Sergio,
Thank you for clarifying your question.
Let me try and provide some more detail, responses are always sent
from
the UAS to a UAC and are always routed based on the via header
never the
flow token. The flow token is only used for routing of initial
requests
from the edge proxy (UAC) to the client (UAS).
Section 4.3 defines the UAC procedures (it is titled sending
requests)
and strongly recommends that the UA include the rport in the via
header.
When the Edge Proxy gets the INVITE, it will populate the rport
parameter in the UAC inserted via head with the source port in the
UDP
header of the received packet. It will also insert the receive
parameter
into the same via header entry which contains the source IP
address in
the IP header of the received packet. The Edge Proxy then adds its
own
via header entry and forwards this INVITE along.
When the edge proxy gets back the response, it will look at the
top most
Via header which contains the rport and receive parameter. The Edge
Proxy will then forward the response to the UAC using these
parameters
which are routable since they represent the WAN interface of the NAT.
The flow token never comes into play in this case.
This is all defined in RFC 3581 (An Extension to the Session
Initiation
Protocol (SIP) for Symmetric Response Routing)
I hope this helps clarify the situation.
Kevin
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Sent: Friday, April 20, 2007 8:59 AM
To: Kevin Johns
Cc: [email protected]; Cullen Jennings; Rohan Mahy
Subject: RE: [Sip] outbound08 - Handling Responses in Edge proxy /
Viavs.Flowtoken
Hi,
Thank you for your answer.
Perhaps I should emphasize that I am always talking about Edge
Proxy
behavior handling incoming Responses to be forwarded to a UAC over an
existing flow.
It seems that your answer is related to handling Responses in
the UAC,
not in the Edge Proxy. Nevertheless I add my comments below:
Outbound expects that rport is used in the via header for routing of
responses (for UDP that is) see the note in section 4.3.
I understand that section 4.3 is for UA behavior.
Responses are
routed as defined in 3261 for TCP.
Yes, but in the case of forwarding Responses to a flow in an Edge
Proxy, I understand that the proxy uses the flowtoken information,
thus
discarding any consideration of the Via-header parameters
(different to
3261 approach).
So.. shouldn't outbound-08 draft explain the case of Responses
handled
by the Edge Proxy? By common sense I guess that the Response
should use
the destination stated in the flowtoken, but, as
outbound-08 did not formally specify this case, why I could not avoid
considering the destination in the Via-header (although it wont work
with NAT)?
Regards,
Sergio
Quoting Kevin Johns <[EMAIL PROTECTED]>:
Sergio,
Outbound expects that rport is used in the via header for routing of
responses (for UDP that is) see the note in section 4.3.
Responses are
routed as defined in 3261 for TCP.
Kevin
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Sent: Thursday, April 19, 2007 8:52 AM
To: [email protected]
Cc: Cullen Jennings; Rohan Mahy
Subject: [Sip] outbound08 - Handling Responses in Edge proxy / Via
vs.Flowtoken
Hi,
I have a question related to handling Responses that are going
to be
sent over a flow in an Edge proxy.
In "5.3. Forwarding Requests (outbound08)" I read that a
Request is
forwarded to a flow using the information retrieved from the flow
token (and that it is found in the Route-header).
Now I am considering how is the case for Responses.
Should we consider the same behavior? i.e. forward a Response
over a
flow using the flowtoken found in the Path-header?
In 'non-outbound SIP', as far as I understand, Route Header forces
the routing in Requests, and Via-header forces routing in Responses.
So... should we avoid any consideration to the information
stored in
the topmost Via-header when proxying a Response? (And instead use
the
information in the flowtoken ?)
I think that the answers is yes, since the Via could contain a
private address in the case of a NAT in the middle. Then,
shouldn't be
mentioned the response case in the draft?
Regards,
Sergio
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