[chord] Chord and SIP

[Johnston, Alan]

Hi,

I have recently learned about the Chord protocol and its possible
application in P2P communications systems through papers from Columbia
University (http://www1.cs.columbia.edu/~kns10/research/p2p-sip/) and
William and Mary College (http://p2psip.org/).  I have also read a
number of excellent papers and tutorials on the topic, probably written
by some of you!

As an active IETF participant who has been involved in SIP (Session
Initiation Protocol) communications systems, I have also been a user of
Skype which clearly demonstrates the potential of P2P in this space.
>From what I have read, Chord's DHT is much more advanced than Skype's
simple flooding searching.

In discussions with other SIP experts, I have realized a differences of
opinion with others looking into P2P.  I had assumed that SIP could
utilize the Chord protocol for discovery (use a SIP URI as a search key
and get back the IP address of the node that has the current address of
that URI) then run as normally.  However, others are proposing that the
Chord DHT algorithm be run *over* SIP.  That is, messages between peers
used to establish, modify, and query peers would be carried over SIP
messages.  

I was hoping to get some feedback from you on this approach.  I am a SIP
expert so I have a good understanding of the problem space but I could
use some help in hopefully reusing as much of your excellent work as
possible rather than trying to reinvent it.

Any help will be greatly appreciated.

Thanks,
Alan Johnston
sip:alan at sipstation.com