draft-ietf-idr-bgp-ls-segment-routing-rld-01.txt   draft-ietf-idr-bgp-ls-segment-routing-rld-02.txt 
IDR Working Group G. Van de Velde, Ed. IDR Working Group G. Van de Velde, Ed.
Internet-Draft W. Henderickx Internet-Draft W. Henderickx
Intended status: Standards Track M. Bocci Intended status: Standards Track M. Bocci
Expires: June 21, 2018 Nokia Expires: December 14, 2018 Nokia
K. Patel K. Patel
Arrcus Arrcus
December 18, 2017 June 12, 2018
Signalling ERLD using BGP-LS Signalling ERLD using BGP-LS
draft-ietf-idr-bgp-ls-segment-routing-rld-01 draft-ietf-idr-bgp-ls-segment-routing-rld-02
Abstract Abstract
This document defines the attributes to use for BGP-LS to expose ERLD This document defines the attribute encoding to use for BGP-LS to
"Entropy capable Readable Label Depth" from a node or link to a expose ERLD "Entropy capable Readable Label Depth" from a node to a
centralised controller (PCE/SDN). centralised controller (PCE/SDN).
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 [1]. document are to be interpreted as described in RFC 2119 [1].
Status of This Memo Status of This Memo
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
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 June 21, 2018. This Internet-Draft will expire on December 14, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
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publication of this document. Please review these documents publication of this document. Please review these documents
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to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used in this document . . . . . . . . . . . . . . 3 2. Conventions used in this document . . . . . . . . . . . . . . 3
2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
3. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3 3. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3
4. ERLD support by a node . . . . . . . . . . . . . . . . . . . 3 4. Origination of ERLD in BGP-LS . . . . . . . . . . . . . . . . 3
5. ERLD support by a link . . . . . . . . . . . . . . . . . . . 4 5. ERLD support by a node . . . . . . . . . . . . . . . . . . . 4
6. Security Considerations . . . . . . . . . . . . . . . . . . . 5 6. Security Considerations . . . . . . . . . . . . . . . . . . . 4
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
9.1. Normative References . . . . . . . . . . . . . . . . . . 5 9.1. Normative References . . . . . . . . . . . . . . . . . . 5
9.2. Informative References . . . . . . . . . . . . . . . . . 5 9.2. Informative References . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction 1. Introduction
When Segment Routing tunnels are computed by a centralised When Segment Routing tunnels are computed by a centralised
controller, it is beneficial that the controller knows the ERLD controller, it is beneficial that the controller knows the ERLD
(Entropy capable Readable Label Depth) of each node or link a tunnel (Entropy capable Readable Label Depth) of each node or link a tunnel
traverses. A network node signalling an ERLD MUST support the traverses. A network node signalling an ERLD MUST support the
ability to read the signalled number of labels before any action is ability to read the signalled number of labels before any action is
done upon the packet and SHOULD support entropy awareness found done upon the packet and SHOULD support entropy awareness found
within the signalled ERLD depth. within the signalled ERLD depth.
ERLD awareness of each node and link will allow a network SDN ERLD awareness of each node will allow a network SDN controller to
controller to influence the path used for each tunnel. The SDN influence the path used for each tunnel. The SDN controller may for
controller may for example only create tunnels with a label stack example only create tunnels with a label stack smaller or equal as
smaller or equal as the ERLD of each node and link on the path. This the ERLD of each node on the path. This will allow the network to
will allow the network to behave accordingly (e.g. make use of behave accordingly (e.g. make use of Entropy Labels to improve ECMP)
Entropy Labels to improve ECMP) upon the imposed Segment Routing upon the imposed Segment Routing label stack on each packet.
label stack on each packet.
This document describes how to use BGP-LS to expose the ERLD of a This document describes how to use BGP-LS to expose the ERLD of a
node. node.
2. Conventions used in this document 2. Conventions used in this document
2.1. Terminology 2.1. Terminology
BGP-LS: Distribution of Link-State and TE Information using Border BGP-LS: Distribution of Link-State and TE Information using Border
Gateway Protocol Gateway Protocol
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PCEP: Path Computation Element Protocol PCEP: Path Computation Element Protocol
SID: Segment Identifier SID: Segment Identifier
SR: Segment routing SR: Segment routing
3. Problem Statement 3. Problem Statement
In existing technology both ISIS [4] and OSPF [3] have proposed In existing technology both ISIS [4] and OSPF [3] have proposed
extensions to signal the RLD (Readable Label Depth) and ELC (Entropy extensions to signal the RLD (Readable Label Depth) and ELC (Entropy
Label Capability) of a node or link. However, if a network SDN Label Capability) of a node. However, if a network SDN controller is
controller is connected to the network through a BGP-LS session and connected to the network through a BGP-LS session and not through
not through ISIS or OSPF technology, then both RLD and ELC needs to ISIS or OSPF technology, then both RLD and ELC needs to be signalled
be signaled in BGP-LS accordingly. This document describes the using BGP-LS encoding. This document describes the extension BGP-LS
extension BGP-LS requires to transport the combination of RLD and ELC requires to transport the combined RLD and ELC into an ERLD (Entropy
into according ERLD attributes for nodes and links. capable Readable Label Depth) attribute.
A network SDN controller having awareness of the ERLD Entropy capable A network SDN controller having awareness of the ERLD can for example
Readable Label Depth can for example use it as a constraint on path use it as a constraint on path computation to make sure that high
computation so that it can make sure that high bandwidth LSPs are not bandwidth LSPs are not placed on LAG (Link Aggregation Group),
placed on LAG (Link Aggregation Group) links with smaller member containing links with smaller member bandwidth, if they know the
bandwidths if they know the Entropy Label cannot be processed by the Entropy Label cannot be processed by the node at the ingress to the
node at the ingress to the link. link.
