--- 1/draft-ietf-idr-ls-distribution-01.txt 2013-02-26 03:31:53.351709277 +0100 +++ 2/draft-ietf-idr-ls-distribution-02.txt 2013-02-26 03:31:53.419757453 +0100 @@ -1,24 +1,24 @@ Inter-Domain Routing H. Gredler Internet-Draft Juniper Networks, Inc. Intended status: Standards Track J. Medved -Expires: April 25, 2013 S. Previdi +Expires: August 28, 2013 S. Previdi Cisco Systems, Inc. A. Farrel Juniper Networks, Inc. S. Ray Cisco Systems, Inc. - October 22, 2012 + February 24, 2013 North-Bound Distribution of Link-State and TE Information using BGP - draft-ietf-idr-ls-distribution-01 + draft-ietf-idr-ls-distribution-02 Abstract In a number of environments, a component external to a network is called upon to perform computations based on the network topology and current state of the connections within the network, including traffic engineering information. This is information typically distributed by IGP routing protocols within the network This document describes a mechanism by which links state and traffic @@ -45,25 +45,25 @@ Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." - This Internet-Draft will expire on April 25, 2013. + This Internet-Draft will expire on August 28, 2013. Copyright Notice - Copyright (c) 2012 IETF Trust and the persons identified as the + Copyright (c) 2013 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as @@ -71,56 +71,59 @@ Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Motivation and Applicability . . . . . . . . . . . . . . . . . 5 2.1. MPLS-TE with PCE . . . . . . . . . . . . . . . . . . . . . 5 2.2. ALTO Server Network API . . . . . . . . . . . . . . . . . 7 3. Carrying Link State Information in BGP . . . . . . . . . . . . 8 3.1. TLV Format . . . . . . . . . . . . . . . . . . . . . . . . 8 3.2. The Link State NLRI . . . . . . . . . . . . . . . . . . . 9 - 3.2.1. Node Descriptors . . . . . . . . . . . . . . . . . . . 11 - 3.2.2. Link Descriptors . . . . . . . . . . . . . . . . . . . 15 - 3.2.3. The Prefix NLRI . . . . . . . . . . . . . . . . . . . 16 - 3.3. The LINK_STATE Attribute . . . . . . . . . . . . . . . . . 16 - 3.3.1. Link Attribute TLVs . . . . . . . . . . . . . . . . . 16 - 3.3.2. Node Attribute TLVs . . . . . . . . . . . . . . . . . 20 - 3.3.3. Prefix Attributes TLVs . . . . . . . . . . . . . . . . 23 - 3.4. BGP Next Hop Information . . . . . . . . . . . . . . . . . 27 - 3.5. Inter-AS Links . . . . . . . . . . . . . . . . . . . . . . 27 - 4. Link to Path Aggregation . . . . . . . . . . . . . . . . . . . 27 - 4.1. Example: No Link Aggregation . . . . . . . . . . . . . . . 27 - 4.2. Example: ASBR to ASBR Path Aggregation . . . . . . . . . . 28 - 4.3. Example: Multi-AS Path Aggregation . . . . . . . . . . . . 28 - 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 29 - 6. Manageability Considerations . . . . . . . . . . . . . . . . . 29 - 6.1. Operational Considerations . . . . . . . . . . . . . . . . 29 - 6.1.1. Operations . . . . . . . . . . . . . . . . . . . . . . 29 - 6.1.2. Installation and Initial Setup . . . . . . . . . . . . 30 - 6.1.3. Migration Path . . . . . . . . . . . . . . . . . . . . 30 + 3.2.1. Identifier TLV . . . . . . . . . . . . . . . . . . . . 12 + 3.2.2. Node Descriptors . . . . . . . . . . . . . . . . . . . 14 + 3.2.3. Link Descriptors . . . . . . . . . . . . . . . . . . . 22 + 3.2.4. Prefix Descriptors . . . . . . . . . . . . . . . . . . 23 + 3.3. The LINK_STATE Attribute . . . . . . . . . . . . . . . . . 23 + 3.3.1. Link Attribute TLVs . . . . . . . . . . . . . . . . . 24 + 3.3.2. Node Attribute TLVs . . . . . . . . . . . . . . . . . 27 + 3.3.3. Prefix Attributes TLVs . . . . . . . . . . . . . . . . 29 + 3.4. BGP Next Hop Information . . . . . . . . . . . . . . . . . 33 + 3.5. Inter-AS Links . . . . . . . . . . . . . . . . . . . . . . 33 + 4. Link to Path Aggregation . . . . . . . . . . . . . . . . . . . 33 + 4.1. Example: No Link Aggregation . . . . . . . . . . . . . . . 34 + 4.2. Example: ASBR to ASBR Path Aggregation . . . . . . . . . . 34 + 4.3. Example: Multi-AS Path Aggregation . . . . . . . . . . . . 35 + 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 35 + 6. Manageability Considerations . . . . . . . . . . . . . . . . . 35 + 6.1. Operational Considerations . . . . . . . . . . . . . . . . 35 + 6.1.1. Operations . . . . . . . . . . . . . . . . . . . . . . 36 + 6.1.2. Installation and Initial Setup . . . . . . . . . . . . 36 + 6.1.3. Migration Path . . . . . . . . . . . . . . . . . . . . 36 6.1.4. Requirements on Other Protocols and Functional - Components . . . . . . . . . . . . . . . . . . . . . . 30 - 6.1.5. Impact on Network Operation . . . . . . . . . . . . . 30 - 6.1.6. Verifying Correct Operation . . . . . . . . . . . . . 30 - 6.2. Management Considerations . . . . . . . . . . . . . . . . 31 - 6.2.1. Management Information . . . . . . . . . . . . . . . . 31 - 6.2.2. Fault Management . . . . . . . . . . . . . . . . . . . 31 - 6.2.3. Configuration Management . . . . . . . . . . . . . . . 31 - 6.2.4. Accounting Management . . . . . . . . . . . . . . . . 31 - 6.2.5. Performance Management . . . . . . . . . . . . . . . . 31 - 6.2.6. Security Management . . . . . . . . . . . . . . . . . 32 - 7. Security Considerations . . . . . . . . . . . . . . . . . . . 32 - 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 32 - 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 32 - 9.1. Normative References . . . . . . . . . . . . . . . . . . . 32 - 9.2. Informative References . . . . . . . . . . . . . . . . . . 34 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 34 + Components . . . . . . . . . . . . . . . . . . . . . . 36 + 6.1.5. Impact on Network Operation . . . . . . . . . . . . . 36 + 6.1.6. Verifying Correct Operation . . . . . . . . . . . . . 37 + 6.2. Management Considerations . . . . . . . . . . . . . . . . 37 + 6.2.1. Management Information . . . . . . . . . . . . . . . . 37 + 6.2.2. Fault Management . . . . . . . . . . . . . . . . . . . 37 + 6.2.3. Configuration Management . . . . . . . . . . . . . . . 37 + 6.2.4. Accounting Management . . . . . . . . . . . . . . . . 37 + 6.2.5. Performance Management . . . . . . . . . . . . . . . . 37 + 6.2.6. Security Management . . . . . . . . . . . . . . . . . 38 + 7. TLV/SubTLV Code Points Summary . . . . . . . . . . . . . . . . 38 + 8. Security Considerations . . . . . . . . . . . . . . . . . . . 40 + 9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 40 + 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 40 + 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 40 + 11.1. Normative References . . . . . . . . . . . . . . . . . . . 40 + 11.2. Informative References . . . . . . . . . . . . . . . . . . 42 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 43 1. Introduction The contents of a Link State Database (LSDB) or a Traffic Engineering Database (TED) has the scope of an IGP area. Some applications, such as end-to-end Traffic Engineering (TE), would benefit from visibility outside one area or Autonomous System (AS) in order to make better decisions. The IETF has defined the Path Computation Element (PCE) [RFC4655] as @@ -265,22 +268,23 @@ to be collected from the IGP within the network, filtered according to configurable policy, and distributed to the PCE as necessary. 