Subject: Topology descriptor - preference handling.

From: Ashok Khuntia <[email-masked]>
Date: Mon, 15 Nov 1999 08:42:42 -0600

There are two new parameters in topology descriptor, priority and
emergency indicator, in V12 of the MEGACOP document. The document says
that these parameters provide MG with information about a certain
precedence handling for a context. Can somebody explain this? My
understanding of the protocol is that commands inside a transacation are
executed in order. So if  commands 1 and 2 are in context 1 and commands
3 and 4 are in context 2, then they will get executed in order: 1, 2, 3
and 4. And the order is the same even if context 2 has a higher priority
than context 1. Is this correct?

Ashok Khuntia
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From: Tom-PT Taylor <[email-masked]>
Date: Mon, 15 Nov 1999 10:00:48 -0500

First point: the priority and emergency indicators are additional context
properties, not part of topology.

As I understand it, the primary reason for priority is to guide allocation
of resources when there is a resource shortage.  It is related to the MLPP
feature of ISUP.  I think in military systems calls of lower priority can
actually be cleared if necessary to accommodate calls of higher priority.
Brian Rosen has suggested that Priority should also affect ordering of
message transmission when ALF is being used.

The emergency indicator indicates that the call is associated with an
emergency service (e.g. 911 in Canada and the United States).  I would
interpret it as a hint to the MG to preserve the connection and to attempt
to reestablish it if it is broken.  This may require dialogue with the MGC.
Maybe we have to think about that.

> -----Original Message-----
> From: Ashok Khuntia [SMTP:[email-masked]]
> Sent: Monday, November 15, 1999 9:43 AM
> To:   [email-masked]
> Subject:      Topology descriptor - preference handling.
>