On Fri, 2005-11-18 at 07:23 +0100, Jeroen van Bemmel wrote:
> Yes, that's what I intended above (except that per Contact URI more than 
> just the expire time can be maintained). In my example the last Call-ID and 
> CSeq seen for that Contact URI are also maintained.

Although as far as I can tell, there is no need (within RFC 3261) to
maintain the last Call-Id and CSeq for the contact.

> The CSeq check only works if the UAC sends the same Call-ID each time. If 
> the second one it sends is different, there's a good chance that the third 
> will again be different. So I don't see the point of keeping more than 1 
> CSeq/Call-ID per UAC Contact (i.e. only the latest pair it sent).

It depends on exactly how the out-of-order tests are done.  After
reading 10.2.4, I was thinking that if the registrar received (for the
same contact) three REGISTERs with Call-Id 1 / CSeq 10, Call-Id 2 / CSeq
100, Call-Id 1 / CSeq 9, the last register should be ignored.  That
would require remembering the last seen CSeq for each Call-Id.

But reading 10.3, steps 6 and 7, it's clear that in that sequence, the
third REGISTER is required to be processed, and the registrar does not
need to remember the last seen CSeq for a Call-Id that did not create a
current binding.

Dale


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