[Sip] comments on draft-ietf-sip-hop-limit-diagnostics-03
Jonathan Rosenberg <jdrosen@cisco.com> Fri, 07 July 2006 06:04 UTC
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Date: Fri, 07 Jul 2006 02:04:32 -0400
From: Jonathan Rosenberg <jdrosen@cisco.com>
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Subject: [Sip] comments on draft-ietf-sip-hop-limit-diagnostics-03
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major issues: Well, no change here in these. I think we need more discussion on them: 1. I still think this mechanism is applicable outside of max-forwards violations. The current text limits it to 483. 2. I agree with Cullen that we do need to specify a size limit for the response. Having thought about it more, I'm worried that the sipfrag body can't be more than 200 bytes! Consider a request that loops a lot. At some point, the via header itself will grow sufficiently to cause the mesage to switch from udp to tcp. That happens at the point at which the udp request exceeds 1300 bytes. For a response to that request to be also sent over UDP with no fragmentation, the response cannot be larger than the request by more than 200 bytes. Now, you might argue that proxies often strip Via's, and that a small max-forwards might never get the request to pop over to tcp. However if you are looking for a safe value, its 200 bytes. Thsi might motivate us to look at something different to return the data to the client, rather than in that response. Another option is content indirection. minor issues: > The SIP protocol imposes a limit on the number of hops a request can > transit on the way to its destination. The number of hops remaining > for the request is carried in the Max-Forwards header, and is header field > request has traversed a series of proxies, the response follows the > Vias back to the requester - in the case of a typical 483 response it > can be difficult to determine even what server the response came same comment as on -02. Difficult implies that its possible, just hard. Its NOT possible. > A Warning header with a warn-code of 399 that identifies the > system returning the error. header field > If including all Via and Route headers is still too large, the > implementation SHOULD remove the oldest Vias (those nearest the > message originator) until the size is acceptable; the only exception > to this rule is when . when....? Thanks, Jonathan R. -- Jonathan D. Rosenberg, Ph.D. 600 Lanidex Plaza Cisco Fellow Parsippany, NJ 07054-2711 Cisco Systems jdrosen@cisco.com FAX: (973) 952-5050 http://www.jdrosen.net PHONE: (973) 952-5000 http://www.cisco.com _______________________________________________ Sip mailing list https://www1.ietf.org/mailman/listinfo/sip This list is for NEW development of the core SIP Protocol Use sip-implementors@cs.columbia.edu for questions on current sip Use sipping@ietf.org for new developments on the application of sip
- [Sip] comments on draft-ietf-sip-hop-limit-diagno… Jonathan Rosenberg