RE: PReserving ids when changing providers (was:RE: to be draft-ohta-multi6-8plus8-00.txt)

["Ayyasamy, Senthilkumar \(UMKC-Student\)" <saq66@umkc.edu>]

>It is not exactly "hardcoding". SIP payloads carry the IP addresses to
>be used for initiating media sessions, but the protocol also has
>provisions for changing these addresses if the SIP agent's location
>happens to change. It is much easier to move a session to a new location
>by telling the peer about the new location than by updating a name
>service and hoping that the peer will find out. 
 
But, the bottleneck is shifted to STUN/Teredo servers instead of
name servers (with the caveat that it doesn't allow all types of 
traversal through NAT. esp TCP.)

>In any case, there is more than performance at stake. We must also to
>consider privacy. A SIP agent will only reveal its current location to
>the peers with whom it agrees to establish a session. This is very
>different from publishing a mapping between identifier and location in a
>globally accessible name service.
 
we can still maintain privacy in such a global mapping service. It 
depends on the design of the id/loc mapping service (but it depends
on the type of identifier; HIT/HIP can provide anonymity.) Also,
privacy can further be enhanced by having a stack of identifiers 
to route packets. In any case, a HIP related RG will concentrate
on these issues.
 
But, I would very much like the id/loc mapping to mirror SIP 
like design; rather than new overlay infrastrcuture (DHT
seems costly from a management perspective.)

>Not to say that SIP has got everything right. The payload format only
>allows for one IP address per media stream, which is problematic when
>the host is multi-homed or multi-addressed.
 
so, we need a new SDP description?