> Within RFC 2543 section 6.40.5, is the following paragraph:
>
>   The "branch" parameter is included by every forking proxy.
>   The token MUST be unique for each distinct request generated
>   when a proxy forks. CANCEL requests MUST have the same
>   branch value as the corresponding forked request. When a
>   response arrives at the proxy it can use the branch value to
>   figure out which branch the response corresponds to. A proxy
>   which generates a single request (non- forking) MAY also
>   insert the "branch" parameter. The identifier has to be
>   unique only within a set of isomorphic requests.
>
> From this text, all forking proxies should include the "branch"
> parameter.  However I was wondering, even though it is a "MAY"
> for non forking proxies to insert this parameter, is there any
> that do?

I cannot specifically comment on any implementation
that may or may not do this; however, I might note
that the branch parameter has been mandatory for a
very long time, since it has traditionally been used
to do loop detection, amongst other things.

Of course, since RFC 2543 did not mandate this
parameter, it is entirely possible that you will
run into an implementation that doesn't insert.
But since I suspect (unfortunately, I cannot check
at the moment) that branch parameters have been
mandatory since bis-00, it is quite unlikely.

We're currently "on" bis-05. &:)


 - Jo.
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