2.2. ALTO Server Network API An ALTO Server [RFC5693] is an entity that generates an abstracted network topology and provides it to network-aware applications over a web service based API. Example applications are p2p clients or trackers, or CDNs. The abstracted network topology comes in the form of two maps: a Network Map that specifies allocation of prefixes to - PIDs, and a Cost Map that specifies the cost between PIDs listed in - the Network Map. For more details, see [I-D.ietf-alto-protocol]. + Partition Identifiers (PIDs), and a Cost Map that specifies the cost + between PIDs listed in the Network Map. For more details, see + [I-D.ietf-alto-protocol]. ALTO abstract network topologies can be auto-generated from the physical topology of the underlying network. The generation would typically be based on policies and rules set by the operator. Both prefix and TE data are required: prefix data is required to generate ALTO Network Maps, TE (topology) data is required to generate ALTO Cost Maps. Prefix data is carried and originated in BGP, TE data is originated and carried in an IGP. The mechanism defined in this document provides a single interface through which an ALTO Server can retrieve all the necessary prefix and network topology data from the @@ -301,52 +305,53 @@ +--------+ | | | | | | +--------+ +---------+ +--------+ | | Client |<--+ +--------+ Figure 3: ALTO Server using network topology information 3. Carrying Link State Information in BGP - Two parts: a new BGP NLRI that describes links and nodes comprising - IGP link state information, and a new BGP path attribute that carries - link and node properties and attributes, such as the link metric or - node properties. + This specification contains two parts: definition of a new BGP NLRI + that describes links, nodes and prefixes comprising IGP link state + information, and definition of a new BGP path attribute that carries + link, node and prefix properties and attributes, such as the link and + prefix metric or node properties. 3.1. TLV Format Information in the new link state NLRIs and attributes is encoded in Type/Length/Value triplets. The TLV format is shown in Figure 4. 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | Value (variable) | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 4: TLV format 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 - TLV is not padded to four-octet alignment; Unrecognized types are + TLV is not padded to four-octet alignment. Unrecognized types are ignored. 3.2. The Link State NLRI The MP_REACH and MP_UNREACH attributes are BGP's containers for carrying opaque information. Each Link State NLRI describes either a - single node or link. + node, a link or a prefix. All link, node and prefix information SHALL be encoded using a TBD AFI / TBD SAFI header into those attributes. In order for two BGP speakers to exchange Link-State NLRI, they MUST use BGP Capabilities Advertisement to ensure that they both are capable of properly processing such NLRI. This is done as specified in [RFC4760], by using capability code 1 (multi-protocol BGP), with an AFI/SAFI TBD. @@ -355,824 +360,1143 @@ 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | NLRI Type | Total NLRI Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | Link-State NLRI (variable) | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - Figure 5: Link State SAFI 1 NLRI Format + Figure 5: Link State SAFI (TBD) NLRI Format 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | NLRI Type | Total NLRI Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | + Route Distinguisher + | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | Link-State NLRI (variable) | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 6: Link State SAFI 128 NLRI Format - The 'Total NLRI Length' field contains the cumulative length of all - the TLVs in the NLRI. For VPN applications it also includes the - length of the Route Distinguisher. + The 'Total NLRI Length' field contains the cumulative length of rest + of the NLRI not including the NLRI Type field or itself. For VPN + applications it also includes the length of the Route Distinguisher. The 'NLRI Type' field can contain one of the following values: Type = 1: Link NLRI, contains link descriptors and link attributes Type = 2: Node NLRI, contains node attributes Type = 3: IPv4 Topology Prefix NLRI Type = 4: IPv6 Topology Prefix NLRI The Link NLRI (NLRI Type = 1) is shown in the following figure. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | Protocol-ID | Reserved | Instance Identifier | + | Protocol-ID | Reserved | | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + | Identifier (variable) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Local Node Descriptors (variable) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Remote Node Descriptors (variable) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Link Descriptors (variable) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 7: The Link NLRI format The Node NLRI (NLRI Type = 2) is shown in the following figure. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | Protocol-ID | Reserved | Instance Identifier | + | Protocol-ID | Reserved | | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + | Identifier (variable) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Local Node Descriptors (variable) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 8: The Node NLRI format The IPv4 and IPv6 Prefix NLRIs (NLRI Type = 3 and Type = 4) use the same format as shown in the following figure. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | Protocol-ID | Reserved | Instance Identifier | + | Protocol-ID | Reserved | | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + | Identifier (variable) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | Node Descriptor | + | Local Node Descriptor (variable) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | Prefix NLRI (variable) | + | Reachability information (variable; one or more prefixes) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 9: The IPv4/IPv6 Topology Prefix NLRI format The 'Protocol-ID' field can contain one of the following values: Protocol-ID = 0: Unknown, The source of NLRI information could not be determined - Protocol-ID: IS-IS Level 1, The NLRI information has been sourced - by IS-IS Level 1 + Protocol-ID = 1: IS-IS Level 1, The NLRI information has been + sourced by IS-IS Level 1 - Protocol-ID: IS-IS Level 2, The NLRI information has been sourced - by IS-IS Level 2 + Protocol-ID = 2: IS-IS Level 2, The NLRI information has been + sourced by IS-IS Level 2 Protocol-ID = 3: OSPF, The NLRI information has been sourced by OSPF Protocol-ID = 4: Direct, The NLRI information has been sourced from local interface state Protocol-ID = 5: Static, The NLRI information has been sourced by static configuration Both OSPF and IS-IS may run multiple routing protocol instances over - the