RE: FW: RFC 4666 M3UA

The placing of the ITP point code in the OPC of an  RCT is the vendor's
implementation.  It is not defined in the RFC how this should work.  It
was done this way to make M3UA and SUA work the same in this case (SUA
would have to have the RCT OPC=ITP since the AS does not have MTP3
equivalent).

For M3UA the ITP's job is to front end these management messages and
translate them to the appropriate ASP/AS management message.  So when
the 240-0-0 is congested, for example, the ITP will terminate the TFC
and send a SCON to 1-1-1.  One can argue we should place 1-1-1 in the
OPC of the RCT (since we know the DPC of the TFC) and one can argue it
should be the ITP OPC (since the ITP is supposed to front end SSNM for
SS7 for the ASP). 

Josh


________________________________

From: Ong, Lyndon [mailto:[email protected]] 
Sent: Wednesday, September 12, 2007 2:15 PM
To: [email protected]
Cc: [email protected]
Subject: [Sigtran] FW: RFC 4666 M3UA


Forwarding question to the main list for comments.

________________________________

From: [email protected] [mailto:[email protected]] 
Sent: Monday, September 10, 2007 1:50 PM
To: [email protected]; [email protected]; Ong, Lyndon
Subject: RFC 4666 M3UA



Ken,Javier,Lyndon,

I got your names from an inquiry to the IETF about the RFC 4666.
Recently I have been involved in some testing of SS7 congestion and it's
reaction from and IP network using M3UA. The SS7 physical connection
utilized two ITP's with BLinks to the SS7 network. It appears the ITP's
tested were not capable of transmitting the RCT ( Route Congestion Test)
message in response to the TFC ( Transfer Congestion) they received with
a proper Originating Point Code. The ITP responded to the TFC with a RCT
that contained it's own originating point code. The RCT should contain
the OPC of the node at the end of the trunks. This would be the IP
endpoint not the ITP. Further it appears there is no provision within
M3UA to facilitate IP endpoints to send a message to the ITP that would
generate a proper RCT.

If possible could you respond to my concerns.


1.	Do I understand the M3UA protocol in the belief there is no
workable RCT provision, or is there a provision that would enable the
ITP to reply to a received TFC with a RCT that has the originating point
code of the IP endpoint? 
2.	I notice the DAUD message contains an Information Parameter. Is
there an intent or possibility the DAUD message could trigger a RCT on
the SS7 side of the ITP with the correct OPC of the IP endpoint?


Kevin P. Spence
Verizon Communications
Network Specialist 
TSS ENET Essential Network Elements Team
972-615-8199 ext. 4907

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