Extension Header Use Cases
draft-mcbride-v6ops-eh-use-cases-01

Internet Engineering Task Force                               M. McBride
Internet-Draft                                                 Futurewei
Intended status: Informational                                 N. Elkins
Expires: 29 August 2024                             Inside Products, Inc
                                                             N. Buraglio
                                                        Forwarding Plane
                                                                 X. Geng
                                                     Huawei Technologies
                                                            M. Ackermann
                                                           BCBS Michigan
                                                        26 February 2024

                       Extension Header Use Cases
                  draft-mcbride-v6ops-eh-use-cases-01

Abstract

   This document outlines IPv6 extension header use cases including
   those intended to be deployed in limited domains and those intended
   for the global Internet.  We specify use cases are deployed today and
   those which may be of use in the future.  The hope is that through
   understanding these various extension header use cases, we can then
   better understand how best to improve upon extension header
   deployments including any limits on their use.

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
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   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 29 August 2024.

Copyright Notice

   Copyright (c) 2024 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   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 Revised BSD License text as
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   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Glossary  . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Standards Based Extension Headers . . . . . . . . . . . . . .   3
     3.1.  Segment Routing Header (SRH)  . . . . . . . . . . . . . .   4
     3.2.  Performance and Diagnostic Metrics (PDM)  . . . . . . . .   4
     3.3.  Mobility Header . . . . . . . . . . . . . . . . . . . . .   4
     3.4.  Alternate-Marking Method  . . . . . . . . . . . . . . . .   5
     3.5.  MLD Messages  . . . . . . . . . . . . . . . . . . . . . .   5
   4.  Proposed Extension Headers  . . . . . . . . . . . . . . . . .   5
     4.1.  Application Aware Networking  . . . . . . . . . . . . . .   5
     4.2.  Integrated Multicast Bitstring  . . . . . . . . . . . . .   5
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   6.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .   6
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   8.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   6
   9.  Change Log  . . . . . . . . . . . . . . . . . . . . . . . . .   7
   10. Open Issues . . . . . . . . . . . . . . . . . . . . . . . . .   7
   11. Normative References  . . . . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  11

1.  Introduction

   Extension headers have been specified since original 1995 IPv6
   Specification [RFC2460] and maintained in the more recently updated
   [RFC8200].  In the nearly 30 years since extension headers were
   specified, there have been many documents which have specified how to
   limit, block and deprecate their use.  What we haven't had is a
   document to show how extension headers are being deployed nor how
   related innovations are being proposed.  This document outlines IPv6
   extension header use cases including those intended to be deployed in
   limited domains and those deployed across the Internet.  By
   understanding these various use cases we can better understand how
   best to improve upon, and perhaps limit, extension header deployment.

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2.  Glossary

   EH: IPv6 Extension Header

   Hop-by-Hop Optioners Header: Used to carry optional information
   intended for every node along the path.

   Routing Header: Used to list one or more nodes to be visited on the
   way to a packet's destination.

   Fragment Header: Used to send a packet larger than would fit in the
   path MTU to its destination.

   Encapsulating Security Payload: The Encapsulating Security Payload
   (ESP) extension header provides confidentiality, integrity, and
   authentication for IPv6 packets.

   Authentication Header: The IPv6 Authentication Header (AH) extension
   provides data integrity, authentication, and anti-replay protection
   for IPv6 packets.

   Destination Options Header: Used to carry optional information for
   destination nodes.

   Mobility Header: The Mobility Header enables mobility support for
   network nodes in IPv6 networks.

   Host Identity Protocol: The Host Identity Protocol (HIP) provides a
   cryptographic identity-based solution for secure communication and
   mobility management in IPv6 networks.

   Shim6 Protocol: The Shim6 IPv6 extension header enables multihoming
   by providing source and destination address selection for efficient
   routing.

   Single Administrative Domain: The EH is limited to one administrative
   domain.

