> From: Tarun2 Gupta [[email protected]]
> 
> Hi All
> 
> Consider the following scenario:
> 
> 
> UA 1                             B2BUA                         UA2
> Invite (From tag F1)
> --------------------------------->
>                                     Invite (From tag F2)
>                                     ---------------------------------->
>                                     200 OK (From tag F2, To tag F2)
>                                     <---------------------------------
> 
> As per Section 19.3 of RFC 3261,
> "When a tag is generated by a UA for insertion into a request or
> response, it MUST be globally unique and cryptographically random with
> at least 32 bits of randomness"

If the B2BUA accepts the 200 with F2 as both from- and to-tag, then it
must accept the BYE.

But more importantly, why is UA2 generating such a 200?  The chance is
less than 2^(-32) that the two tags would be the same if the to-tag
was generated according to RFC 3261.  It is almost certain that UA2 is
malfunctioning.  If that is fixed, the problem with the BYE vanishes.

Dale

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