same link. See [I-D.ietf-isis-mi] and [RFC6549]. The 'Instance - Identifier' field identifies the protocol instance. + the same link. See [RFC6822] and [RFC6549]. + + Identifier TLV is a mandatory TLV containing identifiers of the NLRI + and used to associate the NLRI to an instance, a domain, an area or a + prefix. Each Node Descriptor and Link Descriptor consists of one or more TLVs described in the following sections. The sender of an UPDATE message MUST order the TLVs within a Node Descriptor or a Link Descriptor in - ascending order of TLV type." + ascending order of TLV type. -3.2.1. Node Descriptors +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: + + Type: 4 + Length: 1 + + Figure 14: OSPF Route Type Sub-TLV Format + + OSPF Route Type can be either: Intra-Area (0x1), Inter-Area (0x2), + 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 + + The Multi Topology ID SubTLV (type: 5) carries the Multi Topology ID + for the link, node or prefix. The semantics of the Multi Topology ID + are defined in RFC5120, Section 7.2 [RFC5120], and the OSPF Multi + Topology ID), defined in RFC4915, Section 3.7 [RFC4915]. If the + value in the Multi Topology ID TLV is derived from OSPF, then the + upper 9 bits of the Multi Topology ID are set to 0. + + 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 | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + |R R R R| Multi Topology ID | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + Figure 15: Multi Topology ID SubTLV format + + The Multi Topology Identifier SubTLV is present in any NLRI Type. + +3.2.2. Node Descriptors Each link gets anchored by at least a pair of router-IDs. Since there are many Router-IDs formats (32 Bit IPv4 router-ID, 56 Bit ISO Node-ID and 128 Bit IPv6 router-ID) a link may be anchored by more than one Router-ID pair. The set of Local and Remote Node Descriptors describe which Protocols Router-IDs will be following to "anchor" the link described by the "Link attribute TLVs". There must be at least one "like" router-ID pair of a Local Node Descriptors and a Remote Node Descriptors per-protocol. If a peer sends an illegal 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 are globally unique. However there may be router-ID spaces (e.g. ISO) where not even a global registry exists, or worse, Router-IDs have been allocated following private-IP RFC 1918 [RFC1918] - allocation. In order to disambiguate the Router-IDs the local and - remote Autonomous System number TLVs of the anchor nodes MUST be - included in the NLRI. If the anchor node's AS is a member of an AS - Confederation ([RFC5065]), then the Autonomous System number TLV - contains the confederations' AS Confederation Identifier and the - Member-AS TLV is included in the NLRI. The Local and Remote - Autonomous System TLVs are 4 octets wide as described in [RFC4893]. - 2-octet AS Numbers SHALL be expanded to 4-octet AS Numbers by zeroing - the two MSB octets. + 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. -3.2.1.1. Local Node Descriptors +3.2.2.1. Local Node Descriptors - The Local Node Descriptors TLV (Type 256) contains Node Descriptors + The Local Node Descriptors TLV (Type 257) contains Node Descriptors for the node anchoring the local end of the link. The length of this TLV is variable. The value contains one or more Node Descriptor Sub- - TLVs defined in Section 3.2.1.3. + TLVs defined in Section 3.2.2.3. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | Node Descriptor Sub-TLVs (variable) | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - Figure 10: Local Node Descriptors TLV format + Figure 16: Local Node Descriptors TLV format -3.2.1.2. Remote Node Descriptors +3.2.2.2. Remote Node Descriptors - The Remote Node Descriptors TLV (Type 257) contains Node Descriptors + The Remote Node Descriptors TLV (Type 258) contains Node Descriptors for the node anchoring the remote end of the link. The length of this TLV is variable. The value contains one or more Node Descriptor - Sub-TLVs defined in Section 3.2.1.3. + Sub-TLVs defined in Section 3.2.2.3. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | Node Descriptor Sub-TLVs (variable) | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - Figure 11: Remote Node Descriptors TLV format + Figure 17: Remote Node Descriptors TLV format -3.2.1.3. Node Descriptor Sub-TLVs +3.2.2.3. Node Descriptor Sub-TLVs The Node Descriptor Sub-TLV type codepoints and lengths are listed in the following table: - +------+-------------------+--------+ - | Type | Description | Length | - +------+-------------------+--------+ - | 258 | Autonomous System | 4 | - | 259 | Member-AS | 4 | - | 260 | ISO Node-ID | 7 | - | 261 | IPv4 Router-ID | 5 | - | 262 | IPv4 Router-ID | 17 | - +------+-------------------+--------+ + +------------+-------------------+----------+ + | TLV/SubTLV | Description | Length | + +------------+-------------------+----------+ + | 259 | Autonomous System | 4 | + | 260 | BGP Identifier | 4 | + | 261 | ISO Node-ID | 7 | + | 262 | IPv4 Router-ID | variable | + | 263 | IPv6 Router-ID | 16 | + +------------+-------------------+----------+ Table 1: Node Descriptor Sub-TLVs The TLV values in Node Descriptor Sub-TLVs are defined as follows: - Autonomous System: opaque value (32 Bit AS ID) + Autonomous System: opaque value (32 Bit AS Number) - Member-AS: opaque value (32 Bit AS ID); only included if the node is - in an AS confederation. + BGP-Identifier: opaque value (32 Bit AS ID); uniquely identifying + the BGP-LS speaker within an AS. IPv4 Router ID: opaque value (can be an IPv4 address or an 32 Bit - router ID). + router ID). When encoding an OSPF Designated Router ID, the + length is 8 (first 4 bytes is the Router-ID originating the Type-2 + LSA and next 4 bytes are taken from the Type-2 LSA ID). In other + cases, the length is 4. IPv6 Router ID: opaque value (can be an IPv6 address or 128 Bit router ID). 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 258 - and 259 specify administrative context in which TLVs 260-262 are - to be evaluated. The first TLV from range 260-262 is to be - interpreted as the primary node identifier, e.g. it acts as the - unique key 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. + 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. -3.2.1.4. Router-ID Anchoring Example: ISO Pseudonode +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 + disjoint parts, each running an independent IGP domain. + + IGP domain 1 IGP domain 2 + AS 1 AS 1 + +---+ +---+ + | | | | + +---+ +---+ + \ / + +---------+ + | | + +---------+ + Transit AS + + Figure 18: Stub-ASs or non-contiguous AS + + Using ASN to globally identify IGP node may break requirement (B). + + (ii) It is possible to run the same IGP domain across multiple AS. + + +----------------------+ + | +------+ +------+ | + | | AS 1 | | AS 2 | | + | +------+ +------+ | + +----------------------+ + IGP domain + + Figure 19: IGP Domain + + Using ASN to globally identify IGP node will break requirement (A). + + (iii) It is possible to run IGP across member-ASs in a confederation. + + +-------------------------------+ + | +--------------------------+ | + | | +--------+ +--------+ | | + | | | member | | member | | | + | | | AS 1 | | AS 2 | | | + | | +--------+ +--------+ | | + | +--------------------------+ | + | IGP domain | + +-------------------------------+ + Confederation (confed-id 1) + + Figure 20: Confederation + + Using a Confederation/MemberAS identifier to globally identify IGP + node will break requirement (A). + + (iv) It is possible to run more than one IGP domain within an AS by + setting up "transit BGP speakers". + + +---------------------------------+ + | +----------+ +----------+ | + | | IGP | +---+ | IGP | | + | | domain 1 +-+ +-+ domain 2 | | + | +----------+ +---+ +----------+ | + | ^ | + | | | + | Transit BGP node | + +---------------------------------+ + AS 1 + + Figure 21: Transit BGP Node + + Using ASN to globally identify IGP node may break requirement (A). + + In summary, there is no strict relation between BGP AS division and + 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 + 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 + flooding set. + + Case b) There is one BGP LS speaker running on one node in the + flooding set. + + Case c) There is more than one BGP LS speakers running on the nodes + in the flooding set. + + For Case a), the nodes in that flooding set do not appear in BGP LS + 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 + speakers within one IGP domain. + + Now we make an observation that simplifies the task: it is sufficient + to have a unique "string" per flooding set. + + When we have a unique string per flooding set, then two nodes in + 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 as the string. + + The combination of is globally + unique, as per [RFC6286]. + + For Case b), which is the simplest BGP-LS deployment scenario, this + approach requires no additional configuration from the user. + + For Case c), however, if each BGP-LS speaker in the given flooding + set attaches its own , 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 + combination of the "chosen speaker". + + When an IGP node belongs to two or more flooding sets, it views + 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 + N1 N0 N2 + +---+ link1 +---+ link 2 +---+ + | +-------+ +---------+ | + +---+ +---+ +---+ + |<- Level 1 ->| |<- level 2 ->| + L11 L12 + "str1" "str2" + + Figure 22: IGP Node in multiple flooding sets + + The node N0 is a level 1-2 node. Link1 belongs to level 1 area L11, + 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 and + . + + To sum up, the mechanism works as follows: + + 1. We use as the + disambiguating string. + + 2. By default, a BGP-LS speaker uses its own ASN, BGP identifier + (router-id) for these fields for the NLRIs it originates. + + 3. Operator has the ability to configure other per + flooding set the IGP node underneath belongs to. In that case, + the node descriptor(s) for a given NLRI uses the string + corresponding to the flooding set where the node belongs. + + The operator needs to provide the configuration if there are multiple + BGP-LS speakers running in the same flooding set. + +3.2.2.5. Router-ID Anchoring Example: ISO Pseudonode IS-IS Pseudonodes are a good example for the variable Router-ID - anchoring. Consider Figure 12. This represents a Broadcast LAN + 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 ISO node-ID and remote ISO node-id) The NLRI for (Pseudonode1, Node2) encodes a local ISO node-ID and remote ISO node-id. +-----------------+ +-----------------+ +-----------------+ | Node1 | | Pseudonode 1 | | Node2 | - |1920.0000.2001.00|--->|1921.6800.1001.02|--->|1920.0000.2002.00| + |1920.0000.2001.00|--->|1920.0000.2001.02|--->|1920.0000.2002.00| | 192.0.2.1 | | | | 192.0.2.2 | +-----------------+ +-----------------+ +-----------------+ - Figure 12: IS-IS Pseudonodes + Figure 23: IS-IS Pseudonodes -3.2.1.5. Router-ID Anchoring Example: OSPFv2 to IS-IS Migration +3.2.2.6. Router-ID Anchoring Example: OSPFv2 to IS-IS Migration Migrating gracefully from one IGP to another requires congruent operation of both routing protocols during the migration period. The target protocol (IS-IS) supports more router-ID spaces than the source (OSPFv2) protocol. When advertising a point-to-point link 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 router also supports the IPv6 traffic engineering extensions RFC 6119 + [RFC6119] for IS-IS. The NRLI encodes local IPv4 router-id, remote IPv4 router-id, remote ISO node-id and remote IPv6 node-id. -3.2.2. Link Descriptors +3.2.3. Link Descriptors The 'Link Descriptor' field is a set of Type/Length/Value (TLV) 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 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: - +------+------------------------+-----------------+-----------------+ - | Type | Description | IS-IS | Value defined | + +------------+--------------------+---------------+-----------------+ + | TLV/SubTLV | Description | IS-IS | Value defined | | | | TLV/Sub-TLV | in: | - +------+------------------------+-----------------+-----------------+ - | 263 | Link Local/Remote | 22/4 | [RFC5307]/1.1 | + +------------+--------------------+---------------+-----------------+ + | 264 | Link Local/Remote | 22/4 | [RFC5307]/1.1 | | | Identifiers | | | - | 264 | IPv4 interface address | 22/6 | [RFC5305]/3.2 | - | 265 | IPv4 neighbor address | 22/8 | [RFC5305]/3.3 | - | 266 | IPv6 interface address | 22/12 | [RFC6119]/4.2 | - | 267 | IPv6 neighbor address | 22/13 | [RFC6119]/4.3 | - | 268 | Multi Topology ID | --- | Section 3.2.2.1 | - +------+------------------------+-----------------+-----------------+ + | 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 -3.2.2.1. Multi Topology ID TLV +3.2.4. Prefix Descriptors - The Multi Topology ID TLV (Type 268) carries the Multi Topology ID - for this link. The semantics of the Multi Topology ID are defined in - RFC5120, Section 7.2 [RFC5120], and the OSPF Multi Topology ID), - defined in RFC4915, Section 3.7 [RFC4915]. If the value in the Multi - Topology ID TLV is derived from OSPF, then the upper 9 bits of the - Multi Topology ID are set to 0. + The 'Prefix descriptor' TLVs uniquely identify a Prefix (IPv4 or + IPv6) originated by a Node. - 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 | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - |R R R R| Multi Topology ID | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + The following Prefix descriptor TLVs are valid in the IPv4/IPv6 + Prefix NLRI: - Figure 13: Multi Topology ID TLV format + +------------+-----------------+-----------------+------------------+ + | TLV/SubTLV | Description | IS-IS | Value defined | + | | | TLV/Sub-TLV | in: | + +------------+-----------------+-----------------+------------------+ + | 256/5 | Multi Topology | --- | Section 3.2.1.5 | + | | ID | | | + +------------+-----------------+-----------------+------------------+ -3.2.3. The Prefix NLRI + Table 3: Prefix Descriptor TLVs - The Prefix NLRI is a variable length field that contains an IP - address prefix (IPv4 or IPv6) originally advertised in the IGP - topology. The distinction between IPv4 and IPv6 prefixes is given by - the NLRI Type filed in the Link State NLRI. Reachability information - is encoded as one or more 2-tuples of the form , - whose fields are described below: +3.2.4.1. The Prefix NLRI + + The Prefix NLRI is a variable length field that contains one or more + 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 , whose fields are described below: +---------------------------+ | Length (1 octet) | +---------------------------+ | Prefix (variable) | +---------------------------+ - Figure 14: Prefix NLRI format + Figure 24: Prefix NLRI format + + The 'Length' field contains the length of the prefix in bits. Only + the most significant octets of the prefix are encoded. 