4. ERLD support by a node 4. Origination of ERLD in BGP-LS
Both ISIS [4] and OSPF [3] have proposed extensions to signal the RLD
(Readable Label Depth) and ELC (Entropy Label Capability) for a node.
A BGP-LS router exporting the IGP LSDB, MUST NOT encode the IGP RLD
value in an BGP-LS ERLD attribute, if the associated node ELC is not
signalled.
5. ERLD support by a node
Node ERLD is encoded in a new Node Attribute TLV, as defined in Node ERLD is encoded in a new Node Attribute TLV, as defined in
RFC7752 [2]. RFC7752 [2].
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ERLD | | ERLD |
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Code-point: TBA from BGP-LS Node Descriptor, Link Descriptor, Code-point: TBA from BGP-LS Node Descriptor, Link Descriptor,
Prefix Descriptor, and Attribute TLVs registry Prefix Descriptor, and Attribute TLVs registry
Length: A 2-octet field that indicates the length of the value Length: A 2-octet field that indicates the length of the value
portion portion
ERLD: Node ERLD is a number in the range of 0-254. The value of 0 ERLD: Node ERLD is a number in the range of 0-254. The value of 0
represents lack of ability to read a label stack of any depth, any represents lack of ability to read a label stack of any depth, any
other value represents the readable label depth of the node. other value represents the readable label depth of the node.
5. ERLD support by a link
Link ERLD is encoded in a new Link Attribute TLV, as defined in
RFC7752 [2].
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ERLD |
+-+-+-+-+-+-+-+-+
Figure 2
Type : A 2-octet field specifying code-point of the new TLV type.
Code-point: TBA from BGP-LS Node Descriptor, Link Descriptor,
Prefix Descriptor, and Attribute TLVs registry
Length: A 2-octet field that indicates the length of the value
portion
ERLD: Link ERLD is a number in the range of 0-254. The value of 0
represents lack of ability to read a label stack of any depth, any
other value represents the readable label depth of the link.
6. Security Considerations 6. Security Considerations
This document does not introduce security issues beyond those This document does not introduce security issues beyond those
discussed in RFC7752 [2] discussed in RFC7752 [2]
7. Acknowledgements 7. Acknowledgements
Thanks to discussions with Acee Lindem, Jeff Tantsura, Stephane Thanks to discussions with Acee Lindem, Jeff Tantsura, Stephane
Litkowski, Bruno Decraene, Kireeti Kompella, John E. Drake and Litkowski, Bruno Decraene, Kireeti Kompella, John E. Drake and
Carlos Pignataro to bring the concept of combining ELC and RLD into a Carlos Pignataro to bring the concept of combining ELC and RLD into a
single ERLD signalled parameter more suitable for SDN controller single ERLD signalled parameter more suitable for SDN controller
based networks. based networks.
8. IANA Considerations 8. IANA Considerations
This document requests assigning 2 new code-points from the BGP-LS This document requests assigning a new code-points from the BGP-LS
Node Descriptor, Link Descriptor, Prefix Descriptor, and Attribute Node Descriptor, Link Descriptor, Prefix Descriptor, and Attribute
TLVs registry as specified in sections 4 and 5. TLVs registry as specified in section 5.
Note: placeholder IANA request
Request Node ERLD codepoint
BGP-LS TLV Code Point: TBD1
ISIS TLV 242/TBD2
Note: There is nothing in IANA from draft draft-ietf-isis-mpls-elc
Note: Draft talks only about ELC/RLD and that is mismatch with ERLD
OSPF RI TLV TBD5
OSPF ELC in Non-OSPF functionality Capability Bits (TBD6)
9. References 9. References
9.1. Normative References 9.1. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate [1] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997, Requirement Levels", BCP 14, RFC 2119, March 1997,
<http://xml.resource.org/public/rfc/html/rfc2119.html>. <http://xml.resource.org/public/rfc/html/rfc2119.html>.
[2] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and [2] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and
S. Ray, "North-Bound Distribution of Link-State and S. Ray, "North-Bound Distribution of Link-State and
Traffic Engineering (TE) Information Using BGP", RFC 7752, Traffic Engineering (TE) Information Using BGP", RFC 7752,
DOI 10.17487/RFC7752, March 2016, DOI 10.17487/RFC7752, March 2016,
<https://www.rfc-editor.org/info/rfc7752>. <https://www.rfc-editor.org/info/rfc7752>.
9.2. Informative References 9.2. Informative References
[3] Xu, X., Kini, S., Sivabalan, S., Filsfils, C., and S. [3] Xu, X., Kini, S., Sivabalan, S., Filsfils, C., and S.
Litkowski, "draft-ietf-ospf-mpls-elc", October 2016. Litkowski, "draft-ietf-ospf-mpls-elc", January 2018.
[4] Xu, X., Kini, S., Sivabalan, S., Filsfils, C., and S. [4] Xu, X., Kini, S., Sivabalan, S., Filsfils, C., and S.
Litkowski, "draft-ietf-isis-mpls-elc", October 2016. Litkowski, "draft-ietf-isis-mpls-elc", January 2018.
Authors' Addresses Authors' Addresses
Gunter Van de Velde (editor) Gunter Van de Velde (editor)
Nokia Nokia
Antwerp Antwerp
BE BE
Email: gunter.van_de_velde@nokia.com Email: gunter.van_de_velde@nokia.com
Wim Henderickx Wim Henderickx
Nokia Nokia
Belgium Belgium
Email: wim.henderickx@nokia.com Email: wim.henderickx@nokia.com
Matthew Bocci Matthew Bocci
Nokia Nokia
Shoppenhangers Road Shoppenhangers Road
Maidenhead, Berks Maidenhead, Berks
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