Subject: FW: SCON indicating ASP's congestion

From: "Sidebottom, Greg [BCNR:7M01:EXCH]" <[email-masked]>
Date: Tue, 3 Apr 2001 17:20:58 -0400

Resending ....

 -----Original Message-----
From: 	Sidebottom, Greg [BCNR:7M01:EXCH]  
Sent:	Tuesday, April 03, 2001 11:10 AM
To:	[email-masked]'; 'Kazuo Watanabe'
Subject:	RE: SCON indicating ASP's congestion

Greetings Kazuo-san,

Response below ...

 -----Original Message-----
From: 	Kazuo Watanabe [mailto:[email-masked]] 
Sent:	Thursday, March 29, 2001 7:56 AM
To:	[email-masked]
Subject:	SCON indicating ASP's congestion

In draft-06:
    Concerned Destination: 32-bits

       The optional Concerned Destination parameter is only used if the
       SCON is sent from an ASP to the SG. It contains the point code of
       the originator of the message that triggered the SCON. The Concerned
       Destination parameter contains one Concerned Destination Point Code
       field, a three-octet parameter to allow for 14-, 16- and 24-bit
       binary formatted SS7 Point Codes.  A Concerned Point Code that is
       less than 24-bits, is padded on the left to the 24-bit boundary. The
       SG sends a Transfer Controlled Message to the Concerned Point Code
       using the single Affected DPC contained in the SCON to populate the
       (affected) Destination field of the TFC message. Normally the
       Affected DPC will be equal to the point code of the ASP.

i read that paragraph as "ASP does/can determine the SPMC is now
encountering congestion."

i believe SG should determine SPMC's congestion and which PointCode
sending TFC to.

-- 
Kazuo Watanabe

[Greg] Yes, I agree with you on the principle that the SG determines whether
or not to send a TFC based on this event (reception of an SCON).  I think we
probably need a clarification here.  How about some text that says that "the
SG may decide whether to send a TFC to the SS7 network based on the overall
status of the SPMC, in order to comply with the congestion procedures of the
relevant MTP standard". 

I'm not sure that this makes a big difference because even the current
(national?) MTP procedures where an SS7 node sends a TFC based on internal
congestion are implementation dependent.   But it is probably wise for an SG
to look at the current SPMC congestion state in case the SPMC is already
congested - sending additional TFCs in this case could potentially cause
problems in the SS7 network.  This is because there are procedures in the
MTP for controlling the number of TFCs sent (See ITU Q.704 Section 11.2.3 to
see the ITU mechanism - TFC sent for every "n" messages or "N" octets
received for the congested destination).  MTP3-Users where the TFCs are
received may be sensitive to this.

Even if the SPMC is not currently congested when the SCON is received, the
SPMC may wish to suppress TFCs if there are too many SCONs - but I'm not
sure what "too many" is at this point  2:^(.

Cheers,

    Greg

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From: "Sidebottom, Greg [BCNR:7M01:EXCH]" <[email-masked]>
Date: Tue, 3 Apr 2001 17:20:58 -0400

Resending ....

 -----Original Message-----
From: 	Sidebottom, Greg [BCNR:7M01:EXCH]  
Sent:	Tuesday, April 03, 2001 11:10 AM
To:	[email-masked]'; 'Kazuo Watanabe'
Subject:	RE: SCON indicating ASP's congestion

Greetings Kazuo-san,

Response below ...

 -----Original Message-----
From: 	Kazuo Watanabe [mailto:[email-masked]] 
Sent:	Thursday, March 29, 2001 7:56 AM
To:	[email-masked]
Subject:	SCON indicating ASP's congestion

In draft-06:

-- 
Kazuo Watanabe

Cheers,

    Greg

---

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From: Kazuo Watanabe <[email-masked]>
Date: Wed, 04 Apr 2001 19:39:12 +0900

Hi Greg,

From: "Greg Sidebottom" <[email-masked]>
Subject: RE: SCON indicating ASP's congestion
Date: Tue, 3 Apr 2001 11:09:32 -0400
Message-ID: <[email-masked]>

> i believe SG should determine SPMC's congestion and which PointCode

sounds good.

BTW, what i wanted to say by 1st sentence was
"i don't think an ASP should be able to determine the SPMC's congestion."
and i would suggest Affected Destinations of SCON to be optional.

-- 
Kazuo Watanabe

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