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. 3.3. The LINK_STATE Attribute - This is an optional, 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 NLRIs. + 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 NLRIs. 3.3.1. Link Attribute TLVs Each 'Link Attribute' is a Type/Length/Value (TLV) triplet formatted as defined in Section 3.1. The format and semantics of the 'value' fields in some 'Link Attribute' TLVs correspond to the format and semantics of value fields in IS-IS Extended IS Reachability sub-TLVs, defined in [RFC5305] and [RFC5307]. Other 'Link Attribute' TLVs are defined in this document. 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 attribute: - +------+-------------------------+----------------+-----------------+ - | Type | Description | IS-IS | Defined in: | + +------------+---------------------+--------------+-----------------+ + | TLV/SubTLV | Description | IS-IS | Defined in: | | | | TLV/Sub-TLV | | - +------+-------------------------+----------------+-----------------+ - | 269 | Administrative group | 22/3 | [RFC5305]/3.1 | - | | (color) | | | - | 270 | Maximum link bandwidth | 22/9 | [RFC5305]/3.3 | - | 271 | Max. reservable link | 22/10 | [RFC5305]/3.5 | + +------------+---------------------+--------------+-----------------+ + | 256/3 | Area Identifier | --- | Section 3.2.1.3 | + | 269 | Administrative | 22/3 | [RFC5305]/3.1 | + | | group (color) | | | + | 270 | Maximum link | 22/9 | [RFC5305]/3.3 | | | bandwidth | | | - | 272 | Unreserved bandwidth | 22/11 | [RFC5305]/3.6 | - | 273 | Link Protection Type | 22/20 | [RFC5307]/1.2 | - | 274 | MPLS Protocol Mask | --- | Section 3.3.1.1 | - | 275 | Metric | --- | Section 3.3.1.2 | - | 276 | Shared Risk Link Group | --- | Section 3.3.1.3 | - | 277 | OSPF specific link | --- | Section 3.3.1.4 | + | 271 | Max. reservable | 22/10 | [RFC5305]/3.5 | + | | link bandwidth | | | + | 272 | Unreserved | 22/11 | [RFC5305]/3.6 | + | | bandwidth | | | + | 273 | TE Default Metric | 22/18 | [RFC5305]/3.7 | + | 274 | Link Protection | 22/20 | [RFC5307]/1.2 | + | | Type | | | + | 275 | MPLS Protocol Mask | --- | Section 3.3.1.1 | + | 276 | Metric | --- | Section 3.3.1.2 | + | 277 | Shared Risk Link | --- | Section 3.3.1.3 | + | | Group | | | + | 278 | OSPF specific link | --- | Section 3.3.1.4 | | | attribute | | | - | 278 | IS-IS Specific Link | --- | Section 3.3.1.5 | + | 279 | IS-IS Specific Link | --- | Section 3.3.1.5 | | | Attribute | | | - | 279 | Area ID | --- | Section 3.3.1.6 | - +------+-------------------------+----------------+-----------------+ + +------------+---------------------+--------------+-----------------+ - Table 3: Link Attribute TLVs + Table 4: Link Attribute TLVs 3.3.1.1. MPLS Protocol Mask TLV - The MPLS Protocol TLV (Type 274) carries a bit mask describing which + The MPLS Protocol TLV (Type 275) 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 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |L R | +-+-+-+-+-+-+-+-+ - Figure 15: MPLS Protocol TLV + Figure 25: MPLS Protocol TLV The following bits are defined: +-----+---------------------------------------------+-----------+ | Bit | Description | Reference | +-----+---------------------------------------------+-----------+ | 0 | Label Distribution Protocol (LDP) | [RFC5036] | | 1 | Extension to RSVP for LSP Tunnels (RSVP-TE) | [RFC3209] | | 2-7 | Reserved for future use | | +-----+---------------------------------------------+-----------+ - Table 4: MPLS Protocol Mask TLV Codes + Table 5: MPLS Protocol Mask TLV Codes 3.3.1.2. Metric TLV - The IGP Metric TLV (Type 275) carries the metric for this link. The + The IGP Metric TLV (Type 276) carries the metric for this link. The length of this TLV is 3. If the length of the metric from which the IGP Metric value is derived is less than 3 (e.g. for OSPF link metrics or non-wide IS-IS metric), then the upper bits of the TLV are set to 0. 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IGP Link Metric | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - Figure 16: Metric TLV format + Figure 26: Metric TLV format 3.3.1.3. Shared Risk Link Group TLV - The Shared Risk Link Group (SRLG) TLV (Type 276) carries the Shared + The Shared Risk Link Group (SRLG) TLV (Type 277) carries the Shared Risk Link Group information (see Section 2.3, "Shared Risk Link Group Information", of [RFC4202]). It contains a data structure consisting of a (variable) list of SRLG values, where each element in the list - has 4 octets, as shown in Figure 17. The length of this TLV is 4 * + has 4 octets, as shown in Figure 27. The length of this TLV is 4 * (number of SRLG values). 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Shared Risk Link Group Value | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ............ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Shared Risk Link Group Value | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - Figure 17: Shared Risk Link Group TLV format + Figure 27: Shared Risk Link Group TLV format 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 (Type 138) defined in [RFC5307], and the IPv6 SRLG TLV (Type 139) defined in [RFC6119]. Since the Link State NLRI uses variable Router-ID anchoring, both IPv4 and IPv6 SRLG information can be carried in a single TLV. 3.3.1.4. OSPF Specific Link Attribute TLV - The OSPF specific link attribute TLV (Type 277) is an envelope that + 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 18: OSPF specific link attribute format + 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 278) is an envelope that + 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 19: IS-IS specific link attribute format - -3.3.1.6. Link Area TLV - - The Area TLV (Type 279) carries the Area ID which is assigned on this - link. If a link is present in more than one Area then several - occurrences of this TLV may be generated. Since only the OSPF - protocol carries the notion of link specific areas, the Area ID has a - fixed length of 4 octets. + Figure 29: IS-IS specific link attribute format - 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 ID | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +3.3.1.6. IS-IS Area Address attribute TLV - Figure 20: Link Area TLV format + 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: - +------+--------------------------------+----------+ - | Type | Description | Length | - +------+--------------------------------+----------+ - | 280 | Multi Topology | 2 | - | 281 | Node Flag Bits | 1 | - | 282 | OSPF Specific Node Properties | variable | - | 283 | IS-IS Specific Node Properties | variable | - | 284 | Node Area ID | variable | - +------+--------------------------------+----------+ - - Table 5: Node Attribute TLVs - -3.3.2.1. Multi Topology Node TLV + +------------+--------------------------------------+----------+ + | 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 | + +------------+--------------------------------------+----------+ - The Multi Topology TLV (Type 280) 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 RFC5120, - Section 7.1 [RFC5120]. 