide to not
expose their internal inter-AS links. Consider Figure 40. AS3 is expose their internal inter-AS links. Consider Figure 33. AS3 is
modeled as a single node which connects to the border routers of the modeled as a single node which connects to the border routers of the
aggregated domain. aggregated domain.
AS1 : AS2 : AS3 AS1 : AS2 : AS3
: : : :
R1-------R3----- R1-------R3-----
| : : \ | : : \
| : : vR0 | : : vR0
| : : / | : : /
R2-------R4----- R2-------R4-----
: : : :
: : : :
Figure 40: multi-as-aggregation Figure 33: Multi-AS aggregation
5. IANA Considerations 5. IANA Considerations
This document requests a code point from the registry of Address This document requests a code point from the registry of Address
Family Numbers. Family Numbers. As per early allocation procedure this is AFI 16388.
This document requests a code point from the registry of Subsequent
Address Family Numbers. As per early allocation procedure this is
SAFI 71.
This document requests a code point from the BGP Path Attributes This document requests a code point from the BGP Path Attributes
registry. registry.
This document requests creation of a new registry for node anchor, This document requests creation of a new registry for node anchor,
link descriptor and link attribute TLVs. Values 0-255 are reserved. link descriptor and link attribute TLVs. Values 0-255 are reserved.
Values 256-65535 will be used for Codepoints. The registry will be Values 256-65535 will be used for Codepoints. The registry will be
initialized as shown in Table 2 and Table 4. Allocations within the initialized as shown in Table 11. Allocations within the registry
registry will require documentation of the proposed use of the will require documentation of the proposed use of the allocated value
allocated value and approval by the Designated Expert assigned by the and approval by the Designated Expert assigned by the IESG (see
IESG (see [RFC5226]). [RFC5226]).
Note to RFC Editor: this section may be removed on publication as an Note to RFC Editor: this section may be removed on publication as an
RFC. RFC.
6. Manageability Considerations 6. Manageability Considerations
This section is structured as recommended in [RFC5706]. This section is structured as recommended in [RFC5706].
6.1. Operational Considerations 6.1. Operational Considerations
6.1.1. Operations 6.1.1. Operations
Existing BGP operation procedures apply. No new operation procedures Existing BGP operational procedures apply. No new operation
are defined in this document. It shall be noted that the NLRI procedures are defined in this document. It is noted that the NLRI
information present in this document purely carries application level information present in this document purely carries application level
data that have no immediate corresponding forwarding state impact. data that has no immediate corresponding forwarding state impact. As
As such, any churn in reachability information has different impact such, any churn in reachability information has different impact than
than regular BGP update which needs to change forwarding state for an regular BGP updates which need to change forwarding state for an
entire router. Furthermore it is anticipated that distribution of entire router. Furthermore it is anticipated that distribution of
this NLRI will be handled by dedicated route-reflectors providing a this NLRI will be handled by dedicated route-reflectors providing a
level of isolation and fault-containment between different NLRI level of isolation and fault-containment between different NLRI
types. types.
6.1.2. Installation and Initial Setup 6.1.2. Installation and Initial Setup
Configuration parameters defined in Section 6.2.3 SHOULD be Configuration parameters defined in Section 6.2.3 SHOULD be
initialized to the following default values: initialized to the following default values:
skipping to change at page 37, line 38 skipping to change at page 36, line 38
rate at which Link State NLRIs will be advertised/withdrawn from rate at which Link State NLRIs will be advertised/withdrawn from
neighbors neighbors
An implementation SHOULD allow the operator to specify the maximum An implementation SHOULD allow the operator to specify the maximum
number of Link State NLRIs stored in router's RIB. number of Link State NLRIs stored in router's RIB.
An implementation SHOULD allow the operator to create abstracted An implementation SHOULD allow the operator to create abstracted
topologies that are advertised to neighbors; Create different topologies that are advertised to neighbors; Create different
abstractions for different neighbors. abstractions for different neighbors.
An implementation SHOULD allow the operator to configure a 64-bit
instance ID.
An implementation SHOULD allow the operator to configure a pair of An implementation SHOULD allow the operator to configure a pair of
ASN and BGP identifier per flooding set the node participates in. ASN and BGP-LS identifier per flooding set the node participates in.
6.2.4. Accounting Management 6.2.4. Accounting Management
Not Applicable. Not Applicable.
