Subject: RE: [Sip] Comments on draft-ietf-sip-hop-limit-diagnostics-00

From: "Samir Srivastava" <[email-masked]>
Date: Fri, 3 Mar 2006 14:20:02 -0600

Hans described my concerns clearly. 

Additionally, In this case we are more concerned about the via. RR is
second important header.
If only RR is pruned, it should indicate "4 RR are preserved " if via is
also pruned,
It should state "RR is pruned, and only top 4 via are preserved" . As
this is debugging utility,
If my proxies are doing record routing, and If I see mismatch in RR and
via headers in response,
I might suspect there is something wrong in record routing logic too. 

Thx
Samir

-----Original Message-----
From: Hans Persson [mailto:[email-masked]] 
Sent: Friday, March 03, 2006 7:38 AM
To: Scott Lawrence
Cc: Srivastava, Samir [SC100:8826:EXCH]; [email-masked]
Subject: RE: [Sip] Comments on draft-ietf-sip-hop-limit-diagnostics-00

fre 2006-03-03 klockan 10:24 -0500 skrev Scott Lawrence:

> If what you are asking is if there is something in the response that 
> tells the recipient it is not the complete set of headers, then the 
> answer is that at present there is not.
> 
> If you are asking whether or not it is ok to also remove some of the 
> Via and RR headers, then I would say that doing so would dramatically 
> reduce the utility of including anything; in fact, it might be worse 
> than returning nothing at all.

I interpreted his question as asking whether it would be possible for
the recipient of the 483 to tell whether the returned set of headers was
complete or not. If Via/Route headers have been pruned, knowing this
would be much more important than if just User-Agent/Subject/etc has
been removed.

However, I still see a use for something like 

   SIP/2.0 483 Too many hops
   From: Sip Send <sip:[email-masked]>;tag=612f37e7
   To: sip:[email-masked]
   Call-Id: [email-masked]
   Cseq: 1 INVITE
   Via: SIP/2.0/TCP 10.1.1.20:40221
        ;branch=z9hG4bK-931ea14405e9da8c95cf4ed60a71f59f
   Content-Type: message/sipfrag
   Content-Length: whatever
   Date: Fri, 14 Oct 2005 15:27:47 GMT

   INVITE sip:[email-masked] SIP/2.0
   Record-Route: <sip:192.0.2.162:5080
        ;lr;a;t=612f37e7;s=96e09e8e8c93a8c60bf460029847f4b1>
   Via: SIP/2.0/TCP 192.0.2.162
        ;branch=z9hG4bK-42e47bba67559bd9a3da1934a70bbc37
   Via: SIP/2.0/TCP 192.0.2.162:5080
        ;branch=z9hG4bK-50d909f1209f7a820de85c7831846330
   Via: SIP/2.0/TCP 192.0.2.162
        ;branch=z9hG4bK-994f162bc179fb75093166fabbfd13c7
   Via: SIP/2.0/TCP 192.0.2.162:5080
        ;branch=z9hG4bK-708842ad6ea22f8fa6e39c503d3d803e
   X-Comment: Only top four Via headers preserved.

if the message size needs to be kept down. I'm not saying that X-Comment
is necessarily a kosher way to get that information across, but you get
the idea. If I want to figure out what happened to get where we ended
up, I need to send the same request again, but with a lower Max-
Forwards.

Hans

-- 
Hans Persson <[email-masked]>    Ingate - Firewalls with SIP & NAT
Ingate Systems AB  +46 13 210877   http://www.ingate.com/

Private: <[email-masked]>  http://www.lysator.liu.se/~unicorn/

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