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. + Table 6: Node Attribute 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 | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - |O A R R| Multi Topology ID | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +3.3.2.1. Node Multi Topology ID - Figure 21: Multi Topology Node TLV format + 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 - The Node Flag Bits TLV (Type 281) carries a bit mask describing node - attributes. The value is a bit array of 8 flags, where each bit - represents a node capability. + The Node Flag Bits TLV (Type 280) carries a bit mask describing node + attributes. The value is a variable length bit array of flags, where + each bit represents a node capability. 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | Flags | - +-+-+-+-+-+-+-+-+ + | Flags (variable) | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - Figure 22: Node Flag Bits TLV format + Figure 30: Node Flag Bits TLV 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 6: Node Flag Bits Definitions + Table 7: Node Flag Bits Definitions 3.3.2.3. OSPF Specific Node Properties TLV - The OSPF Specific Node Properties TLV (Type 282) is an envelope that + 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 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 23: OSPF specific Node property format + Figure 31: OSPF specific Node property format 3.3.2.4. IS-IS Specific Node Properties TLV - The IS-IS Router Specific Node Properties TLV (Type 283) is an + The IS-IS Router Specific Node Properties TLV (Type 282) is an envelope that transparently carries optional node specific TLVs 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 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 node properties (variable) | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - Figure 24: IS-IS specific Node property format - -3.3.2.5. Area Node TLV - - The Area TLV (Type 284) carries the Area ID which is assigned to this - node. If a node is present in more than one Area then several - occurrences of this TLV may be generated. Since only the IS-IS - protocol carries the notion of per-node areas, the Area ID has a - variable length of 1 to 20 octets. + Figure 32: IS-IS specific Node property format - 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 ID (variable) | - | | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +3.3.2.5. ISIS Area Address TLV - Figure 25: Area Node TLV format + 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 Prefixes are learned from the IGP topology (ISIS or OSPF) with a set - of IGP attributes (such as metric, route tags, route type, etc.) that - MUST be reflected into the LINK_STATE attribute. This section - describes the different attributes related to the IPv4/IPv6 prefixes. - Prefix Attributes TLVs SHOULD be used when advertising NLRI types 3 - and 4 only. The following attributes TLVs are defined: + of IGP attributes (such as metric, route tags, etc.) that MUST be + reflected into the LINK_STATE attribute. This section describes the + different attributes related to the IPv4/IPv6 prefixes. Prefix + Attributes TLVs SHOULD be used when advertising NLRI types 3 and 4 + only. The following attributes TLVs are defined: - +------+-------------------------+--------+-----------+ - | Type | Description | Length | Reference | - +------+-------------------------+--------+-----------+ - | 285 | IGP Flags | 4 | | - | 286 | Route Tag | 4 | [RFC5130] | - | 287 | Extended Tag | 8 | [RFC5130] | - | 288 | Metric | 4 | [RFC5305] | - | 289 | OSPF Forwarding Address | 4 | [RFC2328] | - +------+-------------------------+--------+-----------+ + +-------------------------+-------------+-----------+-----------+ + | TLV/SubTLV | Description | Length | Reference | + +-------------------------+-------------+-----------+-----------+ + | 283 | IGP Flags | 4 | 284 | + | Route Tag | 4*n | [RFC5130] | 285 | + | Extended Tag | 8*n | [RFC5130] | 286 | + | Prefix Metric | 4 | [RFC5305] | 287 | + | OSPF Forwarding Address | 4 | [RFC2328] | | + +-------------------------+-------------+-----------+-----------+ - Table 7: Prefix Attribute TLVs + Table 8: Prefix Attribute TLVs 3.3.3.1. IGP Flags TLV IGP Flags TLV contains ISIS and OSPF flags and bits originally assigned to the prefix. The IGP Flags TLV is encoded 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | IGP Flags | + | IGP Flags (variable) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - Figure 26: IGP Flag TLV format + Figure 33: IGP Flag TLV format where: - Type is 285 + Type is 283 - Length is 4 + Length is variable The following bits are defined according to the table here below: +------+------------------+-----------+ | Bit | Description | Reference | +------+------------------+-----------+ | 0 | ISIS Up/Down Bit | [RFC5305] | | 1-3 | OSPF Route Type | [RFC2328] | | 4-15 | RESERVED | | +------+------------------+-----------+ - - Table 8: IGP Flag Bits Definitions + Table 9: IGP Flag Bits Definitions OSPF Route Type can be either: Intra-Area (0x1), Inter-Area (0x2), 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 Route Tag TLV carries the original IGP TAG (ISIS or OSPF) of the prefix and is encoded 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | Route Tag | + | Route Tags (one or more) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - Figure 27: IGP Route TAG TLV format + Figure 34: IGP Route TAG TLV format where: - Type is 286 + Type is 284 - Length is 4 + Length is a multiple of 4 - Route Tag contains the original tags as learned in the IGP topology. + One or more Route Tags as learned in the IGP topology. 3.3.3.3. Extended Route Tag Extended Route Tag TLV carries the ISIS Extended Route TAG of the prefix and is encoded 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | Extended Route Tag | + | Extended Route Tag (one or more) | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - Figure 28: Extended IGP Route TAG TLV format + Figure 35: Extended IGP Route TAG TLV format where: - Type is 287 + Type is 285 - Length is 8 + Length is a multiple of 8 - Extended Route Tag contains the original ISIS Extended Tag as learned - in the IGP topology. + Extended Route Tag contains one or more Extended Route Tags as + learned in the IGP topology. 