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4over6 Access

4over6 Access. For IPv4 Provisioning in IPv6 Network. 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. Introduction. Pure IPv6 network

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4over6 Access

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  1. 4over6 Access For IPv4 Provisioning in IPv6 Network 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) NO NAT44 NO NAT64 IPv4 Service IPv4 Internet IPv6 Edge Network Local IPv4 Network

  3. Use case study • 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 Servicethan using private IPv4 addresses • Summary: We need IPv4 access over IPv6 network without NAT

  4. 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 NO NAT44 NO NAT64 IPv4 Internet IPv6 Edge Network Local IPv4 Network Leverage IPv4 global address 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 • IPv4 network DHCPv4 Relay IPv6 Edge Network DHCPv4 Server Request: global IPv4 IPv4 Internet Request: global IPv4 reply: global IPv4 addr CPE TC • reply: global IPv4 addr addr mapping table Allocated v4 CPE v6 DHCPv4 over IPv6(IPv4-in-IPv6 tunnel)

  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

  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

  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_ADDR option-len: 17 octets NSP length(1 octet) IPv4-Embedded IPv6 address(16 octets)

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