6.2.5. Performance Management 6.2.5. Performance Management
An implementation SHOULD provide the following statistics: An implementation SHOULD provide the following statistics:
o Total number of Link-State NLRI updates sent/received o Total number of Link-State NLRI updates sent/received
skipping to change at page 38, line 14 skipping to change at page 37, line 19
o Number of errored received Link-State NLRI updates, per neighbor o Number of errored received Link-State NLRI updates, per neighbor
o Total number of locally originated Link-State NLRIs o Total number of locally originated Link-State NLRIs
6.2.6. Security Management 6.2.6. Security Management
An operator SHOULD define ACLs to limit inbound updates as follows: An operator SHOULD define ACLs to limit inbound updates as follows:
o Drop all updates from Consumer peers o Drop all updates from Consumer peers
7. TLV/SubTLV Code Points Summary 7. TLV/Sub-TLV Code Points Summary
This section contains the global table of all TLVs/SubTLVs defined in This section contains the global table of all TLVs/Sub-TLVs defined
this document. in this document.
+------------+--------------------+---------------+-----------------+ +-----------+---------------------+---------------+-----------------+
| TLV/SubTLV | Description | IS-IS | Value defined | | TLV Code | Description | IS-IS TLV/ | Value defined |
| | | TLV/Sub-TLV | in: | | Point | | Sub-TLV | in: |
+------------+--------------------+---------------+-----------------+ +-----------+---------------------+---------------+-----------------+
| 256 | Identifier | -- | Section 3.2.1 | | 256 | Local Node | --- | Section 3.2.1.2 |
| 257 | Local Node | -- | Section 3.2.2.1 | | | Descriptors | | |
| | Descriptors | | | | 257 | Remote Node | --- | Section 3.2.1.3 |
| 258 | Remote Node | -- | Section 3.2.2.2 | | | Descriptors | | |
| | Descriptors | | | | 258 | Link Local/Remote | 22/4 | [RFC5307]/1.1 |
| 259 | Autonomous System | -- | Section 3.2.2.3 | | | Identifiers | | |
| 260 | BGP Identifier | -- | Section 3.2.2.3 | | 259 | IPv4 interface | 22/6 | [RFC5305]/3.2 |
| 261 | ISO Node-ID | -- | Section 3.2.2.3 | | | address | | |
| 262 | IPv4 Router-ID | -- | Section 3.2.2.3 | | 260 | IPv4 neighbor | 22/8 | [RFC5305]/3.3 |
| 263 | IPv6 Router-ID | -- | Section 3.2.2.3 | | | address | | |
| 264 | Link Local/Remote | 22/4 | [RFC5307]/1.1 | | 261 | IPv6 interface | 22/12 | [RFC6119]/4.2 |
| | Identifiers | | | | | address | | |
| 265 | IPv4 interface | 22/6 | [RFC5305]/3.2 | | 262 | IPv6 neighbor | 22/13 | [RFC6119]/4.3 |
| | address | | | | | address | | |
| 266 | IPv4 neighbor | 22/8 | [RFC5305]/3.3 | | 263 | Multi-Topology ID | --- | Section 3.2.1.5 |
| | address | | | | 264 | OSPF Route Type | --- | Section 3.2.3 |
| 267 | IPv6 interface | 22/12 | [RFC6119]/4.2 | | 265 | IP Reachability | --- | Section 3.2.3 |
| | address | | | | | Information | | |
| 268 | IPv6 neighbor | 22/13 | [RFC6119]/4.3 | | 512 | Autonomous System | --- | Section 3.2.1.4 |
| | address | | | | 513 | BGP-LS Identifier | --- | Section 3.2.1.4 |
| 256/5 | Multi Topology ID | -- | Section 3.2.1.5 | | 514 | Area ID | --- | Section 3.2.1.4 |
| 269 | Administrative | 22/3 | [RFC5305]/3.1 | | 515 | IGP Router-ID | --- | Section 3.2.1.4 |
| | group (color) | | | | 1024 | Node Flag Bits | --- | Section 3.3.1.1 |
| 270 | Maximum link | 22/9 | [RFC5305]/3.3 | | 1025 | Opaque Node | --- | Section 3.3.1.5 |
| | bandwidth | | | | | Properties | | |
| 271 | Max. reservable | 22/10 | [RFC5305]/3.5 | | 1026 | Node Name | variable | Section 3.3.1.3 |
| | link bandwidth | | | | 1027 | IS-IS Area | variable | Section 3.3.1.2 |
| 272 | Unreserved | 22/11 | [RFC5305]/3.6 | | | Identifier | | |
| | bandwidth | | | | 1028 | IPv4 Router-ID of | 134/--- | [RFC5305]/4.3 |
| 273 | TE Default Metric | 22/18 | [RFC5305]/3.7 | | | Local Node | | |
