Hi Joseph,
I think that for this to work, you would need an entitty (proxy or ALG) at
the NAT box. An ALG would replace the private IP in the Contact header of
the SUBSCRIBE with a public one, a proxy would record-route the SUBSCRIBE
such that it receives the NOTIFY on its public IP address
Regards,
Jeroen
----- Original Message -----
From: "Joseph Cheri" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Wednesday, September 28, 2005 6:47 AM
Subject: [Sip-implementors] Traversal of SUBSCRIBE/NOTIFY requests
throughSymmetric NAT
Hi All,
Can anyone please provide me pointers for the below mentioned query ?
1> Consider the following deployment scenario
[UA1] ---->NAT---->Presence Server--->[UA2]
Let us assume that UA1 is in private domain and is behind a symmetric NAT.
And the remaining entities (i.e. Presence Server and UA2) are in public
domain.
Suppose that UA1 (watcher) is not registered and wants to subscribe to UA2
through Presece server. Now as NAT is present the response 200 OK for
subscribe request will follow the same path and reach UA1(may be using
rport or the same connenction incase of connection oriented transport).
But for NOTIFY how does the call flow actually happens? The NOTIFY is
always sent on 'Contact' received in SUBSCRIBE request, and can be a
private IP. Hence NOTIFY sent to the private conatct will be dropped at
NAT. So shall the NOTIFY be sent on 'received' and 'rport' received in
initial SUBSCRIBE request ?
Is it that its possible to sent UA1 a NOTIFY only if UA1 sends a subscribe
with an rport paramter?
Is it that the UA1 sends a subscribe request with instance-id and flow-id?
(is this allowed // instance-id and flow-id are for Registration request)
or is there any other solution for the same.
Regards,
--Jose
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