Subject: [SIGTRAN] M2PA - Local Processor Outage

From: Hecht Martin <[email-masked]>
Date: Tue, 10 Feb 2004 16:00:05 -0500

To whomever is interested in answering this enquiry:

In Section 4.1.4 (draft 11) it states:

	While in a local processor outage (LPO) condition:

	   (c) M2PA SHOULD continue to transmit messages that have been sent
by its upper layer MTP3.

Further on it states:

	When the local processor outage condition ends,....

	M2PA SHALL NOT resume transmitting User Data messages until it has
received the Link Status Ready message.

So, I am trying to understand these two statements.

Does it mean:

a) That M2PA should transmit messages received from MTP3 prior to the LPO
indication. But not transmit messages from its MTP3 received after LPO,
until LPR (Processor Recovered).  Then, when the Ready is received to start
transmitting them.

or

b) That transmission continues throughout the LPO condition, but that when
M2PA sends the Processor Recovered Link Status Message it must suspend
transmission until the Ready is received from the peer.  At that time
transmission will resume.

or

c) Something else is meant.

Note:
In our implementation of SS7 MTP2 messages are not transmitted at all during
LPO.  The only reason MSUs would be pending transmission (on the Transmit
Buffer Queue) when the LPO started would be that the RTB was full and the
LPO indication came prior to being able to transmit those messages..

Thank you,
Martin Hecht

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From: "Brian F. G. Bidulock" <[email-masked]>
Date: Tue, 10 Feb 2004 15:36:40 -0700

Hecht,

Hecht Martin wrote:                                                                  (Tue, 10 Feb 2004 16:00:05)
> transmission will resume.

This one.  LSPR is sent in the data stream and no messages should be sent
after the LSPR until LSR is received (also in the data stream) and sequence
numbers sychronized.

Maybe we should have said more explicity that sending of data messages is
suppressed between sending of LSPR and reception of LSR.

> LPO indication came prior to being able to transmit those messages..

The point is that you SHOULD continue to send those messages in the TB after
the LPO condition, unlike Q.703 which blocks them in the TB because it must
send continuous SIPO.  So, it is recomended to send messages during LPO.

In addition (c) in 4.1.4 was meant to handle the case (in some implementations
where the data path and control path are independent) where there is a local
processor outage (control path), but M2PA continues to receive messages from
MTP3 (data path).

--brian

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