SPRING Working Group A. Alston Internet-Draft D. Henriques Intended status: Standards Track Liquid Telecom Expires: January 25, 2020 R. Bonica Juniper Networks July 24, 2019 BGP Extensions for IPv6 Compressed Routing Header (CRH) draft-alston-spring-crh-bgp-signalling-01 Abstract This document describes a new BGP extension for signalling the mapping between Segment Identifiers (SID's), as used by a SRv6+ Compressed Routing Header (CRH) and the IPv6 Addresses they represent. The extension defines both a new optional BGP attribute to signal the Maximum SID Value (MSV) and a new Sub-Address Family (SAFI) of the IPv6 Address family. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. 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 January 25, 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 Alston, et al. Expires January 25, 2020 [Page 1] Internet-Draft SRv6+ CRH BGP Signalling July 2019 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. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3 3. SID Signalling . . . . . . . . . . . . . . . . . . . . . . . 3 3.1. NLRI Format . . . . . . . . . . . . . . . . . . . . . . . 3 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 4.1. Subsequent Address Family Identifiers (SAFI) Parameters . 4 5. Security Considerations . . . . . . . . . . . . . . . . . . . 4 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 7.1. Normative References . . . . . . . . . . . . . . . . . . 4 7.2. Informative References . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 1. Overview The SRv6+ Compressed Routing Header uses an ordered sequence of segment identifiers (SID) to specify the end to end path a packet should follow through the network. This allows for much smaller header sizes than found in the SRH (Segment Routing Header), which utilizes an ordered sequence of 128 bit IPv6 address to achieve the same goal. In addition, this method prevents the overloading of the IPv6 address space. This results in the need to signal the mapping between the SIDs used in the CRH and the IPv6 addresses they represent. While such signalling can be achieved through IGP extensions [I-D.bonica-lsr-crh-isis-extensions] in a single network domain, circumstances may dictate that the SID to address mapping be signaled both to systems that do not partake in the IGP used within that network domain, and between autonomous systems. It is envisaged that such signalling will be required to signal, among other things, deep packet inspection systems and flow analysis systems that need the ability to see the full path a packet is traversing, while at the same time not necessarily partaking in the IGP which would normally be used for such signalling. This also allows signalling of SID to Address mapping in environments that do not run an IGP capable of such signalling. Alston, et al. Expires January 25, 2020 [Page 2] Internet-Draft SRv6+ CRH BGP Signalling July 2019 2. 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. SID Signalling 3.1. NLRI Format The format of the NLRI contained within the MP Reach Attribute is comprised of a 16 bit Length (2 octets) field, followed by a series of 20 octet tuples. The length of the first element of each tuple MUST be 4 octets in length and represents the 32 bit SID. The second element of the tuple is an IPv6 address and MUST be 16 octets in length. The length of the NLRI can be calculated as (20)*N where N is the number of tuples contained within the NLRI. 0 1 2 3 4 5 6 7 +-+-+-+-+-+-+-+-+ | NLRI Length | | 2 octets | +-+-+-+-+-+-+-+-+ | | | SID 1 | | (4 octets) | | | +-+-+-+-+-+-+-+-+ | | | IPv6 Address 1| | (16 octets) | | | +-+-+-+-+-+-+-+-+ | | | SID N | | (4 octets) | | | +-+-+-+-+-+-+-+-+ | | | IPv6 Address N| | (16 octets) | | | +-+-+-+-+-+-+-+-+ Alston, et al. Expires January 25, 2020 [Page 3] Internet-Draft SRv6+ CRH BGP Signalling July 2019 4. IANA Considerations This document defines new Sub-TLVs in the following existing registry: o Subsequent Address Family Identifiers (SAFI) Parameters 4.1. Subsequent Address Family Identifiers (SAFI) Parameters A new SAFI in the IANA registry for "Subsequent Address Family Identifiers (SAFI) Parameters" will be required: Codepoint Description Reference ----------------------------------------------- TBD SRv6+ CRH Signalling SAFI This document 5. Security Considerations SRv6+ CRH BGP Signalling is envisioned to be run within a trusted domain. Further aspects of security are TBD. 6. Acknowledgements The authors wish to acknowledge Ben Roberts for his support. 7. References 7.1. Normative References [I-D.bonica-6man-comp-rtg-hdr] Bonica, R., Kamite, Y., Niwa, T., Alston, A., Henriques, D., So, N., Xu, F., Chen, G., Zhu, Y., Yang, G., and Y. Zhou, "The IPv6 Compressed Routing Header (CRH)", draft- bonica-6man-comp-rtg-hdr-05 (work in progress), July 2019. [I-D.bonica-lsr-crh-isis-extensions] Kaneriya, P., Shetty, R., Hegde, S., and R. Bonica, "IS-IS Extensions To Support The IPv6 Compressed Routing Header (CRH)", draft-bonica-lsr-crh-isis-extensions-00 (work in progress), May 2019. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . Alston, et al. Expires January 25, 2020 [Page 4] Internet-Draft SRv6+ CRH BGP Signalling July 2019 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A Border Gateway Protocol 4 (BGP-4)", RFC 4271, DOI 10.17487/RFC4271, January 2006, . [RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter, "Multiprotocol Extensions for BGP-4", RFC 4760, DOI 10.17487/RFC4760, January 2007, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", STD 86, RFC 8200, DOI 10.17487/RFC8200, July 2017, . 7.2. Informative References [I-D.ietf-6man-segment-routing-header] Filsfils, C., Dukes, D., Previdi, S., Leddy, J., Matsushima, S., and d. daniel.voyer@bell.ca, "IPv6 Segment Routing Header (SRH)", draft-ietf-6man-segment-routing- header-21 (work in progress), June 2019. [I-D.ietf-spring-segment-routing-mpls] Bashandy, A., Filsfils, C., Previdi, S., Decraene, B., Litkowski, S., and R. Shakir, "Segment Routing with MPLS data plane", draft-ietf-spring-segment-routing-mpls-22 (work in progress), May 2019. [I-D.ietf-spring-srv6-network-programming] Filsfils, C., Camarillo, P., Leddy, J., daniel.voyer@bell.ca, d., Matsushima, S., and Z. Li, "SRv6 Network Programming", draft-ietf-spring-srv6-network- programming-01 (work in progress), July 2019. [RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol Label Switching Architecture", RFC 3031, DOI 10.17487/RFC3031, January 2001, . Alston, et al. Expires January 25, 2020 [Page 5] Internet-Draft SRv6+ CRH BGP Signalling July 2019 Authors' Addresses Andrew Alston Liquid Telecom Nairobi Kenya Email: Andrew.Alston@liquidtelecom.com Daniam Henriques Liquid Telecom Johannesburg South Africa Email: daniam.henriques@liquidtelecom.com Ron Bonica Juniper Networks Herndon, Virginia 20171 USA Email: rbonica@juniper.net Alston, et al. Expires January 25, 2020 [Page 6]