Subject: Re: Topology

From: Chanchal Hassija <[email-masked]>
Date: Fri, 20 Oct 2000 13:05:32 +0530

Hello Paul,

The topology is with respect to a context and hence is not a command level
descriptor.......................So during the life-time of a
context......whatever topologies come in various actions get applied to the
context..............one after the other........If at any point of time you
refer to a term T1 in a command, then the following statements explain ---

*) If at any point of time in the life of the context, you referred to term T1
as (T1,Tx, isolate) (which shall be stored in your topology descriptor) , then
T1 and Tx are isolated for this command also......(if T1 did not get subtracted
after the topology settings because that would flush the topology for T1)

*) If at no point of time you referred to the pair (T1,Ty,..), then T1,Ty is
bothways for this command..............

But remember, you have to flush the topology descriptor for T1, if T1 gets
subtracted from the context...................

Njoy
Chanchal...........

Paul Hollis <[email-masked]> on 10/19/2000 04:17:51 PM

To:   Chanchal Hassija/HSS@HSS
cc:   [email-masked]

Subject:  Re: Topology

Hi Chanchal,

thanks for the reply. However, if you take each step as being done in one
command
at a time, then step 2 would isolate T1 and T2, which is OK. However, once step
3
is issued in the command with only (T3, T2, oneway) specified in the command,
then
according to the rule quoted below any other association not mentioned in the
command is set to bothway.

In other words you would  need to specify (T1, T2 isolate) and (T3, T2, oneway)
in
the one command to achieve what is shown.

Does this make sense or am I on the wrong track.

Regards Paul.

Chanchal Hassija wrote:

> Hello Paul,
>
> My reply is embedded and prefixed with Chan>
>
> I have a quick question about the topology description in H.248.
>
> The wording in the Topology Descriptor chapter says:
>
> "The default association when a termination is not mentioned in the Topology
> descriptor is bothway (if T3 is added to a context with T1 and T2 with
topology
> (T3,T1,oneway) it will be connected bothway to T2)."
>
> but in the example in the diagrams, at step 3 we apply the topology "T3, T2,
> oneway". I would assume that if we apply the above rule, then there should be
a
> bothway connection between T1 and T2.
>
> Chan> You need to read all the steps in sequence. Hence the two-way connection
> between T1 and T2 in step 1) was broken in step 2) by the command....
> (T1,T2,Isolate).....Hence it is not there in step 3)
>
> Njoy....
> Chanchal........

---

From: Paul Hollis <[email-masked]>
Date: Mon, 23 Oct 2000 10:57:05 +1100

Hi,

the point I was trying to make is that if you send down (T1,Tx,isolate) in one
transaction, and then in a later transaction you send down (T1,Ty,isolate),
according to the rule:

"The default association when a termination is not mentioned in the Topology
descriptor is bothway (if T3 is added to a context with T1 and T2 with topology
(T3,T1,oneway) it will be connected bothway to T2)."

this would imply that T1 and Tx would now be bothway again as it was not
specifically mentioned in the descriptor.

Regards Paul.