   Limited Domain: The EH is limited to a group of administrative
   domains.

   Unlimited Domain: The EH is not limited to any group of domains.

3.  Standards Based Extension Headers

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3.1.  Segment Routing Header (SRH)

   Segment Routing (SR) can be applied to the IPv6 data plane using a
   routing header called the Segment Routing Header (SRH).  [RFC8402]
   Defines SRv6 with SRH and SRv6 SID's.  [RFC8754] specifies the
   encoding of IPv6 segments in an SRH.  SRv6 uses this IPv6 Routing
   Extension Header to forward IPv6 packets using the source routing
   model.  The SRH isn't examined by intermediate nodes along the path
   to the destination unless it implements the hop-by-hop options
   header.  According to [I-D.matsushima-spring-srv6-deployment-status],
   there have been over 10 announced deployments of an SRH based data
   plane and over 20 additional deployments without public
   announcements.  There are many large scale SRv6 commerical
   deployments, many SRv6 implementations and many SRv6 open source
   platforms.  Segment Routing is intended to be used in a limited
   domain

3.2.  Performance and Diagnostic Metrics (PDM)

   RFC 8250 specifies the Performance and Diagnostic Metrics (PDM)
   Destination Options header, which is used to measure the performance
   of IPv6 networks.  The PDM header contains sequence numbers and
   timing information that can be used to calculate metrics such as
   round-trip delay and server delay.

   The PDM header is embedded in each packet, and the information it
   contains is combined with the 5-tuple (source IP address, source
   port, destination IP address, destination port, and upper-layer
   protocol) to calculate the metrics.  The PDM header also includes
   fields for storing time scaling factors, which can be used to adjust
   the measurements for different network conditions.

   The PDM header can be used to assess performance problems in real
   time or after the fact.  The measurements can be used to troubleshoot
   network problems, identify bottlenecks, and optimize network
   performance.

3.3.  Mobility Header

   [RFC6275] specifies Mobile IPv6, a protocol that allows nodes to
   remain reachable while moving around in the IPv6 Internet.The
   Mobility Header is an extension header used by mobile nodes,
   correspondent nodes, and home agents in all messaging related to the
   creation and management of mobile bindings.  The Mobility Header is
   identified by a Next Header value of 135.

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3.4.  Alternate-Marking Method

   [RFC9343] describes how the Alternate-Marking Method can be used as a
   passive performance measurement tool in an IPv6 domain.  It defines
   an Extension Header Option to encode Alternate-Marking information in
   both the Hop-by-Hop Options Header and Destination Options Header.

3.5.  MLD Messages

   Multicast Listener Discovery (MLD) is used today by IPv6 routers for
   discovering multicast listeners on a directly attached link, much
   like Internet Group Management Protocol (IGMP) is used in IPv4.  MLD
   uses ICMPv6 (IP Protocol 58) message types, rather than IGMP (IP
   Protocol 2) message types.  MLD messages are identified in IPv6
   packets by a preceding Next Header value of 58.  MLD messages are
   sent with an IPv6 Router Alert option in a Hop-by-Hop Options header
   as defined in [RFC2710].

4.  Proposed Extension Headers

4.1.  Application Aware Networking

   Application-aware IPv6 Networking (APN6) makes use of IPv6
   encapsulation to convey the APN Attribute along with data packets and
   make the network aware of data flow requirements at different
   granularity levels.  The APN attribute can be encapsulated in the APN
   header.  As network technologies evolve including deployments of
   IPv6, SRv6, Segment Routing over MPLS dataplane, the programmability
   provided by IPv6 and Segment Routing can be augmented by conveying
   application related information into the network satisfying the fine-
   granularity requirements.  APN documents outline various use cases
   that could benefit from an Application-aware Networking (APN)
   framework

4.2.  Integrated Multicast Bitstring

   There's a potential deployment of using a bitstring (such as used in
   BIER) as part of the IPv6 data plane using an EH.

