Subject: [Sigtran] SIGTRAN - M2PA draft 10 - T7 timer at Busy End

From: "Franck Boesch" <[email-masked]>
Date: Wed, 24 Dec 2003 10:45:22 +0100

Hello,

M2PA Draft 10 says:

--------------------------------------------------------------------------------
4.2.1  Sending and receiving messages::
...
Because propagation delays in IP networks are more variable than in
traditional SS7 networks, a single T7 timer (excessive delay of
acknowledgement) as in MTP2 is inadequate. If any message is
unacknowledged after a period equal to the T7 value, the T7 timer
SHALL expire.

4.1.5 Level 2 Flow Control:
...
When the peer M2PA receives the first Link Status Busy message, it
SHALL start the Remote Congestion timer T6 if there are messages in
the retransmission buffer awaiting acknowledgement (i.e., T7 is
running).  In addition, M2PA SHALL stop the T7 timer if it is running.
Additional Link Status Busy messages received while T6 is running do
not cause T6 to be reset and do not cause T7 to be started.  Also,
while T6 is running, T7 SHALL NOT be started.

When the peer M2PA receives the Link Status Busy Ended message and T6
has not expired, it SHALL stop T6 if T6 is running and start T7 if
there are messages awaiting acknowledgement in the retransmission
buffer.
...
--------------------------------------------------------------------------------

My question is the following:

At the Busy End (Link Status Busy Ended message receive), we may have several messages transmitted but waiting for acknowledgement. These messages may have been transmitted at different times. How do we restart T7 for each message ?

Should I understand that at the beginning of the busy condition (Link Status Busy message receive), T7 should be "suspended" (if running) and then "resumed" at Busy End  (for all transmitted but not acknowledged messages)?

Thanks,

Franck Boesch.

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From: "Brian F. G. Bidulock" <[email-masked]>
Date: Wed, 24 Dec 2003 20:28:18 -0700

Franck,

T7 is never restarted.  It is only started or stopped (or expires).

Where it says start, read: "start for all outstanding messages".

Where it says stop, read: "stopped for all outstanding messages".

Where it says expires, read: "expires for any message".

--brian

Franck Boesch wrote:                                                                (Wed, 24 Dec 2003 10:45:22)

-- 
Brian F. G. Bidulock
[email-masked]
http://www.openss7.org/

---

From: "Franck Boesch" <[email-masked]>
Date: Fri, 26 Dec 2003 08:59:11 +0100

Brian,
The way I must implement T7 is clear know.
Thanks,
Franck.

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]On Behalf Of
Brian F. G. Bidulock
Sent: jeudi 25 decembre 2003 04:28
To: Franck Boesch
Cc: [email-masked]
Subject: Re: [Sigtran] SIGTRAN - M2PA draft 10 - T7 timer at Busy End

Franck,

--brian

-- 
Brian F. G. Bidulock
[email-masked]
http://www.openss7.org/