Re: M3UA: SCON: congestion condition never abates

Hi Urte

Even if AS does not send DAUD(for SG1 PC) to SG2, SG2 should send an SCON(Level-0) when the congestion clears.
In your case, you don't explain if the AS clears(for SG1) when SG2 sends SCON(Level-0) for SG1 PC.
The DAUD from AS is not as important as the SCON(Level-0) that should be sent by SG2 for clearing congestion towards SG1.
The congestion in your case is not abating because SG2 is never clearing congestion for PC:SG1.
This sounds normal scenario as per protocol.

Regards,
Satya



From: [email protected] [mailto:[email protected]] On Behalf Of urte plesske
Sent: 23 October 2012 15:58
To: [email protected]
Subject: [Sigtran] M3UA: SCON: congestion condition never abates

Hello, I'm faced with a problem based on the following architecture:

AS connected to two SGs
   AS
  /  \
 /    \
SG1---SG2
SCCP: SGs are making GTTs to route to the ss7 network.
MTP configurations on AS:
There are two routesets defined on AS, one to SG1 (containing direct route and route over SG2) and to SG2 (containing direct route and route over SG1)

SCON message was received by AS from SG2 with affected PC SG1.
On AS the route set (PC SG1) was inhibited. No traffic was sent to SG1 by AS any more.

Usually the AS would start sending periodic DAUDs messages as a result of the congestion, but because SG1 was got to know as adjacent node, no DAUDs with affected Point Code = Point Code SG1 were sent by any ASP.
No SCON messages were sent by SG2 to AS because no DATA and DAUD messages were received to react.
The congestion condition never abates.

Could you please help me with the following questions:
How to solve this situation (timer on AS?)?
Is it correct not to audit adjacent nodes?
Can (should) SG2 send a SCON message even there are no DATA and DAUD messages to react?
Where can I find (rfc) the information, that SCON is like TFC and not TFR?

Thanks a lot!

regards, urte

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