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            |<<-----(BIER-based multicast overlay)----->>|
            |                                            |
            |<----------(L3 BIER(P2MP) tunnel)---------->|
            |                                            |
            |  SEP                 SEP       SEP    SEP  |
            |    +******************+          +****+    |
            |   /                    \        /      \   |
        +------+       +-------+       +-----+        +------+
        | BFIR |-------|Non-BFR|-------| BFR |--------| BFER |
        +------+       +-------+       +-----+        +------+

        ------- L2 link

        ******* IPv6(P2P) segment (SEP = Segment EndPoint)

        <-----> BIER(P2MP) tunnel

   In this deployment, BIER works as part of the IPv6 data plane.  The
   BFIR and BFERs work as IPv6 (P2MP) tunnel endpoints, and BFRs work as
   IPv6 segment endpoints.  The BIER header is processed on each segment
   endpoint and there is no decapsulation, or re-encapsulation, on the
   segment endpoints.

   This deployment typically needs an IPv6 extension header to carry the
   BIER header and processing of the BIER header (e.g., the bitstring)
   will be implemented as part of the IPv6 extension header processing.
   The IPv6 source address is the BIER packet source-origin identifier,
   and is unchanged through the BIER domain from BFIR to BFERs.

5.  Security Considerations

   None.

6.  Privacy Considerations

   None.

7.  IANA Considerations

   None.

8.  Contributors

   Thanks to Dr. Tommaso Pecorella and Dhruv Dhody for their comments.

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9.  Change Log

   Note to RFC Editor: if this document does not obsolete an existing
   RFC, please remove this appendix before publication as an RFC

10.  Open Issues

   Note to RFC Editor: please remove this appendix before publication as
   an RFC

11.  Normative References

   [I-D.matsushima-spring-srv6-deployment-status]
              Matsushima, S., Filsfils, C., Ali, Z., Li, Z., Rajaraman,
              K., and A. Dhamija, "SRv6 Implementation and Deployment
              Status", Work in Progress, Internet-Draft, draft-
              matsushima-spring-srv6-deployment-status-15, 5 April 2022,
              <https://datatracker.ietf.org/doc/html/draft-matsushima-
              spring-srv6-deployment-status-15>.

   [RFC1421]  Linn, J., "Privacy Enhancement for Internet Electronic
              Mail: Part I: Message Encryption and Authentication
              Procedures", RFC 1421, DOI 10.17487/RFC1421, February
              1993, <https://www.rfc-editor.org/info/rfc1421>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC2236]  Fenner, W., "Internet Group Management Protocol, Version
              2", RFC 2236, DOI 10.17487/RFC2236, November 1997,
              <https://www.rfc-editor.org/info/rfc2236>.

   [RFC2460]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
              (IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460,
              December 1998, <https://www.rfc-editor.org/info/rfc2460>.

   [RFC2473]  Conta, A. and S. Deering, "Generic Packet Tunneling in
              IPv6 Specification", RFC 2473, DOI 10.17487/RFC2473,
              December 1998, <https://www.rfc-editor.org/info/rfc2473>.

   [RFC2675]  Borman, D., Deering, S., and R. Hinden, "IPv6 Jumbograms",
              RFC 2675, DOI 10.17487/RFC2675, August 1999,
              <https://www.rfc-editor.org/info/rfc2675>.

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   [RFC2710]  Deering, S., Fenner, W., and B. Haberman, "Multicast
              Listener Discovery (MLD) for IPv6", RFC 2710,
              DOI 10.17487/RFC2710, October 1999,
              <https://www.rfc-editor.org/info/rfc2710>.

   [RFC2711]  Partridge, C. and A. Jackson, "IPv6 Router Alert Option",
              RFC 2711, DOI 10.17487/RFC2711, October 1999,
              <https://www.rfc-editor.org/info/rfc2711>.

