--- 1/draft-ietf-idr-sr-policy-path-mtu-01.txt 2020-11-01 20:13:23.259237903 -0800 +++ 2/draft-ietf-idr-sr-policy-path-mtu-02.txt 2020-11-01 20:13:23.283238511 -0800 @@ -1,23 +1,23 @@ Interdomain Routing Working Group C. Li Internet-Draft Huawei Technologies Intended status: Standards Track Y. Zhu -Expires: October 30, 2020 China Telecom +Expires: May 5, 2021 China Telecom A. Sawaf Saudi Telecom Company Z. Li Huawei Technologies - April 28, 2020 + November 1, 2020 Segment Routing Path MTU in BGP - draft-ietf-idr-sr-policy-path-mtu-01 + draft-ietf-idr-sr-policy-path-mtu-02 Abstract Segment Routing is a source routing paradigm that explicitly indicates the forwarding path for packets at the ingress node. An SR policy is a set of candidate SR paths consisting of one or more segment lists with necessary path attributes. However, the path maximum transmission unit (MTU) information for SR path is not available in the SR policy since the SR does not require signaling. This document defines extensions to BGP to distribute path MTU @@ -31,55 +31,55 @@ 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 October 30, 2020. + This Internet-Draft will expire on May 5, 2021. Copyright Notice Copyright (c) 2020 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. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 2.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 - 3. SR Policy for Path MTU . . . . . . . . . . . . . . . . . . . 3 - 3.1. Path MTU Sub-TLV . . . . . . . . . . . . . . . . . . . . 4 - 4. Operations . . . . . . . . . . . . . . . . . . . . . . . . . 5 - 5. Implementation Status . . . . . . . . . . . . . . . . . . . . 6 - 5.1. Huawei's Commercial Delivery . . . . . . . . . . . . . . 6 - 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 - 7. Security Considerations . . . . . . . . . . . . . . . . . . . 7 - 8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 7 - 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7 - 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 - 10.1. Normative References . . . . . . . . . . . . . . . . . . 7 - 10.2. Informative References . . . . . . . . . . . . . . . . . 8 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 + 2.1. Requirements Language . . . . . . . . . . . . . . . . . . 5 + 3. SR Policy for Path MTU . . . . . . . . . . . . . . . . . . . 5 + 3.1. Path MTU Sub-TLV . . . . . . . . . . . . . . . . . . . . 6 + 4. Operations . . . . . . . . . . . . . . . . . . . . . . . . . 7 + 5. Implementation Status . . . . . . . . . . . . . . . . . . . . 7 + 5.1. Huawei's Commercial Delivery . . . . . . . . . . . . . . 8 + 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 + 7. Security Considerations . . . . . . . . . . . . . . . . . . . 8 + 8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 9 + 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9 + 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 + 10.1. Normative References . . . . . . . . . . . . . . . . . . 9 + 10.2. Informative References . . . . . . . . . . . . . . . . . 10 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 1. Introduction Segment routing (SR) [RFC8402] is a source routing paradigm that explicitly indicates the forwarding path for packets at the ingress node. The ingress node steers packets into a specific path according to the Segment Routing Policy ( SR Policy) as defined in [I-D.ietf-spring-segment-routing-policy]. In order to distribute SR policies to the headend, [I-D.ietf-idr-segment-routing-te-policy] specifies a mechanism by using BGP. @@ -117,20 +117,64 @@ This document defines extensions to BGP to distribute path MTU information within SR policies. The Link MTU information can be obtained via BGP-LS [I-D.zhu-idr-bgp-ls-path-mtu] or some other means. With the Link MTU, the controller can compute the PMTU and convey the information via the BGP SR policy. 