Vivek,
I think the issue you talked about is how to identify which REGISTER the
200(register) responds to,
I think RFC3261 sec 17.1.3 Matching Responses to Client Transactions has
already given the solution.
Another question is if you give REGISTRA the internal ip addr, how would
you expect the incoming request go?
i.e, which destination ip addr would incoming INVITE ueses? the internal
ip addr?
-Rockson
-------------------------------------------------------------------------
I clarify the same,
UA1 NAT1
REGISTRAR
----------------REG1----------------->
src ip: 10.0.0.1 port 5060
contact:10.0.0.1:5060
----------------REG2----------------->
src ip: 59.162.252.82
port 8888
contact: 10.0.0.1:5060
In the above scenario, UA1 is behind the NAT and 'src ip' is referring
as
Network Layer address. When REGISTER passes through NAT (L3), contact
remains the same. Due to symmetric response implementation on REGISTRAR
side, all the responses are sent back only to '59.162.252.82:8888'.
UA2
NAT2 REGISTRAR
-----------REG3---------->
src ip: 10.0.0.1 port 5060
contact:10.0.0.1:5060
----------------REG4----------------->
src ip: 199.100.100.100
port
9999
contact: 10.0.0.1:5060
Now, in above scenario which is different LAN network from scenerio1,
UA2
has assigned the same IP:Port as UA1. UA2 sends the REG request using
same
SIP-Id/ Authentication credentials as used by UA1. REG message passes
through NAT (L3) and contact remains the same.
Now, REGISTRAR has two contacts binding for this user. When REGISTRAR
sends
200 OK for REGISTER message to UA2, this 200 OK will include both the
bindings of user and both the contact bindings will have same value viz
'10.0.0.1:5060'. Now how the UA2 would identify its own binding to get
the
expiry timer allocated by registrar to UA2.
--Vivek
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