Multiple Addresses in Transport - For Discussion

1. Multiple Addresses in Transport - For Discussion Allison Mankin

2. Setting • Hosts have multiple addresses: • IPv4 (private realm or global) • IPv6 (link-local, global) • Multiple global addresses due to multi-homing • Addresses of additional interfaces (e.g. SIGTRAN usages) • Address obtained from STUN

3. Multiple Addresses Tackled By Transports • TCP: not handling multiple addresses • SCTP: associations have multiple addresses and addip extension is working on its security [tsvwg] • DCCP: address (and port) mobility moved from base protocol to an extension document. This will probably be experimental. Mobility means changing from one of your addresses to another. [dccp]

4. Note • The handler of the addresses in the protocols just mentioned is the session layer. • We just happen to combine session with transport.

5. Session and ?? Protocols • SIP: with an SDP ANAT group in the offer-answer, one IPv4 and one IPv6 address are offered for connection choices. (Proposed work). [mmusic] • ICE (Internet Connectivity Establishment): uses diagnostics to find a global address UDP only. Other transports TBD. [mmusic] • NSIS nat/firewall traversal application is considering a multi-address model. Output would be the reservation whose nat count had been lowest (Proposed work) [nsis]

6. Crux of the Discussion • The transport area has multiple approaches to multiple addresses • Varied services, differing breadth • Then there are multi-homing and host identity protocol (in the ops and internet areas) • Can/need we make this more consistent?

7. Multi6 and HIP • Multi6 (OPS Area) and HIP (INT Area) • Original tens of proposals with tens of goals are coming down to some coherence • Largest goal of scaling the routing system for multi-homing, with some other benefits • My view • Survival long-lived transport not goal

8. Multiple Addresses in Multi6/HIP • NOID: Identifier is one of the global IPv6 addresses, other addresses are locators and are not seen. • HIP/WIMP: Identifier is internal application only. • Main point is that all mask locators from session layer.

9. Conclusions/Directions • Generalize, use some transport work more? ICE? • Is the identifier work compatible with transport, session layer goals? • Should there be transport elements of source address selection (when connectivity gives multiple choices)? • Which layers should determine address selections and why?