   [RFC2780]  Bradner, S. and V. Paxson, "IANA Allocation Guidelines For
              Values In the Internet Protocol and Related Headers",
              BCP 37, RFC 2780, DOI 10.17487/RFC2780, March 2000,
              <https://www.rfc-editor.org/info/rfc2780>.

   [RFC2858]  Bates, T., Rekhter, Y., Chandra, R., and D. Katz,
              "Multiprotocol Extensions for BGP-4", RFC 2858,
              DOI 10.17487/RFC2858, June 2000,
              <https://www.rfc-editor.org/info/rfc2858>.

   [RFC3692]  Narten, T., "Assigning Experimental and Testing Numbers
              Considered Useful", BCP 82, RFC 3692,
              DOI 10.17487/RFC3692, January 2004,
              <https://www.rfc-editor.org/info/rfc3692>.

   [RFC3810]  Vida, R., Ed. and L. Costa, Ed., "Multicast Listener
              Discovery Version 2 (MLDv2) for IPv6", RFC 3810,
              DOI 10.17487/RFC3810, June 2004,
              <https://www.rfc-editor.org/info/rfc3810>.

   [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,
              <https://www.rfc-editor.org/info/rfc4271>.

   [RFC4302]  Kent, S., "IP Authentication Header", RFC 4302,
              DOI 10.17487/RFC4302, December 2005,
              <https://www.rfc-editor.org/info/rfc4302>.

   [RFC4303]  Kent, S., "IP Encapsulating Security Payload (ESP)",
              RFC 4303, DOI 10.17487/RFC4303, December 2005,
              <https://www.rfc-editor.org/info/rfc4303>.

   [RFC4607]  Holbrook, H. and B. Cain, "Source-Specific Multicast for
              IP", RFC 4607, DOI 10.17487/RFC4607, August 2006,
              <https://www.rfc-editor.org/info/rfc4607>.

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   [RFC4727]  Fenner, B., "Experimental Values In IPv4, IPv6, ICMPv4,
              ICMPv6, UDP, and TCP Headers", RFC 4727,
              DOI 10.17487/RFC4727, November 2006,
              <https://www.rfc-editor.org/info/rfc4727>.

   [RFC4782]  Floyd, S., Allman, M., Jain, A., and P. Sarolahti, "Quick-
              Start for TCP and IP", RFC 4782, DOI 10.17487/RFC4782,
              January 2007, <https://www.rfc-editor.org/info/rfc4782>.

   [RFC5095]  Abley, J., Savola, P., and G. Neville-Neil, "Deprecation
              of Type 0 Routing Headers in IPv6", RFC 5095,
              DOI 10.17487/RFC5095, December 2007,
              <https://www.rfc-editor.org/info/rfc5095>.

   [RFC5533]  Nordmark, E. and M. Bagnulo, "Shim6: Level 3 Multihoming
              Shim Protocol for IPv6", RFC 5533, DOI 10.17487/RFC5533,
              June 2009, <https://www.rfc-editor.org/info/rfc5533>.

   [RFC5570]  StJohns, M., Atkinson, R., and G. Thomas, "Common
              Architecture Label IPv6 Security Option (CALIPSO)",
              RFC 5570, DOI 10.17487/RFC5570, July 2009,
              <https://www.rfc-editor.org/info/rfc5570>.

   [RFC6275]  Perkins, C., Ed., Johnson, D., and J. Arkko, "Mobility
              Support in IPv6", RFC 6275, DOI 10.17487/RFC6275, July
              2011, <https://www.rfc-editor.org/info/rfc6275>.

   [RFC6554]  Hui, J., Vasseur, JP., Culler, D., and V. Manral, "An IPv6
              Routing Header for Source Routes with the Routing Protocol
              for Low-Power and Lossy Networks (RPL)", RFC 6554,
              DOI 10.17487/RFC6554, March 2012,
              <https://www.rfc-editor.org/info/rfc6554>.

