1. For IPv6 host connecting IPv4 Internet 1 Yong Cui, Jianping Wu Tsinghua Univ. (CERNET) Contact: cuiyong@tsinghua.edu.cn

2. Outline Introduction Elements in host 4over6 Stateless approach Combination with Dual-Stack Lite Stateful approach Next steps 2

3. Introduction Pure IPv6 network With the coming IPv4 address exhaustion, pure & native IPv6 network comes to reality IPv4 access is still required for hosts in IPv6 network SW IPv4-over-IPv6 Hub & Spoke Some hosts need to provide IPv4 service to the IPv4 Internet Operators (CERNET) need to support all apps & avoid xlate (NAT44 or NAT64) Use case study high-end client (host): Hope to have global IPv4 addr to support various apps even dynamically Servers (host): Move IPv4 servers to IPv6 networks without loss of IPv4 clients Having global IPv4 addr will be a Value-Added Service IPv4 Internet IPv4 Service NO NAT44 NO NAT64 NO NAT44 NO NAT64 IPv6 Edge Network 3

4. General Idea of Host 4over6 Leverage some global IPv4 addresses Operators hope to leverage their existing resource of IPv4 blocks Assign global IPv4 addr dynamically to host or CPE Bidirectional 4over6 tunnel Use bidirectional tunnel for traversing IPv4 traffic over IPv6 networks IPv4 Internet IPv4 Service NO 44 NAT NO 46 NAT NO 44 NAT NO 46 NAT Leverage IPv4 global address bidirectional 4over6 tunnel IPv6 Edge Network 4

5. Elements in Host 4over6 Tunnel Initiator(TI) Host or CPE in IPv6 edge networks Request global IPv4 addr when needed Establish 4over6 tunnel toward Tunnel Concentrator Tunnel Concentrator(TC) IPv4/IPv6 dual stack router as the 4over6 tunnel endpoint Perform encap/decap DHCPv6 server Allocate both IPv6 address and tunnel concentrator address to tunnel initiator Dynamically allocate host 4over6 address to tunnel initiator IPv4 Internet IPv6 Edge Network TI : host DHCPv6 Server TC IPv4 home network TI: CPE host 5

6. Stateless: DHCPv6 Extension Allocate tunnel concentrator IPv6 address draft-ietf-softwire-ds-lite-tunnel-option-03 Host 4over6 address ( IPv4-Embedded IPv6 address) NSP + global IPv4 addr + suffix draft-ietf-behave-address-format-09 New DHCPv6 option (OPTION_HOST_4OVER6_ADDR) to allocate this address: Implicitly allocate IPv4 addr by DHCPv6 OPTION_HOST_4OVER6_ADDRoption-len: 16 octets IPv4-Embedded IPv6 address 6

7. Stateless approach 4over6 Host Request 4over6 addr from DHCPv6 server Abstract embedded IPv4 addr and config IPv4 stack Tunnel initiator Encap/Decap TC: NO stateful mapping Need to inject a few IPv4 prefix into IPv6 RT Only in one IPv6 edge network (NSP-based) IPv4 network IPv4 Internet IPv6 Edge Network host DHCPv6 Server TC Request host 4over6 addr NSPIPv4Suffix Concentrator Addr v6 Src v6 Dest Global v4 Src v4 Dst payload Global IPv4 v6 Src v6 Dest Global v4 Src v4 Dst payload Global v4 Src v4 Dst payload v6 Src v6 Dest Global v4 Src v4 Dst payload Global v4 Src v4 Dst payload Concentrator Addr NSPIPv4Suffix CPE 7

8. CPE function DHCP46: request host 4over6 address from DHCPv6 server when host launch global DHCPv4 request to CPE Tunnel Initiator: Encapsulation/decapsulation IPv4 host No any change in CPE mode Stateless approach (CPE scenario) IPv4 Internet IPv6 Edge Network host DHCPv6 Server TC Request global ipv4 CPE DHCP46 Request host 4over6 addr Reply host 4over6 address CPE reply global IPv4 addr Global v4 Src v4 Dst payload v6 Src v6 Dest Global v4 Src v4 Dst payload 8 IPv4 network

9. IPv4 Internet Combination with Dual-Stack Lite: Host scenario DHCPv6 server Use the same DHCPv6 option to get the concentrator IPv6 address (draft-ietf-softwire-ds-lite-tunnel-option-03)draft-ietf-softwire-ds-lite-tunnel-option-03 Add an option for 4over6(OPTION_HOST_4OVER6_ADDR) Tunnel concentrator Outbound, differentiate by Src addr Public – host 4over6; Private – DS-lite Inbound Differentiate by Dst addr In CGN address pool – DS-lite; otherwise: host 4over6 IPv6 Edge Network Host4over6 SERVER DS-lite CLIENT TC Inform the TC IPv6 addr DHCPv6 Server Launch a DS lite process DHCPv6 with option HOST_4OVER6 Launch a host 4ovr6 process 9

10. What Host 4over6 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 to have full access to IPv4 without NAT Provide value-added service 10

11. Stateful approach of Host 4over6 Tunnel concentrator maintains global IPv4 addr pool Initiator uses both DHCPv6 & DHCPv4 Request TC’s IPv6 addr from DHCPv6 server with DS-Lite tunnel option Request IPv4 addr from DHCPv4 server ( TC ) with DHCPv4 over IPv6 tunnel Concentrator maintains the state of address mapping Host global IPv4 address: Host IPv6 address IPv4 Internet IPv6 Edge Network DHCPv6 Server TC 4over6 Host DHCPv6 TC IPv6 addr DHCPv4 over IPv6 tunnel Mapping (not per flow): Global IPv4 addr – IPv6 addr 11

12. Next step Set up a design team… cuiyong@tsinghua.edu.cn jianping@cernet.edu.cn Implementation on host/CPE/TC Ask for accepting as WG document Valuable comments Alain Durand, Yiu Lee, Olivier Vautrin, Chris Metz, Rajeev Koodli, Eric Nordmark, Cathy Zhou, Mingwei Xu, Xing Li, … 12 Welcome to join…