| 274 | Link Protection | 22/20 | [RFC5307]/1.2 | | 1029 | IPv6 Router-ID of | 140/--- | [RFC6119]/4.1 |
| | Type | | | | | Local Node | | |
| 275 | MPLS Protocol Mask | -- | Section 3.3.1.1 | | 1030 | IPv4 Router-ID of | 134/--- | [RFC5305]/4.3 |
| 276 | Metric | -- | Section 3.3.1.2 | | | Remote Node | | |
| 277 | Shared Risk Link | -- | Section 3.3.1.3 | | 1031 | IPv6 Router-ID of | 140/--- | [RFC6119]/4.1 |
| | Group | | | | | Remote Node | | |
| 278 | OSPF specific link | -- | Section 3.3.1.4 | | 1088 | Administrative | 22/3 | [RFC5305]/3.1 |
| | attribute | | | | | group (color) | | |
| 279 | IS-IS Specific | -- | Section 3.3.1.5 | | 1089 | Maximum link | 22/9 | [RFC5305]/3.3 |
| | Link Attribute | | | | | bandwidth | | |
| 280 | Node Flag Bits | -- | Section 3.3.2.2 | | 1090 | Max. reservable | 22/10 | [RFC5305]/3.5 |
| 281 | OSPF Specific Node | -- | Section 3.3.2.3 | | | link bandwidth | | |
| | Properties | | | | 1091 | Unreserved | 22/11 | [RFC5305]/3.6 |
| 282 | IS-IS Specific | -- | Section 3.3.2.4 | | | bandwidth | | |
| | Node Properties | | | | 1092 | TE Default Metric | 22/18 | [RFC5305]/3.7 |
| 283 | IGP Flags | -- | Section 3.3.3.1 | | 1093 | Link Protection | 22/20 | [RFC5307]/1.2 |
| 284 | Route Tag | -- | [RFC5130] | | | Type | | |
| 285 | Extended Tag | -- | [RFC5130] | | 1094 | MPLS Protocol Mask | --- | Section 3.3.2.2 |
| 286 | Prefix Metric | -- | [RFC5305] | | 1095 | Metric | --- | Section 3.3.2.3 |
| 287 | OSPF Forwarding | -- | [RFC2328] | | 1096 | Shared Risk Link | --- | Section 3.3.2.4 |
| | Address | | | | | Group | | |
+------------+--------------------+---------------+-----------------+ | 1097 | Opaque link | --- | Section 3.3.2.5 |
| | attribute | | |
| 1098 | Link Name attribute | --- | Section 3.3.2.6 |
| 1152 | IGP Flags | --- | Section 3.3.3.1 |
| 1153 | Route Tag | --- | [RFC5130] |
| 1154 | Extended Tag | --- | [RFC5130] |
| 1155 | Prefix Metric | --- | [RFC5305] |
| 1156 | OSPF Forwarding | --- | [RFC2328] |
| | Address | | |
| 1157 | Opaque Prefix | --- | Section 3.3.3.6 |
| | Attribute | | |
+-----------+---------------------+---------------+-----------------+
Table 10: Summary Table of TLV/SubTLV Codepoints Table 11: Summary Table of TLV/Sub-TLV Codepoints
8. Security Considerations 8. Security Considerations
Procedures and protocol extensions defined in this document do not Procedures and protocol extensions defined in this document do not
affect the BGP security model. affect the BGP security model. See
[I-D.ietf-karp-routing-tcp-analysis] for details.
A BGP Speaker SHOULD NOT accept updates from a Consumer peer. A BGP Speaker SHOULD NOT accept updates from a Consumer peer.
An operator SHOULD employ a mechanism to protect a BGP Speaker An operator SHOULD employ a mechanism to protect a BGP Speaker
against DDOS attacks from Consumers. against DDOS attacks from Consumers.
9. Contributors 9. Contributors
We would like to thank Robert Varga for the significant contribution We would like to thank Robert Varga for the significant contribution
he gave to this document. he gave to this document.
10. Acknowledgements 10. Acknowledgements
We would like to thank Nischal Sheth, Alia Atlas, David Ward, Derek We would like to thank Nischal Sheth, Alia Atlas, David Ward, Derek
Yeung, Murtuza Lightwala, John Scudder, Kaliraj Vairavakkalai, Les Yeung, Murtuza Lightwala, John Scudder, Kaliraj Vairavakkalai, Les
Ginsberg, Liem Nguyen, Manish Bhardwaj, Mike Shand, Peter Psenak, Rex Ginsberg, Liem Nguyen, Manish Bhardwaj, Mike Shand, Peter Psenak, Rex
Fernando, Richard Woundy, Steven Luong, Tamas Mondal, Waqas Alam, Fernando, Richard Woundy, Steven Luong, Tamas Mondal, Waqas Alam,
Vipin Kumar, Naiming Shen and Yakov Rekhter for their comments. Vipin Kumar, Naiming Shen, Balaji Rajagopalan and Yakov Rekhter for
their comments.
