Subject: Re: [Sigtran] SG-SG communication draft

From: "vaibhav_madan" <[email-masked]>
Date: Sat, 04 May 2002 16:17:14 +0530

Hi

     I have a few questions on the TAL message:

Let us consider the situation in which a SG belongs to more than one network. When the SG comes up and it starts communication with the peer SGs, it will send a TAL message to all the peer SGs after the required SSNM messages has been exchanged. Now my question is -&gt; Can the SG send TAL for one network appearance when it comes up and for another network appearance at a later time(the case where the external management controls when to make an SG active for a particular network context)? In short, can we send a TAL even long after the SCTP association is established? If yes, then in Section 4.3 we need to add some description as to the cases in which TAL message can be sent - something like -

A TAL message will be exchanged between peer SGs as soon as the SG becomes ready to process traffic for  a particular network context(if it serves more than one network on the same SCTP Association) or as soon as the SCTP Association is established(if it serves only one network). 

Also is there a need to specify a timer as to how long an SG can wait before sending the TAL message.

Moreover, will the TAL message be sent by both the peer SGs to each other? If yes, then we can get into a condition in which one side sends a TAL message(saying that it is ready to process traffic) but the other side does not send a TAL(meaning that it is not ready to process traffic). So there will be one-way flow of data. Do both the SGs need to exchange TAL before message exchange can take place or one-way traffic is allowed?

Regards

Vaibhav

"Tolga Asveren" wrote:

I submitted the first version of SG-SG communciation draft yesterday. I
don't know, when it is going to be put to the database. So, please find
attached the draft.

Tolga

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From: "Tolga Asveren" <[email-masked]>
Date: Mon, 6 May 2002 09:06:19 -0400

Vaibhav,

Let us consider the situation in which a SG belongs to more than one
network. When the SG comes up and it starts communication with the peer SGs,
it will send a TAL message to all the peer SGs after the required SSNM
messages has been exchanged. Now my question is -> Can the SG send TAL for
one network appearance when it comes up and for another network appearance
at a later time(the case where the external management controls when to make
an SG active for a particular network context)? In short, can we send a TAL
even long after the SCTP association is established? If yes, then in Section
4.3 we need to add some description as to the cases in which TAL message can
be sent - something like -

A TAL message will be exchanged between peer SGs as soon as the SG becomes
ready to process traffic for  a particular network context(if it serves more
than one network on the same SCTP Association) or as soon as the SCTP
Association is established(if it serves only one network).

[TOLGA]  2.4 addresses this issue, although more explanation might be added.
The semantics of TAL is described in 2.4 and 4.3 , it is used to indicate
end of SSNM, which are used declare unavailable/restricted PCs. It is a
message per network. Initially I didn't think it as a message, which shows
that SG is ready to process traffic for a particular network. But by not
sending it for a network, one might use it for that purpose.

Also is there a need to specify a timer as to how long an SG can wait before
sending the TAL message.

[TOLGA] I think, we can live without a timer. We are using SCTP, and I think
it is a fair assumption that no message will be lost.

Moreover, will the TAL message be sent by both the peer SGs to each other?
If yes, then we can get into a condition in which one side sends a TAL
message(saying that it is ready to process traffic) but the other side does
not send a TAL(meaning that it is not ready to process traffic). So there
will be one-way flow of data. Do both the SGs need to exchange TAL before
message exchange can take place or one-way traffic is allowed?

[TOLGA] Both SGs will send it to each other. Currently I didn't put any
restrictions to prevent one-way flow of data. But as I mentioned before, the
idea was not to use TAL as a message, whihc shows readiness of SG. It just
shows that SSNM announcement after association establishment is done.