--- 1/draft-ietf-idr-bgp-ls-segment-routing-rld-04.txt 2019-08-20 04:14:01.950426673 -0700 +++ 2/draft-ietf-idr-bgp-ls-segment-routing-rld-05.txt 2019-08-20 04:14:02.030428691 -0700 @@ -1,21 +1,21 @@ IDR Working Group G. Van de Velde, Ed. Internet-Draft W. Henderickx Intended status: Standards Track M. Bocci -Expires: December 20, 2019 Nokia +Expires: February 21, 2020 Nokia K. Patel Arrcus - June 18, 2019 + August 20, 2019 Signalling ERLD using BGP-LS - draft-ietf-idr-bgp-ls-segment-routing-rld-04 + draft-ietf-idr-bgp-ls-segment-routing-rld-05 Abstract This document defines the attribute encoding to use for BGP-LS to expose ERLD "Entropy capable Readable Label Depth" from a node to a centralised controller (PCE/SDN). Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", @@ -30,58 +30,57 @@ 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 https://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 December 20, 2019. + This Internet-Draft will expire on February 21, 2020. Copyright Notice Copyright (c) 2019 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 (https://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 described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 - 2. Conventions used in this document . . . . . . . . . . . . . . 3 + 2. Conventions used in this document . . . . . . . . . . . . . . 2 2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 3. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3 - 4. Origination of ERLD in BGP-LS . . . . . . . . . . . . . . . . 3 - 5. ERLD support by a node . . . . . . . . . . . . . . . . . . . 4 - 6. Security Considerations . . . . . . . . . . . . . . . . . . . 4 - 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 - 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 - 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 - 9.1. Normative References . . . . . . . . . . . . . . . . . . 5 - 9.2. Informative References . . . . . . . . . . . . . . . . . 5 + 4. Advertising of ERLD in BGP-LS . . . . . . . . . . . . . . . . 3 + 5. Security Considerations . . . . . . . . . . . . . . . . . . . 4 + 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 + 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 + 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 + 8.1. Normative References . . . . . . . . . . . . . . . . . . 4 + 8.2. Informative References . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 1. Introduction When Segment Routing tunnels are computed by a centralised controller, it is beneficial that the controller knows the ERLD - (Entropy capable Readable Label Depth) of each node or link a tunnel + (Entropy Readable Label Depth) of each node or link a tunnel traverses. A network node signalling an ERLD MUST support the ability to read the signalled number of labels before any action is done upon the packet and SHOULD support entropy awareness found within the signalled ERLD depth. ERLD awareness of each node will allow a network SDN controller to influence the path used for each tunnel. The SDN controller may for example only create tunnels with a label stack smaller or equal as the ERLD of each node on the path. This will allow the network to behave accordingly (e.g. make use of Entropy Labels to improve ECMP) @@ -84,160 +83,151 @@ influence the path used for each tunnel. The SDN controller may for example only create tunnels with a label stack smaller or equal as the ERLD of each node on the path. This will allow the network to behave accordingly (e.g. make use of Entropy Labels to improve ECMP) upon the imposed Segment Routing label stack on each packet. This document describes how to use BGP-LS to expose the ERLD of a node. 2. Conventions used in this document - 2.1. Terminology BGP-LS: Distribution of Link-State and TE Information using Border Gateway Protocol ERLD: Entropy capable Readable Label Depth - PCC: Path Computation Client - - PCE: Path Computation Element + ELC: Entropy Label Capability - PCEP: Path Computation Element Protocol + MSD: Maximum SID Depth SID: Segment Identifier - SR: Segment routing - 3. Problem Statement - In existing technology both ISIS [4] and OSPF [3] have proposed - extensions to signal the RLD (Readable Label Depth) and ELC (Entropy - Label Capability) of a node. However, if a network SDN controller is - connected to the network through a BGP-LS session and not through - ISIS or OSPF technology, then both RLD and ELC needs to be signalled - using BGP-LS encoding. This document describes the extension BGP-LS - requires to transport the combined RLD and ELC into an ERLD (Entropy - capable Readable Label Depth) attribute. + For Segment Routing technology both ISIS [7] and OSPF [6] have + proposed