1. For IPv4 Provisioning in IPv6 Network 1 Yong Cui, Jianping Wu, Peng Wu. Tsinghua Univ. (CERNET) Chris Metz. Cisco Systems Olivier Vautrin, Alain Durand. Juniper Networks Yiu L. Lee. Comcast Contact: cuiyong@tsinghua.edu.cn

2. Introduction Pure IPv6 network With the coming IPv4 address exhaustion, pure & native IPv6 network comes to reality IPv4 access is still required for users in IPv6 network Softwire IPv4-over-IPv6 Hub & Spoke Some IPv4 users need to be visited by IPv4 Internet E.g., application servers which provide IPv4 service Operators (CERNET) need to support all apps & avoid xlate (NAT44 or NAT64) IPv4 Internet IPv4 Service NO NAT44 NO NAT64 NO NAT44 NO NAT64 IPv6 Edge Network 2 Local IPv4 Network Local IPv4 Network

3. high-end clients (host/home network): Hope to own global IPv4 address to support various apps better Servers: Move existing IPv4 servers to IPv6 networks without loss of IPv4 clients, so important to support IPv4 servers in IPv6 access networks Local networks(enterprise): Need controllable access to IPv4 Internet without any NAT or address sharing Having global IPv4 addresses will be a Value-Added Service than using private IPv4 addresses Summary: We need IPv4 access over IPv6 network without NAT 3 Use case study

4. Leverage IPv4 global address General Idea of 4over6 Access Remove NAT from CGN in DS-Lite Bidirectional 4over6 tunnel For traversing IPv4 traffic over IPv6 networks Leverage existing global IPv4 addresses Assign global IPv4 addresses dynamically to local network/host Operators can leverage their existing resource of IPv4 blocks IPv4 Internet NO NAT44 NO NAT64 NO NAT44 NO NAT64 IPv6 Edge Network Local IPv4 Network Local IPv4 Network bidirectional 4over6 tunnel

5. Stateful 4over6 Access DHCPv4 server(could be TC) maintains global IPv4 addr pool CPE Relay DHCPv4 message between host & TC Encap DHCPv4 in IPv4-in-IPv6 Tunnel TC Maintains the addr mapping between allocated IPv4 & CPE IPv6 during DHCPv4 process Perform mapping table lookup of dst IPv6 addr for encapsulation Other ways to learn the v4-v6 address mapping Learn the mapping through traffic snooping Address block allocation beforehand & 4over6 routing 5 IPv4 Internet IPv6 Edge Network TC IPv4 network Request: global IPv4 CPE DHCPv4 Relay Request: global IPv4 reply: global IPv4 addr DHCPv4 Server DHCPv4 over IPv6(IPv4-in-IPv6 tunnel) addr mapping table Allocated v4 CPE v6

6. What 4over6 Access achieves? Support bidirectional communication Leverage existing global IPv4 address Support both IPv4 clients and IPv4 servers Avoid NAT44 to support all apps Avoid per-flow state maintenance Can easily combine with DS-Lite Encourage IPv4 servers move to IPv6 without loss of IPv4 users Ensure high-priority host/network to have full access to IPv4 without NAT Provide value-added service 6

7. Progress Address the 4over6 problem in access network Scenario requirement similar to DS-Lite but global IPv4 address needed Minor changes to DS-Lite Proposed the basic problem & idea during IETF 77 Presented and set up the design team in IETF 78 Periodical discussions and revisions for several rounds Revised I-D has been submitted Ready to adopt as WG item 7

8. Backup slide: Protocol Design How to inform initiators of the concentrator’s IPv6 address draft-ietf-softwire-ds-lite-tunnel-option Could be an anycast address in stateless 4over6 4over6 address ( IPv4-Embedded IPv6 address) NSP + global IPv4 addr + suffix draft-ietf-behave-address-format New DHCPv6 option (OPTION_4OVER6_ACCESS_ADDR) to require/allocate this address: Implicitly allocate IPv4 address by DHCPv6 IPv6 address assigned to the IPv6 WAN interface of CPE IPv4 address assigned to IPv4 host OPTION_4OVER6_ACCESS_ADDRoption-len: 17 octets IPv4-Embedded IPv6 address(16 octets) 8 NSP length(1 octet)