2. Terminology This memo makes use of the terms defined in [RFC8402] and [RFC3209]. + MTU: Maximum Transmission Unit, the size in bytes of the largest IP + packet, including the IP header and payload, that can be + transmitted on a link or path. Note that this could more properly + be called the IP MTU, to be consistent with how other standards + organizations use the acronym MTU. + + Link MTU: The Maximum Transmission Unit, i.e., maximum IP packet + size in bytes, that can be conveyed in one piece over a link. Be + aware that this definition is different from the definition used + by other standards organizations. + + For IETF documents, link MTU is uniformly defined as the IP MTU + over the link. This includes the IP header, but excludes link + layer headers and other framing that is not part of IP or the IP + payload. + + Be aware that other standards organizations generally define link + MTU to include the link layer headers. + + For the MPLS data plane, this size includes the IP header and data (or + other payload) and the label stack but does not include any lower-layer + headers. A link may be an interface (such as Ethernet or Packet-over- + SONET), a tunnel (such as GRE or IPsec), or an LSP. + + Path: The set of links traversed by a packet between a source node + and a destination node. + + Path MTU, or PMTU: The minimum link MTU of all the links in a path + between a source node and a destination node. + + For the MPLS data plane, it is the MTU of an LSP from a given LSR to + the egress(es), over each valid (forwarding) path. This size includes + the IP header and data (or other payload) and any part of the label + stack that was received by the ingress LSR before it placed the packet + into the LSP (this part of the label stack is considered part of the + payload for this LSP). The size does not include any lower-level + headers. + + Note that: The PMTU value may be modified by subtracting some overhead + introduced by protection mechanism, like TI-LFA. Therefore, the value + of PMTU dilivered to the ingress node MAY be smaller than the minimum + link MTU of all the links in a path between a source node and a + destination node. + 2.1. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. 3. SR Policy for Path MTU @@ -314,60 +358,60 @@ comments and help. 10. References 10.1. Normative References [I-D.ietf-idr-segment-routing-te-policy] Previdi, S., Filsfils, C., Talaulikar, K., Mattes, P., Rosen, E., Jain, D., and S. Lin, "Advertising Segment Routing Policies in BGP", draft-ietf-idr-segment-routing- - te-policy-08 (work in progress), November 2019. + te-policy-09 (work in progress), May 2020. [I-D.ietf-spring-segment-routing-policy] - Filsfils, C., Sivabalan, S., Voyer, D., Bogdanov, A., and + Filsfils, C., Talaulikar, K., Voyer, D., Bogdanov, A., and P. Mattes, "Segment Routing Policy Architecture", draft- - ietf-spring-segment-routing-policy-06 (work in progress), - December 2019. + ietf-spring-segment-routing-policy-08 (work in progress), + July 2020. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., Decraene, B., Litkowski, S., and R. Shakir, "Segment Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, July 2018, . 10.2. Informative References [I-D.ietf-spring-mpls-path-segment] Cheng, W., Li, H., Chen, M., Gandhi, R., and R. Zigler, "Path Segment in MPLS Based Segment Routing Network", - draft-ietf-spring-mpls-path-segment-02 (work in progress), - February 2020. + draft-ietf-spring-mpls-path-segment-03 (work in progress), + September 2020. [I-D.li-spring-srv6-path-segment] Li, C., Cheng, W., Chen, M., Dhody, D., and R. Gandhi, "Path Segment for SRv6 (Segment Routing in IPv6)", draft- - li-spring-srv6-path-segment-05 (work in progress), March - 2020. + li-spring-srv6-path-segment-06 (work in progress), + September 2020. [I-D.zhu-idr-bgp-ls-path-mtu] - Zhu, Y., Hu, Z., Yan, G., and J. Yao, "BGP-LS Extensions - for Advertising Path MTU", draft-zhu-idr-bgp-ls-path- - mtu-02 (work in progress), January 2020. + Zhu, Y., Hu, Z., Peng, S., and R. Mwehair, "BGP-LS + Extensions for Advertising Path MTU", draft-zhu-idr-bgp- + ls-path-mtu-04 (work in progress), August 2020. [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001, . [RFC7942] Sheffer, Y. and A. Farrel, "Improving Awareness of Running Code: The Implementation Status Section", BCP 205, RFC 7942, DOI 10.17487/RFC7942, July 2016, .