Subject: [SIP] Pre-loaded Route headers

From: Jonathan Lennox <[email-masked]>
Date: Fri, 3 Nov 2000 13:46:37 -0500 (EST)

I've been pondering details of the concept of "pre-loaded" Route headers --
Route headers that go in the initial transaction of a call, used to direct a
call to go through an outbound proxy server.

My question is, if you pre-load a Route header into an initial INVITE, do
those Route headers have to persist for the rest of the call?  Or do
subsequent transactions just build their Route headers based on the
Record-Routes that were inserted in that first transaction?

I think it would have to be the latter, since the destination UAS doesn't
see any of the pre-loaded Route headers.  The UAS is going to all its
routing based on those initial Record-Routes -- all the pre-loaded Routes
are stripped by the time the request gets to the UAS.

I was going to suggest that if you get a request with your own Route header
in it you be required to insert yourself as a Record-Route -- until I
remembered that you don't see Route headers for yourself.  (This causes a
lot of headaches, it seems.)

The problem is that this seems to be asymmetric with how Route headers
persist *after* the first transaction -- 2543bis says they remain even if
subsequent transactions don't put Record-Routes in for them.  This may be
the correct behavior, but it should probably be called out explicitly.

Thoughts?

-- 
Jonathan Lennox
[email-masked]

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From: "Hisham Khartabil" <[email-masked]>
Date: Mon, 6 Nov 2000 14:57:52 +0200

My questions are:

1. who would build this initial route header? It would have to be the user
2. how would this user know of the path?

Regards,
Hisham
Hotsip

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]On
Behalf Of Jonathan Lennox
Sent: Friday, 3 November 2000 8:47 PM
To: [email-masked]
Subject: [SIP] Pre-loaded Route headers

Thoughts?

--
Jonathan Lennox
[email-masked]