extensions to signal the ERLD (Entropy Readable Label Depth) + and ELC (Entropy Label Capability) of a node. However, if a network + SDN controller is connected to the network through a BGP-LS session + and not through either ISIS or OSPF technology, then both ERLD and + ELC needs to be signalled using BGP-LS encoding. This document + describes the extension BGP-LS requires to signal ERLD. A network SDN controller having awareness of the ERLD can for example use it as a constraint on path computation to make sure that high bandwidth LSPs are not placed on LAG (Link Aggregation Group), containing links with smaller member bandwidth, if they know the - Entropy Label cannot be processed by the node at the ingress to the + entropy label cannot be processed by the node at the ingress to the link. -4. Origination of ERLD in BGP-LS +4. Advertising 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. + Both ISIS [7] and OSPF [6] have proposed extensions to signal the + ERLD (Entropy Readable Label Depth) and ELC (Entropy Label + Capability) using new MSD-type of the Node MSD sub-Type TLV RFC8491 + [4] or RFC8476 [3]. -5. ERLD support by a node + This document defines a new node BGP MSD sub-type TLV from draft- + ietf-idr-bgp-ls-segment-routing-msd [5] to signal the ERLD. - Node ERLD is encoded in a new Node Attribute TLV, as defined in - RFC7752 [2]. + A BGP-LS router exporting the IGP LSDB, MUST NOT encode the IGP ERLD + value in an BGP-LS ERLD attribute, if the associated ELC is not + signalled. 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 | - +-+-+-+-+-+-+-+-+ + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | MSD-Type=TBD | ERLD-Value | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1 - 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 + The BGP-LS ERLD is encoded as a node MSD sub-type defined in the IANA + registry titled "IGP MSD-Types" under the "Interior Gateway Protocol + (IGP) Parameters" registry created by RFC8491 [4]. - 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 - other value represents the readable label depth of the node. + The ERLD-Value field in the range between 0 to 255 is set to the BGP- + LS imported IGP ERLD. 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 node. -6. Security Considerations +5. Security Considerations This document does not introduce security issues beyond those discussed in RFC7752 [2] -7. Acknowledgements +6. Acknowledgements Thanks to discussions with Acee Lindem, Jeff Tantsura, Stephane Litkowski, Bruno Decraene, Kireeti Kompella, John E. Drake and Carlos Pignataro to bring the concept of combining ELC and RLD into a single ERLD signalled parameter more suitable for SDN controller based networks. -8. IANA Considerations +7. IANA Considerations - This document requests assigning a new code-points from the BGP-LS - Node Descriptor, Link Descriptor, Prefix Descriptor, and Attribute - TLVs registry as specified in section 5. + This document requests assigning new BGP MSD sub-TLV code-points as + described in section 4. 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 +8. References -9.1. Normative References +8.1. Normative References [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997, . [2] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and S. Ray, "North-Bound Distribution of Link-State and Traffic Engineering (TE) Information Using BGP", RFC 7752, DOI 10.17487/RFC7752, March 2016, . -9.2. Informative References + [3] Tantsura, J., Chunduri, U., Aldrin, S., and P. Psenak, + "Signaling Maximum SID Depth (MSD) Using OSPF", RFC 8476, + DOI 10.17487/RFC8476, December 2018, + . - [3] Xu, X., Kini, S., Sivabalan, S., Filsfils, C., and S. - Litkowski, "draft-ietf-ospf-mpls-elc", January 2018. + [4] Tantsura, J., Chunduri, U., Aldrin, S., and L. Ginsberg, + "Signaling Maximum SID Depth (MSD) Using IS-IS", RFC 8491, + DOI 10.17487/RFC8491, November 2018, + . - [4] Xu, X., Kini, S., Sivabalan, S., Filsfils, C., and S. - Litkowski, "draft-ietf-isis-mpls-elc", January 2018. + [5] Tantsura, J., Chunduri, U., Talaulikar, K., Mirsky, G., + and N. Triantafillis, "draft-ietf-idr-bgp-ls-segment- + routing-msd", June 2019. + +8.2. Informative References + + [6] Xu, X., Kini, S., Sivabalan, S., Filsfils, C., and S. + Litkowski, "draft-ietf-ospf-mpls-elc", May 2019. + + [7] Xu, X., Kini, S., Sivabalan, S., Filsfils, C., and S. + Litkowski, "draft-ietf-isis-mpls-elc", May 2019. Authors' Addresses Gunter Van de Velde (editor) Nokia Antwerp BE Email: gunter.van_de_velde@nokia.com + Wim Henderickx Nokia Belgium Email: wim.henderickx@nokia.com - Matthew Bocci Nokia Shoppenhangers Road Maidenhead, Berks UK Email: matthew.bocci@nokia.com Keyur Patel Arrcus