Hi Satya:

The choice of keeping the version number can be easily explained if one
considers backward compatibility. Think of interoperability between a
3261 componenet (UA/PROXY etc.) and an old 2543-compliant component. If
you use a new version number in the 3261 component the 2543 component will
fail. The magic cookie trick is in effect a version number as you have noted
but it allows for backwards compatibility.

Ranga.

On Wed, 4 Sep 2002, Yadavalli, Satyamurthy wrote:

> Kirill,
> I did read this section which explicitly talks about branch ID:
> "..so that servers receiving the request can determine that the branch ID
> was constructed in the fashion described by this
> specification.."
>
> Ofcourse, this may be used as (an indirect) means to distinguish between the
> two versions.
>
> Sounds strange though that the SIP/Version was not used for a SIP entity to
> explicitly say that it is RFC3261 compliant...probably there were some
> reasons for doing so (like many old entities doing strict check for 2.0
> instead of greater than or equal to 2.0)...may have been discussed on the
> mailing lists much earlier.
>
> Thanks,
> Satya

-- 
M. Ranganathan
Advanced Networking Technologies Divsion
National Institute of Standards and Technology (NIST)
100 Bureau Drive, Stop 8920, Gaithersburg, MD 20899.
Tel: 301 975 3664 ; Fax: 301 590 0932

Advanced Networking Technologies For the People!


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