Subject: [Sipping] Re:draft-camarillo-sipping-uri-list-02.txt

From: Paul Kyzivat <[email-masked]>
Date: Fri, 09 Apr 2004 18:05:34 -0400

Section 4 says:

    As for any other SIP request, the size of requests carrying URI lists
    MUST NOT exceed 1300 bytes, unless the user agent client has positive
    knowledge that the message will not traverse a congestion-unsafe link
    at any hop, or that the message size is at least 200 bytes less than
    the lowest MTU value found en route to the server.

I was curious about the implications of this, so I did some counting. I 
took the example in section 9 and stripped out all the leading blanks to 
get a plausible size estimate. The number I got was 1242, with four urls 
in the list. Each additional URL (of the size in the example) adds 37 
bytes. So a list with more than 5 urls exceeds the 1300 byte limit.

That says to me that this technique is pretty much useless except in 
carefully controlled networks, or when compression is used. Seems pretty 
limiting. So it seems likely that in practice content indirection will 
have to be used.

	Paul

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