Subject: [Ieprep] IEPREP SIP REQ-2

From: "Gunn, Janet" <[email-masked]>
Date: Mon, 14 Oct 2002 15:34:32 -0400

"REQ-2: Independent of particular network architecture: The
             mechanism should work in the widest variety of SIP-based
             systems. It should not be restricted to particular
             operators or types of networks, such as wireless networks
             or protocol profiles and dialects in certain types of
             networks."

It depends on whether we are talking about a mechanism for marking (i.e. a
labeling) or a mechanism for providing priority.

If it is a mechanism for providing priority, I don't have a problem with
using different mechanisms in different types of networks (e.g. multiple
priority levels in a low bandwidth sub network, but a single priority level
in a high bandwidth sub network).

If it is a mechanism for marking  priority, then it is certainly desirable
to have the same marking across different technologies.  But there do exist
systems on the telephony side that use different markings in different sub
networks.  This imposes additional requirements on the gateways between
these sub networks, but it can be done.
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From: Henning Schulzrinne <[email-masked]>
Date: Mon, 14 Oct 2002 17:17:26 -0400

> in a high bandwidth sub network).

As discussed earlier in this general thread, "collapsing" priorities 
into a smaller set of actually implemented behaviors is an 
implementation choice that should not be visible to outside parties.

> these sub networks, but it can be done.

However, even if the scheme differs, the sending side should simply find 
out about the schemes, rather the deduce them indirectly. ("Destination 
network uses bit twiddling foo, so I need to use namespace bar" would 
not be good.)

Generally speaking, there is currently no way for the sending system to 
find out whether the gateway terminates in analog circuits, ISUP, bush 
drums, radio circuits or smoke signals. ("Add additional oily rags for 
high-priority calls.")