----- Original Message -----
Sent: Wednesday, October 15, 2003 1:44 PM
Subject: RE: [Sip-implementors] Must Proxy forward or drop a 4xx, when 2xx is got from other leg?

Hi,

Please see my comments inline...
-----Original Message-----
From: Nataraju A.B. [mailto:[EMAIL PROTECTED]
Sent: Tuesday, October 14, 2003 3:07 PM
To: [EMAIL PROTECTED]; [EMAIL PROTECTED]
Subject: Re: [Sip-implementors] Must Proxy forward or drop a 4xx, when 2xx
is got from other leg?



----- Original Message -----
From: [EMAIL PROTECTED]
To: [EMAIL PROTECTED]
Sent: Tuesday, October 14, 2003 1:29 PM
Subject: [Sip-implementors] Must Proxy forward or drop a 4xx, when 2xx is
got from other leg?


Hi All,

I have a query in Forking Proxy behaviour.
(Incase this query has already been discussed, please give a pointer to that
mail thread)

The scenario is as below:
The Proxy gets a 4xx from the other branch,after it has got a 2xx from the
first branch.
Now should the Proxy forward this 4xx (or) drop this?

As per RFC Clause:16.7 Item9
----------------------------------
If the server transaction is no longer available to handle the transmission,
the element MUST forward the response statelessly by sending it to the
server transport.

=>This means that 4xx has to be FORWARDED statelessly as the Server
Transaction(ST) would have been deleted,as soon as forwarding the 2xx.

As per RFC Clause:16.7 Item5
----------------------------------
After a final response has been sent on the server transaction,
the following responses MUST be forwarded immediately:
-  Any 2xx response to an INVITE request
A stateful proxy MUST NOT ***immediately*** forward any other
responses.

=> This means that 4xx has to be DROPPED(?).
=>Here,***immediately*** refers to till some timer value or indefinitely?
These 2 clauses creates an ambiguity as to what is the expected
behaviour...........
Can someone please clarify?

[ABN]            here the 4xx must not be forwarded back UAC, it must be
DROPPED ......
here ,***immediately*** means no need wait for response staus on other
clients (If there are any)
 
[Prakash]=> Suppose I send a 4xx response,after say 10-15 minutes instead of
immediately,
then what the Proxy is supposed to do?Forward it statelessly?
[ABN] If there is no matching transaction then there is no need forward an failure response,
since the response forwarding is purely based on Via header. This could be the case when the a failure resposne received after it could have been timed out @ this proxy.....

Thanks,
Prakash.


#   [UAC]       [PROXY]    [UAS_A]         [UAS_B]
#     |     INV      |              |               |
#     |----------> |              |               |
#     |     100      |             |               |
#     |<-----------|    INV    |               |
#     |                |--------->|               |
#     |                |            INV              |
#     |                |----------------------->|
now there are 2 CT and 1 ST.
#     |                |     200    |               |
#     |     200      |<---------|               |
#     |<-----------|              |               |
now there will be only 1 CT and NO STs.
#     |              |             486              |
#     |              |<------------------------|
#     |  486(?)  |                |               |
#     | forward?|                |               |
#     |<---------|                |               |
#     |              |            ACK(?)           |
#     |              |            drop?             |
#     |              |------------------------>|
#     |              |                |               |
#     |              |                |               |
#

Thanks,
Prakash.
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