11. References 11. References
11.1. Normative References 11.1. Normative References
[RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and [RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and
dual environments", RFC 1195, December 1990. dual environments", RFC 1195, December 1990.
[RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and [RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and
E. Lear, "Address Allocation for Private Internets", E. Lear, "Address Allocation for Private Internets",
skipping to change at page 41, line 19 skipping to change at page 40, line 30
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998. [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998.
[RFC2545] Marques, P. and F. Dupont, "Use of BGP-4 Multiprotocol [RFC2545] Marques, P. and F. Dupont, "Use of BGP-4 Multiprotocol
Extensions for IPv6 Inter-Domain Routing", RFC 2545, Extensions for IPv6 Inter-Domain Routing", RFC 2545,
March 1999. March 1999.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, December 2001. Tunnels", RFC 3209, December 2001.
[RFC3490] Faltstrom, P., Hoffman, P., and A. Costello,
"Internationalizing Domain Names in Applications (IDNA)",
RFC 3490, March 2003.
[RFC4202] Kompella, K. and Y. Rekhter, "Routing Extensions in [RFC4202] Kompella, K. and Y. Rekhter, "Routing Extensions in
Support of Generalized Multi-Protocol Label Switching Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC 4202, October 2005. (GMPLS)", RFC 4202, October 2005.
[RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway [RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway
Protocol 4 (BGP-4)", RFC 4271, January 2006. Protocol 4 (BGP-4)", RFC 4271, January 2006.
[RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter, [RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
"Multiprotocol Extensions for BGP-4", RFC 4760, "Multiprotocol Extensions for BGP-4", RFC 4760,
January 2007. January 2007.
skipping to change at page 41, line 49 skipping to change at page 41, line 17
Intermediate Systems (IS-ISs)", RFC 5120, February 2008. Intermediate Systems (IS-ISs)", RFC 5120, February 2008.
[RFC5130] Previdi, S., Shand, M., and C. Martin, "A Policy Control [RFC5130] Previdi, S., Shand, M., and C. Martin, "A Policy Control
Mechanism in IS-IS Using Administrative Tags", RFC 5130, Mechanism in IS-IS Using Administrative Tags", RFC 5130,
February 2008. February 2008.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226, IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008. May 2008.
[RFC5301] McPherson, D. and N. Shen, "Dynamic Hostname Exchange
Mechanism for IS-IS", RFC 5301, October 2008.
[RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic
Engineering", RFC 5305, October 2008. Engineering", RFC 5305, October 2008.
[RFC5307] Kompella, K. and Y. Rekhter, "IS-IS Extensions in Support [RFC5307] Kompella, K. and Y. Rekhter, "IS-IS Extensions in Support
of Generalized Multi-Protocol Label Switching (GMPLS)", of Generalized Multi-Protocol Label Switching (GMPLS)",
RFC 5307, October 2008. RFC 5307, October 2008.
[RFC6119] Harrison, J., Berger, J., and M. Bartlett, "IPv6 Traffic [RFC6119] Harrison, J., Berger, J., and M. Bartlett, "IPv6 Traffic
Engineering in IS-IS", RFC 6119, February 2011. Engineering in IS-IS", RFC 6119, February 2011.
[RFC6286] Chen, E. and J. Yuan, "Autonomous-System-Wide Unique BGP
Identifier for BGP-4", RFC 6286, June 2011.
[RFC6822] Previdi, S., Ginsberg, L., Shand, M., Roy, A., and D. [RFC6822] Previdi, S., Ginsberg, L., Shand, M., Roy, A., and D.
Ward, "IS-IS Multi-Instance", RFC 6822, December 2012. Ward, "IS-IS Multi-Instance", RFC 6822, December 2012.
11.2. Informative References 11.2. Informative References
[I-D.ietf-alto-protocol] [I-D.ietf-alto-protocol]
Alimi, R., Penno, R., and Y. Yang, "ALTO Protocol", Alimi, R., Penno, R., and Y. Yang, "ALTO Protocol",
draft-ietf-alto-protocol-13 (work in progress), draft-ietf-alto-protocol-13 (work in progress),
September 2012. September 2012.
