-----Original Message-----
From: Jinyan Su [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, May 08, 2001 12:16 PM
To: [EMAIL PROTECTED]
Subject: [Sip-implementors] Question about Record-Route
>
>Hi, there,
>
>I am reading the "new record-route text" at:
>http://lists.bell-labs.com/pipermail/sip/2000q4/004809.html
>
>In the proxy behavior section, it talks about a recommended scheme that to
add a record-
>route parameter to uniquely identify the proxy when the proxy inserts a
Record-Route
>header into the request and removes that parameter in the corresponding
200-class
>response. This is used to identify which iteration of the spiral that it is
in. I have a
>question about this scheme:
>
>When the request is being forwarded in a spiral way, the proxy might insert
Record-Route
>in some of these iterations and might not do so in the others. In this
case, the above
>scheme will be broken.
>
>Is there any amendment to the above scheme or is there some other ways to
enable
>modification of Record-Route headers in the response?
I believe the approach will still work. You really need to think about
spirals as if they were going through separate "virtual" proxies on each
pass. So, consider a request which spirals through a proxy P twice. The
first time is through virtual proxy P1, and the second time, virtual proxy
P2. P1 record-routes, P2 doesn't. When the response comes, it is first
processed by P2 (we know it goes to P2 because the Via headers contain
sufficient information in the branch-id to match the response to a
transaction). Since P2 didn't record-route, it doesn't attempt to strip the
parameter from the RR, or otherwise modify RR. P2 forwards it upstream. It
comes back to P once more, processed by P1. Since P1 did record-route, it
strips off the top parameter, modifies the RR, and passes it on.
-Jonathan R.
---
Jonathan D. Rosenberg, Ph.D. 72 Eagle Rock Ave.
Chief Scientist First Floor
dynamicsoft East Hanover, NJ 07936
[EMAIL PROTECTED] FAX: (973) 952-5050
http://www.jdrosen.net PHONE: (973) 952-5000
http://www.dynamicsoft.com
_______________________________________________
Sip-implementors mailing list
[EMAIL PROTECTED]
http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