   [RFC6744]  Atkinson, RJ. and SN. Bhatti, "IPv6 Nonce Destination
              Option for the Identifier-Locator Network Protocol for
              IPv6 (ILNPv6)", RFC 6744, DOI 10.17487/RFC6744, November
              2012, <https://www.rfc-editor.org/info/rfc6744>.

   [RFC6788]  Krishnan, S., Kavanagh, A., Varga, B., Ooghe, S., and E.
              Nordmark, "The Line-Identification Option", RFC 6788,
              DOI 10.17487/RFC6788, November 2012,
              <https://www.rfc-editor.org/info/rfc6788>.

   [RFC6971]  Herberg, U., Ed., Cardenas, A., Iwao, T., Dow, M., and S.
              Cespedes, "Depth-First Forwarding (DFF) in Unreliable
              Networks", RFC 6971, DOI 10.17487/RFC6971, June 2013,
              <https://www.rfc-editor.org/info/rfc6971>.

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   [RFC7401]  Moskowitz, R., Ed., Heer, T., Jokela, P., and T.
              Henderson, "Host Identity Protocol Version 2 (HIPv2)",
              RFC 7401, DOI 10.17487/RFC7401, April 2015,
              <https://www.rfc-editor.org/info/rfc7401>.

   [RFC8200]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
              (IPv6) Specification", STD 86, RFC 8200,
              DOI 10.17487/RFC8200, July 2017,
              <https://www.rfc-editor.org/info/rfc8200>.

   [RFC8250]  Elkins, N., Hamilton, R., and M. Ackermann, "IPv6
              Performance and Diagnostic Metrics (PDM) Destination
              Option", RFC 8250, DOI 10.17487/RFC8250, September 2017,
              <https://www.rfc-editor.org/info/rfc8250>.

   [RFC8279]  Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A.,
              Przygienda, T., and S. Aldrin, "Multicast Using Bit Index
              Explicit Replication (BIER)", RFC 8279,
              DOI 10.17487/RFC8279, November 2017,
              <https://www.rfc-editor.org/info/rfc8279>.

   [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, <https://www.rfc-editor.org/info/rfc8402>.

   [RFC8754]  Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J.,
              Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header
              (SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020,
              <https://www.rfc-editor.org/info/rfc8754>.

   [RFC9008]  Robles, M.I., Richardson, M., and P. Thubert, "Using RPI
              Option Type, Routing Header for Source Routes, and IPv6-
              in-IPv6 Encapsulation in the RPL Data Plane", RFC 9008,
              DOI 10.17487/RFC9008, April 2021,
              <https://www.rfc-editor.org/info/rfc9008>.

   [RFC9180]  Barnes, R., Bhargavan, K., Lipp, B., and C. Wood, "Hybrid
              Public Key Encryption", RFC 9180, DOI 10.17487/RFC9180,
              February 2022, <https://www.rfc-editor.org/info/rfc9180>.

   [RFC9268]  Hinden, R. and G. Fairhurst, "IPv6 Minimum Path MTU Hop-
              by-Hop Option", RFC 9268, DOI 10.17487/RFC9268, August
              2022, <https://www.rfc-editor.org/info/rfc9268>.

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   [RFC9343]  Fioccola, G., Zhou, T., Cociglio, M., Qin, F., and R.
              Pang, "IPv6 Application of the Alternate-Marking Method",
              RFC 9343, DOI 10.17487/RFC9343, December 2022,
              <https://www.rfc-editor.org/info/rfc9343>.

Authors' Addresses

   Mike McBride
   Futurewei
   Email: michael.mcbride@futurewei.com

   Nalini Elkins
   Inside Products, Inc
   Email: nalini.elkins@insidethestack.com

   Nick Buraglio
   Forwarding Plane
   Email: buraglio@forwardingplane.net

   Xuesong Geng
   Huawei Technologies
   Email: gengxuesong@huawei.com

   Michael Ackermann
   BCBS Michigan
   Email: mackermann@bcbsm.com

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