3.3.3.4. Prefix Metric TLV Prefix Metric TLV carries the metric of the prefix as known in the IGP topology. The attribute is mandatory and can only appear once. 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Metric | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - Figure 29: Prefix Metric TLV Format + Figure 36: Prefix Metric TLV Format where: - Type is 288 + Type is 286 Length is 4 3.3.3.5. OSPF Forwarding Address TLV OSPF Forwarding Address TLV carries the OSPF forwarding address as known in the original OSPF advertisement. Forwarding address can be either IPv4 or IPv6. 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Forwarding Address (variable) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - Figure 30: OSPF Forwarding Address TLV Format + Figure 37: OSPF Forwarding Address TLV Format where: - Type is 289 - + Type is 287 Length is 4 for an IPv4 forwarding address an 16 for an IPv6 forwarding address 3.4. BGP Next Hop Information 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 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, 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 the BGP session. The next hop address MUST be encoded as described 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 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 one global IPv6 address followed by a link-local IPv6 address. The link-local IPv6 address should be used as described in [RFC2545]. + The BGP Next Hop attribute is used by each BGP-LS spaker to validate + the NLRI it receives. However, this specification doesn't mandate + any rule regarding the re-write of the BGP Next Hop attribute. + 3.5. Inter-AS Links 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 BGP link-state RIB an implementation must support configuration of static links. 4. Link to Path Aggregation Distribution of all links available in the global Internet is @@ -1183,93 +1507,93 @@ of nodes. The "aggregate link" represents the aggregated set of link properties between a pair of non-adjacent nodes. The actual methods to compute the path properties (of bandwidth, metric) are outside the scope of this document. The decision whether to advertise all specific links or aggregated links is an operator's policy choice. To highlight the varying levels of exposure, the following deployment examples shall be discussed. 4.1. Example: No Link Aggregation - Consider Figure 31. Both AS1 and AS2 operators want to protect their + Consider Figure 38. Both AS1 and AS2 operators want to protect their 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 path to R3. Therefore the AS2 operator exposes its topology. All 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 direct link between {R3, R4} or the {R4, R5, R3) path is used is made by the computing router. AS1 : AS2 : R1-------R3 | : | \ | : | R5 | : | / R2-------R4 : : - Figure 31: no-link-aggregation + Figure 38: no-link-aggregation 4.2. Example: ASBR to ASBR Path Aggregation The brief difference between the "no-link aggregation" example and this example is that no specific link gets exposed. Consider - Figure 32. The only link which gets advertised by AS2 is an + Figure 39. The only link which gets advertised by AS2 is an "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 hidden from the topology. AS1 : AS2 : R1-------R3 | : | | : | | : | R2-------R4 : : - Figure 32: asbr-link-aggregation + Figure 39: asbr-link-aggregation 4.3. Example: Multi-AS Path Aggregation Service providers in control of multiple ASes may even decide to not - expose their internal inter-AS links. Consider Figure 33. Rather - than exposing all specific R3 to R6 links, AS3 is modeled as a single - node which connects to the border routers of the aggregated domain. + expose their internal inter-AS links. Consider Figure 40. AS3 is + modeled as a single node which connects to the border routers of the + aggregated domain. AS1 : AS2 : AS3 : : R1-------R3----- | : : \ | : : vR0 | : : / R2-------R4----- : : : : - Figure 33: multi-as-aggregation + Figure 40: multi-as-aggregation 5. IANA Considerations This document requests a code point from the registry of Address Family Numbers. This document requests a code point from the BGP Path Attributes registry. This document requests creation of a new registry for node anchor, link descriptor and link attribute TLVs. Values 0-255 are reserved. Values 256-65535 will be used for Codepoints. The registry will be - initialized as shown in Table 2 and Table 3. Allocations within the + initialized as shown in Table 2 and Table 4. Allocations within the registry will require documentation of the proposed use of the allocated value and approval by the Designated Expert assigned by the IESG (see [RFC5226]). Note to RFC Editor: this section may be removed on publication as an RFC. 6. Manageability Considerations This section is structured as recommended in [RFC5706]. @@ -1268,30 +1592,29 @@ IESG (see [RFC5226]). Note to RFC Editor: this section may be removed on publication as an RFC. 6. Manageability Considerations This section is structured as recommended in [RFC5706]. 6.1. Operational Considerations - 6.1.1. Operations Existing BGP operation procedures apply. No new operation procedures are defined in this document. It shall be noted that the NLRI information present in this document purely carries application level data that have no immediate corresponding forwarding state impact. As such, any churn in reachability information has different impact - than regular BGP update which needs to chaange forwarding state for - an entire router. Furthermore it is anticipated that distribution of + than regular BGP update which needs to change forwarding state for an + entire router. Furthermore it is anticipated that distribution of this NLRI will be handled by dedicated route-reflectors providing a level of isolation and fault-containment between different NLRI types. 6.1.2. Installation and Initial Setup Configuration parameters defined in Section 6.2.3 SHOULD be initialized to the following default values: o The Link-State NLRI capability is turned off for all neighbors. @@ -1341,29 +1664,29 @@ An implementation SHOULD allow the operator to specify neighbors to which Link-State NLRIs will be advertised and from which Link-State NLRIs will be accepted. An implementation SHOULD allow the operator to specify the maximum rate at which Link State NLRIs will be advertised/withdrawn from neighbors An implementation SHOULD allow the operator to specify the maximum - rate at which Link State NLRIs will be accepted from neighbors - - An implementation SHOULD allow the operator to specify the maximum number of Link State NLRIs stored in router's RIB. An implementation SHOULD allow the operator to create abstracted topologies that are advertised to neighbors; Create different abstractions for different neighbors. + An implementation SHOULD allow the operator to configure a pair of + ASN and BGP identifier per flooding set the node participates in. + 6.2.4. Accounting Management Not Applicable. 