1. 12/11/2010V6OPS Mobile Transition IETF 791 Mobile Use Case and Transition Guide Looking Ahead To New Draft Versions draft-zhou-v6ops-mobile-use-case draft-tsou-v6ops-mobile-transition-guide Cathy Zhou Tina Tsou Tom Taylor

2. 12/11/2010V6OPS Mobile Transition IETF 792 Background Basic mobile transition use case analysis is RFC 4215 (2005) Lots of tool development since then draft-korhonen-v6ops-3gpp-eps provides an architectural update draft-ietf-v6ops-v6-in-mobile-networks looks in more detail than RFC 4215 into the question of NAT placement draft-zhou-v6ops-mobile-use-case looks at the case of an operator under greater pressure than most, and adds detail to the analysis of deployment alternatives

3. 12/11/2010V6OPS Mobile Transition IETF 793 Mobile Architecture (LTE) UE eNode B Servin g GW PDN GW IPv4 / IPv6 provider- owned packet data network Provider or partner content and applications GTP-U or PMIPv6 tunnel GTP tunnel IPv4 or IPv6 Internet Possible domain boundary Serving Gateway (SGW) replaces SGSN Packet Data Network Gateway (PDN GW) replaces GGSN

4. 12/11/2010V6OPS Mobile Transition IETF 794 Scenarios RFC 4215 has the following scenarios: Dual Stack UE connecting to IPv4 and IPv6 nodes IPv6 UE connecting to an IPv6 node through an IPv4 network IPv4 UE connecting to an IPv4 node through an IPv6 network IPv6 UE connecting to an IPv4 node IPv4 UE connecting to an IPv6 node UE connecting to a node in an IPv4 network through IMS Two IPv6 IMS connected via an IPv4 network "IMS" analysis applies to other distributed applications. What has newer work contributed to the analysis?

5. 12/11/2010V6OPS Mobile Transition IETF 795 Dual Stack UE connecting to IPv4 and IPv6 nodes Details: no access network support for IPv6 Stage of migration: very early RFC 4215 advice (private IPv4 covered in separate slide): UE to IPv6 node should tunnel IPv6 in IPv4 Tunneling mechanism to be determined IPv6 communication is preferred to IPv4 communication going through IPv4 NATs to the same dual stack peer node. Operators strongly urged to IPv6-enable the SGSN and GGSN (SGW and PDN GW in LTE) as soon as possible More recent work: more tunneling mechanisms, 6rd. 3GPP updates to make IPv6 operation easier [Korhonen]. Proposal: recommend 6rd for this very early stage.

6. 12/11/2010V6OPS Mobile Transition IETF 796 IPv6 UE to IPv6 node through IPv4 network Details: access network IPv6-enabled, edge of IPv4 network somewhere beyond GGSN (PDN GW in LTE) Stage of migration: early RFC 4215 advice: network-initiated IPv6-in-IPv4 tunnel Could be static (within the operator's network) or dynamic Static tunnels operationally unscalable, should be eased by making parts of backbone dual stack as growth requires it More recent work: 6PE, gateway initiated 6rd (draft-tsou- softwire-gwinit-6rd). Proposal: provide pointers to the more recent work

7. 12/11/2010V6OPS Mobile Transition IETF 797 IPv4 UE to IPv4 node through IPv6 network Details: as it says Stage of migration: should not occur, because intervening network is likely to be dual stack rather than pure IPv6, pending phaseout of IPv4 UEs. RFC 4215 advice: none More recent work: gateway initiated dual stack Proposal: agree with RFC 4215. Do not pursue further.

8. 12/11/2010V6OPS Mobile Transition IETF 798 IPv6 UE connecting to an IPv4 node Details: no specific assumptions on network Stage of migration: late. Dual stack UE recommended until IPv6 usage is dominant. RFC 4215 advice: use special-purpose rather than general- purpose translation mechanisms. Choice of location in operator or external network. More recent work: NAT-PT deprecated. Current BEHAVE work on NAT 64. [Korhonen] recommends that new applications requiring direct end-to-end connectivity be built on IPv6. Proposal: review RFC 4215 recommendation to see if general NAT 64 should be used instead.

9. 12/11/2010V6OPS Mobile Transition IETF 799 IPv4 UE connecting to an IPv6 node Details: legacy IPv4 UE connecting to new IPv6 applications. Stage of migration: late RFC 4215 advice: UE won't be able to take advantage of the new application features even if the transport issue is solved. Applications will typically be proxied in any event. No action required. More recent work: not dealt with as a specific issue in [Korhonen] or draft-ietf-v6ops-v6-in-mobile-networks. Possible that applications will be dual stack. Proposal: accept RFC 4215 conclusion. No further discussion.

10. 12/11/2010V6OPS Mobile Transition IETF 7910 A Really Quick Look At IMS UE P-CSCF I-CSCF S-CSCF Applicatio n Server P-CSCF Othe r node Signalling Media IMS provides multimedia calls QOS-controlled media path SIP and SDP signalling

11. 12/11/2010V6OPS Mobile Transition IETF 7911 Call between UE and a node in an IPv4 network through IMS Details: UE is IPv6. Other node is non-3GPP. RFC 4215 makes the assumption that IMS is IPv6-only, based on an outdated 3GPP specification. Reasonable to accept assumption for late stages of migration. Stage of migration: late. RFC 4215 advice: interworking required. RFC 4215 provides challenges involved at application level (SIP and SDP signalling), and urges work on solutions in IETF. Example solution based on use of application-level gateway found to be unsatisfactory. More recent work: ICE (RFC 5245), other SIP and SDP updates. Requirement to use ICE is controversial. Proposal: use as example of challenges for application update.

12. 12/11/2010V6OPS Mobile Transition IETF 7912 Two IPv6 IMS Connected via an IPv4 Network Details: two IPv6 IMS islands connected by an IPv4 network. E.g., transit path between P-CSCF and S-CSCF includes an IPv4 network. Stage of migration: early RFC 4215 advice: special case of earlier slide (#6). Use IPv6- in-IPv4 tunneling. More recent work: as for slide 6. Proposal: nothing further to add.

13. 12/11/2010V6OPS Mobile Transition IETF 7913 Use of Private Addresses RFC 4215 says use of NAT will get expensive as size goes up. Current work on Large Scale NAT (LSN). Also work on reducing need for IPv4 addresses at dual stack UEs (gateway initiated dual stack lite). [Korhonen] points out that size of 10.0.0.0 address space is a good match for number of UEs served by a PDN gateway draft-ietf-v6ops-v6-in-mobile-networks analyzes use of NATs in depth Proposal: topic is already well covered and does not need further discussion.

14. 12/11/2010V6OPS Mobile Transition IETF 7914 Conclusion Despite all the past and ongoing work, there are still a few things to say about IPv6 transition in the mobility case Will update draft-tsou-v6ops-mobile-transition-guide to say what has been presented on these slides Value as a stand-alone document can be reviewed later