[I-D.ietf-karp-routing-tcp-analysis]
Jethanandani, M., Patel, K., and L. Zheng, "Analysis of
BGP, LDP, PCEP and MSDP Issues According to KARP Design
Guide", draft-ietf-karp-routing-tcp-analysis-07 (work in
progress), April 2013.
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", RFC 4655, August 2006. Element (PCE)-Based Architecture", RFC 4655, August 2006.
[RFC4970] Lindem, A., Shen, N., Vasseur, JP., Aggarwal, R., and S. [RFC4970] Lindem, A., Shen, N., Vasseur, JP., Aggarwal, R., and S.
Shaffer, "Extensions to OSPF for Advertising Optional Shaffer, "Extensions to OSPF for Advertising Optional
Router Capabilities", RFC 4970, July 2007. Router Capabilities", RFC 4970, July 2007.
[RFC5073] Vasseur, J. and J. Le Roux, "IGP Routing Protocol [RFC5073] Vasseur, J. and J. Le Roux, "IGP Routing Protocol
Extensions for Discovery of Traffic Engineering Node Extensions for Discovery of Traffic Engineering Node
Capabilities", RFC 5073, December 2007. Capabilities", RFC 5073, December 2007.
[RFC5152] Vasseur, JP., Ayyangar, A., and R. Zhang, "A Per-Domain [RFC5152] Vasseur, JP., Ayyangar, A., and R. Zhang, "A Per-Domain
Path Computation Method for Establishing Inter-Domain Path Computation Method for Establishing Inter-Domain
Traffic Engineering (TE) Label Switched Paths (LSPs)", Traffic Engineering (TE) Label Switched Paths (LSPs)",
skipping to change at page 42, line 38 skipping to change at page 42, line 17
[RFC5073] Vasseur, J. and J. Le Roux, "IGP Routing Protocol [RFC5073] Vasseur, J. and J. Le Roux, "IGP Routing Protocol
Extensions for Discovery of Traffic Engineering Node Extensions for Discovery of Traffic Engineering Node
Capabilities", RFC 5073, December 2007. Capabilities", RFC 5073, December 2007.
[RFC5152] Vasseur, JP., Ayyangar, A., and R. Zhang, "A Per-Domain [RFC5152] Vasseur, JP., Ayyangar, A., and R. Zhang, "A Per-Domain
Path Computation Method for Establishing Inter-Domain Path Computation Method for Establishing Inter-Domain
Traffic Engineering (TE) Label Switched Paths (LSPs)", Traffic Engineering (TE) Label Switched Paths (LSPs)",
RFC 5152, February 2008. RFC 5152, February 2008.
[RFC5316] Chen, M., Zhang, R., and X. Duan, "ISIS Extensions in
Support of Inter-Autonomous System (AS) MPLS and GMPLS
Traffic Engineering", RFC 5316, December 2008.
[RFC5392] Chen, M., Zhang, R., and X. Duan, "OSPF Extensions in
Support of Inter-Autonomous System (AS) MPLS and GMPLS
Traffic Engineering", RFC 5392, January 2009.
[RFC5693] Seedorf, J. and E. Burger, "Application-Layer Traffic [RFC5693] Seedorf, J. and E. Burger, "Application-Layer Traffic
Optimization (ALTO) Problem Statement", RFC 5693, Optimization (ALTO) Problem Statement", RFC 5693,
October 2009. October 2009.
[RFC5706] Harrington, D., "Guidelines for Considering Operations and [RFC5706] Harrington, D., "Guidelines for Considering Operations and
Management of New Protocols and Protocol Extensions", Management of New Protocols and Protocol Extensions",
RFC 5706, November 2009. RFC 5706, November 2009.
[RFC6286] Chen, E. and J. Yuan, "Autonomous-System-Wide Unique BGP
Identifier for BGP-4", RFC 6286, June 2011.
[RFC6549] Lindem, A., Roy, A., and S. Mirtorabi, "OSPFv2 Multi- [RFC6549] Lindem, A., Roy, A., and S. Mirtorabi, "OSPFv2 Multi-
Instance Extensions", RFC 6549, March 2012. Instance Extensions", RFC 6549, March 2012.
Authors' Addresses Authors' Addresses
Hannes Gredler Hannes Gredler
Juniper Networks, Inc. Juniper Networks, Inc.
1194 N. Mathilda Ave. 1194 N. Mathilda Ave.
Sunnyvale, CA 94089 Sunnyvale, CA 94089
US US
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