6.2.5. Performance Management An implementation SHOULD provide the following statistics: o Total number of Link-State NLRI updates sent/received @@ -1372,42 +1694,110 @@ o Number of errored received Link-State NLRI updates, per neighbor o Total number of locally originated Link-State NLRIs 6.2.6. Security Management An operator SHOULD define ACLs to limit inbound updates as follows: o Drop all updates from Consumer peers -7. Security Considerations +7. TLV/SubTLV Code Points Summary + + This section contains the global table of all TLVs/SubTLVs defined in + this document. + + +------------+--------------------+---------------+-----------------+ + | TLV/SubTLV | Description | IS-IS | Value defined | + | | | TLV/Sub-TLV | in: | + +------------+--------------------+---------------+-----------------+ + | 256 | Identifier | -- | Section 3.2.1 | + | 257 | Local Node | -- | Section 3.2.2.1 | + | | Descriptors | | | + | 258 | Remote Node | -- | Section 3.2.2.2 | + | | Descriptors | | | + | 259 | Autonomous System | -- | Section 3.2.2.3 | + | 260 | BGP Identifier | -- | Section 3.2.2.3 | + | 261 | ISO Node-ID | -- | Section 3.2.2.3 | + | 262 | IPv4 Router-ID | -- | Section 3.2.2.3 | + | 263 | IPv6 Router-ID | -- | Section 3.2.2.3 | + | 264 | Link Local/Remote | 22/4 | [RFC5307]/1.1 | + | | Identifiers | | | + | 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 | + | 269 | Administrative | 22/3 | [RFC5305]/3.1 | + | | group (color) | | | + | 270 | Maximum link | 22/9 | [RFC5305]/3.3 | + | | bandwidth | | | + | 271 | Max. reservable | 22/10 | [RFC5305]/3.5 | + | | link bandwidth | | | + | 272 | Unreserved | 22/11 | [RFC5305]/3.6 | + | | bandwidth | | | + | 273 | TE Default Metric | 22/18 | [RFC5305]/3.7 | + | 274 | Link Protection | 22/20 | [RFC5307]/1.2 | + | | Type | | | + | 275 | MPLS Protocol Mask | -- | Section 3.3.1.1 | + | 276 | Metric | -- | Section 3.3.1.2 | + | 277 | Shared Risk Link | -- | Section 3.3.1.3 | + | | Group | | | + | 278 | OSPF specific link | -- | Section 3.3.1.4 | + | | attribute | | | + | 279 | IS-IS Specific | -- | Section 3.3.1.5 | + | | Link Attribute | | | + | 280 | Node Flag Bits | -- | Section 3.3.2.2 | + | 281 | OSPF Specific Node | -- | Section 3.3.2.3 | + | | Properties | | | + | 282 | IS-IS Specific | -- | Section 3.3.2.4 | + | | Node Properties | | | + | 283 | IGP Flags | -- | Section 3.3.3.1 | + | 284 | Route Tag | -- | [RFC5130] | + | 285 | Extended Tag | -- | [RFC5130] | + | 286 | Prefix Metric | -- | [RFC5305] | + | 287 | OSPF Forwarding | -- | [RFC2328] | + | | Address | | | + +------------+--------------------+---------------+-----------------+ + + Table 10: Summary Table of TLV/SubTLV Codepoints + +8. Security Considerations Procedures and protocol extensions defined in this document do not affect the BGP security model. A BGP Speaker SHOULD NOT accept updates from a Consumer peer. An operator SHOULD employ a mechanism to protect a BGP Speaker against DDOS attacks from Consumers. -8. Acknowledgements +9. Contributors - We would like to thank Nischal Sheth, Alia Atlas, Robert Varga, David - Ward, Derek Yeung, Murtuza Lightwala, John Scudder, Kaliraj - Vairavakkalai, Les Ginsberg, Liem Nguyen, Manish Bhardwaj, Mike - Shand, Peter Psenak, Rex Fernando, Richard Woundy, Saikat Ray, Steven - Luong, Tamas Mondal, Waqas Alam, and Yakov Rekhter for their - comments. + We would like to thank Robert Varga for the significant contribution + he gave to this document. -9. References +10. Acknowledgements -9.1. Normative References + We would like to thank Nischal Sheth, Alia Atlas, David Ward, Derek + Yeung, Murtuza Lightwala, John Scudder, Kaliraj Vairavakkalai, Les + Ginsberg, Liem Nguyen, Manish Bhardwaj, Mike Shand, Peter Psenak, Rex + Fernando, Richard Woundy, Steven Luong, Tamas Mondal, Waqas Alam, + Vipin Kumar, Naiming Shen and Yakov Rekhter for their comments. + +11. References + +11.1. Normative References [RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and dual environments", RFC 1195, December 1990. [RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and E. Lear, "Address Allocation for Private Internets", BCP 5, RFC 1918, February 1996. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. @@ -1426,33 +1816,27 @@ Support of Generalized Multi-Protocol Label Switching (GMPLS)", RFC 4202, October 2005. [RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway Protocol 4 (BGP-4)", RFC 4271, January 2006. [RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter, "Multiprotocol Extensions for BGP-4", RFC 4760, January 2007. - [RFC4893] Vohra, Q. and E. Chen, "BGP Support for Four-octet AS - Number Space", RFC 4893, May 2007. - [RFC4915] Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P. Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF", RFC 4915, June 2007. [RFC5036] Andersson, L., Minei, I., and B. Thomas, "LDP Specification", RFC 5036, October 2007. - [RFC5065] Traina, P., McPherson, D., and J. Scudder, "Autonomous - System Confederations for BGP", RFC 5065, August 2007. - [RFC5120] Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi Topology (MT) Routing in Intermediate System to Intermediate Systems (IS-ISs)", RFC 5120, February 2008. [RFC5130] Previdi, S., Shand, M., and C. Martin, "A Policy Control Mechanism in IS-IS Using Administrative Tags", RFC 5130, February 2008. [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 5226, @@ -1461,32 +1845,30 @@ [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic Engineering", RFC 5305, October 2008. [RFC5307] Kompella, K. and Y. Rekhter, "IS-IS Extensions in Support of Generalized Multi-Protocol Label Switching (GMPLS)", RFC 5307, October 2008. [RFC6119] Harrison, J., Berger, J., and M. Bartlett, "IPv6 Traffic Engineering in IS-IS", RFC 6119, February 2011. -9.2. Informative References + [RFC6822] Previdi, S., Ginsberg, L., Shand, M., Roy, A., and D. + Ward, "IS-IS Multi-Instance", RFC 6822, December 2012. + +11.2. Informative References [I-D.ietf-alto-protocol] Alimi, R., Penno, R., and Y. Yang, "ALTO Protocol", draft-ietf-alto-protocol-13 (work in progress), September 2012. - [I-D.ietf-isis-mi] - Previdi, S., Ginsberg, L., Shand, M., Roy, A., and D. - Ward, "IS-IS Multi-Instance", draft-ietf-isis-mi-08 (work - in progress), October 2012. - [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation Element (PCE)-Based Architecture", RFC 4655, August 2006. [RFC4970] Lindem, A., Shen, N., Vasseur, JP., Aggarwal, R., and S. Shaffer, "Extensions to OSPF for Advertising Optional Router Capabilities", RFC 4970, July 2007. [RFC5073] Vasseur, J. and J. Le Roux, "IGP Routing Protocol Extensions for Discovery of Traffic Engineering Node Capabilities", RFC 5073, December 2007. @@ -1497,20 +1879,23 @@ RFC 5152, February 2008. [RFC5693] Seedorf, J. and E. Burger, "Application-Layer Traffic Optimization (ALTO) Problem Statement", RFC 5693, October 2009. [RFC5706] Harrington, D., "Guidelines for Considering Operations and Management of New Protocols and Protocol Extensions", 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- Instance Extensions", RFC 6549, March 2012. Authors' Addresses Hannes Gredler Juniper Networks, Inc. 1194 N. Mathilda Ave. Sunnyvale, CA 94089 US