Subject: Re: [Sigtran] Comment on M2PA - Slow Start

From: [email-masked]
Date: Mon, 22 Jul 2002 15:48:28 -0400

Brian and others,

Assuming turning off slow start is not an option, use of heart beat to keep
an idle association from going through slow start is the only thing that
can be done to reduce the impact on m2pa?
Also, is the conclusion that the impact of going through slow start during
changeover would be insignificant (assuming a properly engineering IP
network)?

Thanks
Ray

                    "Brian F. G.                                                                  
                    Bidulock"            To:     [email-masked]                             
                    <bidulock@ope        cc:     [email-masked], [email-masked],        
                    nss7.org>            [email-masked], (bcc: Ray P. Singh/Telcordia)    
                                         Subject:     Re: [Sigtran] Comment on M2PA - Slow Start  
                    07/22/02                                                                      
                    02:02 PM                                                                      
                    Please                                                                        
                    respond to                                                                    
                    bidulock                                                                      

Ray,

As slow start is performed by the sender and there is no protocol part
for congestion control (unless maybe you consider ECN), avoiding slow
start is implementation dependent (as is fairly stated in the AS).  If
you want to turn off your slow start or use the hearbeat mechanism to
keep an idle association out of slow start, your are welcome to try.  I
would be careful with the former (shutting off slow start) as the
congestion consequences could be disasterous.  Heartbeat is fairly safe,
but wasteful of bandwidth.  These are SCTP issues well outside the scope
of M2PA.  It was one of my original concerns with SS7 transport over
SCTP that SCTP could not make any guarantees whatsoever concerning the
timeliness of delivery of messages.  It is very difficult to set an
upper bound on the delay experienced by a message (slow start or not).

--brian

[email-masked] wrote:                 (Fri, 19 Jul 2002 18:52:44)
> Tom and others,
>
> Section 2.3.2.1 of m2pa draft 5 indicates that link status proving is
used
> to take SCTP through the slow start period.  However, the document does
not
> address how slow start would be addressed during changeover.  In the SS7
> environment traffic from the affected link is redistributed on the other
> links within a link set or combined link set during a changeover.
> Therefore, it is likely that SCTP slow-start will have adverse impacts on
> the volume of queued messages and link output delays. The Telephony
> applicability statement indicates that some telephony signaling
application
> may choose to relax the congestion control rules of SCTP.  However, the
> applicability document does not provide explicit guidance regarding how
> this is done.  This is an issue that needs to be addressed for m2pa.
>
> Regards
> Ray
>
>
>
>
> _______________________________________________
> Sigtran mailing list
> [email-masked]
> https://www1.ietf.org/mailman/listinfo/sigtran

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

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