1. IETF 80 th Problem Statement for Operational IPv6/IPv4 Co-existence 3/31/2011 Chongfeng Xie (xiechf@ctbri.com.cn) Qiong Sun (sunqiong@ctbri.com.cn)

2. 2011 Current Situation ISP: facing the biggest pressure of IPv4 address shortage ICP: lacking of enough motivation to migrate to IPv6 Manufacture: wondering what to do next… MAN Access Network CPE PC Mobile device BRAS/SR/ PDSN Service Platform AAA Network Management System ICP 2

3. 2011 Network Architecture The placement of AS (Address Sharing) Router has different impacts: Centralized : reduce cost, easy to manage and traffic LAES, performance bottleneck Distributed : high cost, hard to manage and traffic LAES, less performance requirement AS Router would be suitable for centralized placement 3 Backbone Network Metro Network Access Network CPE PC Mobile device BRAS/SR/ PDSN Service Platform AAA Log server LAES DNS AS Router Optional Placement AS Router Address Sharing Router

4. 2011 Communication Scenarios IPv6 is a final way to solve address shortage; however, there is not much IPv6 content. IPv4/IPv6 will co-exist for long period. Two major scenarios: IPv4 IPv4 for most current applications and IPv6 IPv4 for P2P applications and future IPv6-only ones. DS-LiteA+PStateless NAT64 / dIVI Stateful NAT64 NAT444 +IPv6 IPv4 IPv6 IPv4 IPv6 IPv4 IPv6 IPv4 IPv6 IPv6 IPv4 IPv6 IPv4 IPv6

5. 2011 End-to-End transparency and Scalability 5 DS-LiteA+PStateless NAT64/dIVI Stateful NAT64 NAT444 +IPv6 CGN problemBetter Core stateless Better Core stateless CGN problem It is important to keep the simplicity in core network and leave the intelligence to end systems. It should be scalable, easy for new applications to deploy in operational network. CGN would bring much complexity to the core of Internet, which includes transport-layer port mapping and ALG. CGN would also bring a lot of cost for ISPs.

6. 2011 Addressing and Routing 6 DS-LiteA+PStateless NAT64/dIVI Stateful NAT64 NAT444+IPv6 Address of the tunnel end to be passed Changes to address allocation related to the address format, address of the tunnel end to be passed Some changes to address allocation related to the address format No specific requirement Private IPv4 addressing Existing ISPs who adopt PPPoE/PPPoA need to allocate PD-prefix and WAN-interface address, and CPE would re-allocate IPv6 addresses to end systems. Address allocation system would setup the corresponding routing entries for a given customer. ISPs may adopt flexible address rules, no extra requirements on address format and address allocation, etc.

7. 2011 Address usage and consumption 7 DS-LiteA+PStateless NAT64/dIVI Stateful NAT64 NAT444 +IPv6 Dynamic sharingStatic sharing Dynamic sharing IPv4/IPv6 transition solutions would need address sharing, including dynamic and static ones. Nowadays, most applications consume many concurrent sessions, With address multiplexing, IPv4 address shortage problem could already be largely released. Static sharing is generally sufficient in the near future

8. 2011 User management and logging requirement 8 DS-LiteA+PStateless NAT64/dIVI Stateful NAT64 NAT444 User type: IPv6-only Add IPv6 feature Logging: Session-based User type: IPv6-only Add IPv6 feature Logging: No binding table User type: IPv6-only Add IPv6 feature Logging: No binding table User type: IPv6-only Add IPv6 feature Logging: Session-based User type: Dual-stack Add dual stack feature Logging: Session-based User management system, e.g. AAA, etc., to implement accounting and billing. Transition period would have multiple types of users, e.g. IPv4-only, IPv6-only, or dual stack, etc. ISPs and ICPs have the requirements of lawful interception and surveillance. Session-based logging would bring a great burden to existing software-based logging system. +IPv6

9. 2011 CPE issue 9 DS-LiteA+PStateless NAT64/dIVI Stateful NAT64 NAT444+IPv6 Tunneling+IPv6NAT+ Tunneling +IPv6 dIVI: NAT+ translation+IPv6 IPv6-featureIPv6+NAT44 CPE is more than a technical issue, but rather a business strategy. And different ISPs have their own situations. CPEs in routed mode have to be upgraded to support IPv6. And cost is extremely huge due to the large number of customers. Most IPv6 transition solutions would need to take additional modifications to CPE, apart from native IPv6 support. ISPs sometimes could not fully control customers CPEs.

10. 2011 Summary There is a set of operational requirements related to complexity and as a result of scalability Existing solutions for IPv4 address sharing is operationally complex We need more scalable address sharing mechanism to reduce the state, cost and complexity of core network There are alternatives that make life a lot easier for operators

11. 2011 Summary We prefer a solution with Good IPv6 support and be helpful for IPv6 development Better scalability Stateless ones without address constraint should be our direction Keep state as few as possible in core network, only maintain per-subscriber state entries in core network, and state should be stable. Flexible addressing Little modification to existing addressing and routing system Define flexible addressing plan for different purpose

12. 2011 12 Thank you