Subject: [sipcore] 4244bis-05: Multiple forks from the UA

From: "Worley, Dale R (Dale)" <[email-masked]>
Date: Wed, 22 Jun 2011 16:52:59 -0400

In regard to the "root" of the History-Info tree, as the draft is written, we are already
requiring the possibility of H-I entries with indexes "2", "3", etc., that is, siblings of
the entry "1" that the phone creates.

How?  The phone may receive a 3xx response to its first request.  Per the rules
of the draft, the new requests generated due to a 3xx response to request "1"
are siblings of request "1", and so are numbered "2", "3", etc.

One consequence of this is that if we consider the H-I entries as nodes in a
tree, we have to allow that the root of the tree is *not* represented by an H-I entry,
and that the H-I entries with single integer index-vals are children of the root.

Another consequence is that this technical problem is solved:

    [Also need to take care of the case where the UAC generates several
    requests as forks of a theoretical ancestral request, as is used in
    draft-ietf-bliss-call-completion.  It seems like they should have
    index=1, index=2, index=3, etc.]

Since entries "1", "2", "3", etc. can be generated by normal redirection, H-I processing
software should not get confused when a UA generates more than one initial fork.

Dale