Subject: [Sip] Query on History-Info.

From: Siddharth <[email-masked]>
Date: Thu, 11 Dec 2008 19:01:19 +0530

Hi all,

I had a quick query on History-Info (RFC 4244). Apologies if this has
been discussed already. If so, I would be grateful if you could
provide the pointer to the relevant thread.

Once a proxy determines that it may include the History-Info header
for a particular request (based on local policy, privacy settings etc)
should it insert a History-Info header only if the proxy had done a
retargeting for this request? Or should it insert a History-Info
header irrespective of whether the request uri is changed by itself or
not?

The following text in the RFC: "Note that in the case of loose
routing, the Request-URI does not change during the forwarding of a
Request; thus, the capturing of History-Info for such a request would
result in duplicate Request-URIs with different indices." seems to
suggest that the proxy should always insert the History-Info header
even if the Request-URI is not changed. Is this understanding correct?

Thanks and Regards,
Siddharth
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---

From: "Mary Barnes" <[email-masked]>
Date: Thu, 11 Dec 2008 13:12:50 -0500

If the proxy is supporting History-Info, it should add a header for
every retarget or forwarding of a Request.  For Loose routing, the proxy
is retargeting - it's just capturing the next hop in the Route header
only. The text in RFC 4244 indicates that with Loose Routing, the
Request-URI is the same in each entry, but you do still get information
as to the number of hops, etc. This could still be useful to some
applications - for example, you can still build the tree for the path of
the request. Obviously, there are some limitations to the usability of
H-I in these cases. 

There is text in RFC 4244 in section 4.3.3.1 that specifies H-I is added
as a request is forwarded, so it should insert H-I irrespective of
whether the Request URI has changed as you suggest below. 

It might be helpful to both add an example showing how the trees of the
path of the request are helpful, as well as showing an example in the
case of loose routing when we update RFC 4244. 

And, perhaps something to clarify is that in the case of loose routing
the hops are reflected in the Route Header. 

Regards,
Mary. 

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of
Siddharth
Sent: Thursday, December 11, 2008 7:31 AM
To: [email-masked]
Subject: [Sip] Query on History-Info.

Hi all,

I had a quick query on History-Info (RFC 4244). Apologies if this has
been discussed already. If so, I would be grateful if you could provide
the pointer to the relevant thread.

Once a proxy determines that it may include the History-Info header for
a particular request (based on local policy, privacy settings etc)
should it insert a History-Info header only if the proxy had done a
retargeting for this request? Or should it insert a History-Info header
irrespective of whether the request uri is changed by itself or not?

The following text in the RFC: "Note that in the case of loose routing,
the Request-URI does not change during the forwarding of a Request;
thus, the capturing of History-Info for such a request would result in
duplicate Request-URIs with different indices." seems to suggest that
the proxy should always insert the History-Info header even if the
Request-URI is not changed. Is this understanding correct?

Thanks and Regards,
Siddharth
_______________________________________________
Sip mailing list  https://www.ietf.org/mailman/listinfo/sip
This list is for NEW development of the core SIP Protocol Use
[email-masked] for questions on current sip Use
[email-masked] for new developments on the application of sip
_______________________________________________
Sip mailing list  https://www.ietf.org/mailman/listinfo/sip
This list is for NEW development of the core SIP Protocol
Use [email-masked] for questions on current sip
Use [email-masked] for new developments on the application of sip