Subject: [AVT] draft-ietf-mmusic-ice-19 question

From: Jim Kleck <[email-masked]>
Date: Tue, 25 Aug 2009 08:56:56 -0700

In looking at draft-ietf-mmusic-ice-19, we have run into a
point of confusion. Our understanding of the draft is that all
local candidates for a particular component for a mediastream can
use the same host IP Addr & port for gathering candidates and for 
sending and receiving connectivity checks. However, section 
7.2.1.4 (which deals with the ICE agent processing a received 
Binding Request) states:

   Next, the agent constructs a pair whose local candidate is equal to
   the transport address on which the STUN request was received, and a
   remote candidate equal to the source transport address where the
   request came from (which may be peer-reflexive remote candidate that
   was just learned).

If all local candidates for a component have the same host IPadd & port, 
how can the local agent determine which transport address the remote
agent sent the request to (which I assume is the first transport address
referenced in the above quote from the draft)? I dont see anything in 
the STUN Binding Request pkt which identifies the target candidate,
nor does the IPaddr:port the request was received on identify the target
candidate. Or does the local agent actually need a different host IPaddr
and port for each local transport address (or at least a different 
host IPaddr & port for host and relayed candidates)?

James Kleck
8x8, Inc.