Dean Cheng (chengd@huawei) Mohamed Boucadair (mohamed.boucadair@orange-ftgroup)

1. Dean Cheng (chengd@huawei.com) Mohamed Boucadair (mohamed.boucadair@orange-ftgroup.com) 79th IETF Beijing Routing IPv4-Embedded IPv6 Packets draft-cheng-ospf-ipv4-embedded-ipv6-routing-01

2. Some Terminologies • IPv4-Embedded IPv6 address • Denotes an IPv6 address which contains an embedded 32-bit IPv4 address constructed according to the rules defined in: draft-ietf-behave-address-format-10 • IPv4-Embedded IPv6 packets • IPv6 packets with destination addresses as IPv4-Embedded IPv6 addresses • AFBR • Address Family Border Router (RFC5565) • Refers to a border router which is located at the boundary of an IPv6-only network and an IPv4-only network

3. IPv6 IPv6 IPv6 IPv4 The Problem AFBR ? ? IPv6 backbone ? AFBR ASBR AFBR IPv4 IPv4 ASBR

4. IPv6 IPv6 IPv6 AFBR IPv6 backbone IPv4 IPv4 AFBR AFBR IPv4 ASBR • AFTRs exchange IPv4 reachability using BGP-MP • Tunnels established between AFTRs full-mesh • IPv4 packets transported in tunnels Softwire Mesh (RFC5565) Approach ASBR

5. IPv6 IPv6 IPv6 AFBR IPv6 backbone IPv4 IPv4 AFBR AFBR IPv4 ASBR • AFBRs advertise IPv4-Embedded IPv6 addresses into the partial IPv6 backbone • A separate routing table for routing IPv4-Embedded IPv6 packets. OSPFv3 MT/MI Approach ASBR

6. CPE CPE CPE CPE CPE CPE CPE AFTR AFTR AFTR ICXF ICXF ICXF Scenarios where OSPFv3 approach useful • Running BGP not feasible on some AFTRs. • Tunnel based forwarding not feasible IPv6 DS-Lite IPv4 IPv6 Network IPv4 IPv4 Dual-Stack IPv6 http://tools.ietf.org/html/draft-boucadair-dslite-interco-v4v6-04

7. Mechanisms for separate routing table • Use OSPFv3 multi-instance mechanism • Reference: RFC5838 • Instantiate a separate instance for IPv4-Embedded unicast IPv6 routing • Use OSPFv3 multi-topology mechanism • Reference: http://tools.ietf.org/html/draft-ietf-ospf-mt-ospfv3-03.txt • Configure interfaces for IPv4-Embedded unicast IPv6 routing

8. Advertising IPv4-Embedded IPv6 Routes • IPv4-Embedded IPv6 addresses would be advertised by AFBR into IPv6 network as AS External LSA per OSPFv3(RFC5340) • A single OSPFv3 AS External LSA carries one or more IPv4-Embedded IPv6 addresses and prefixes • By default, the metric is type-1 metric • Added to the intra-AS path for OSPFv3 routes calculation • May also be set to type-2 metric (by provisioning at AFBR) • External metric may be exact the same unit as in IPv4 network

9. Forwarding IPv4-Embedded IPv6 Packets • Arriving packets with IPv4-Embedded IPv6 addresses are forwarded along on IPv4-Embedded IPv6 topology. • Packet header translation • According to http://tools.ietf.org/html/draft-ietf-behave-v6v4-xlate-23 • Address translation • According to draft-ietf-behave-address-format-10 • IPv6 prefix • Well known IPv6 prefix 64::FF9B::/96, or • ISP-specific IPv6 prefix • MTU handling • Recommendation – AFTR to run PMTU (RFC1981.txt)

10. An issue for discussion • In Section 2.6 of RFC5838 • IPv4 address is located in the first 32-bit of the Forwarding Address field in AS-external LSA, with the remaining bits set to zero. • In this draft • IPv4-Embedded IPv6 address encoded according to: draft-ietf-behave-address-format-10 • Question for the WG: • How to resolve this issue?

11. Next Step … • Authors would like to solicit comments with discussion on mailing list at this time • If there is enough interest, we’ll propose to move this I-D as a working group document