Hi,
The scenario is a peer (JP) joins a ring of two peers: AP and NP, where
AP is the admitting peer of JP. Referring to Section 9.4 of the base-11
draft, step 7, AP sends an UPDATE to JP, immediately followed by step 8,
AP sends another UPDATE to NP.
If JP uses the technique discussed in thread "Clarification of initial
attach procedure" in which JP did not (or failed to) PING and ATTACH to
NP before JOIN, then after step 8, both JP and NP could simultaneously
send ATTACH to each other (via AP).
It's possible that both JP and NP receive the ATTACH request from the
other before receiving the reply to its own ATTACH request. The result
is two ICE checks may commence independently and lead to in two TLS
overlay links between JP and NP.
JP NP
--------- ---------
ATTACH_r1 ---->
<---- ATTACH_r2
ATTACH_a2 ---->
<---- ATTACH_a1
ICE-1 <--->
<---> ICE-2
TLS-1 <--->
<---> TLS-2
Here is the problem. The draft does not define a heuristic to choose
one ATTACH/ICE/TLS among the two and drop the other. For example, a
simple one could be comparing the transaction ID of both ATTACH as an
unsigned 64bit integer and drop the lesser one.
Any opinions on this?
Thanks
--Michael
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