Subject: Re: [Sigtran] M2PA Comment: Timers

From: [email-masked]
Date: Fri, 21 Jun 2002 14:42:29 -0400

Hello All,

I agree with Brian that M2PA needs a T7 timer (excess delay of ack).
As it stands now in M2PA v5, it is possible (in the absence of
continuous outbound traffic) for a transmitted message to sit on a
queue forever waiting for the peer to ack.

I am hoping that the next version of M2PA has the following timers
(matching Q.703 where possible):

       Q.703 definition                 M2PA definition
       ----------------                 ---------------
T1  -- alignment ready                  waiting for LSR (currently T3)
T2  -- not aligned                      waiting for LSA (currently T1)
T3  -- aligned                          n/a
T4  -- proving period                   proving period (currently T2)
T5  -- sending SIB                      LSB interval
T6  -- remote congestion                same
T7  -- excess delay in acknowledgement  same
T10 -- n/a                              LSR interval
T11 -- n/a                              LSPO interval

Note that the T1, T2, T3 meanings are not really the same between
Q.703 and M2PA. Perhaps rather than calling these M2PA timers by
those identifiers they should have new ones. I threw T10 and T11
in just to stir the pot some more.

Regards,

Jeff

---------------------- Forwarded by Jeffrey Craig/Raleigh/TEKELEC on
06/21/2002 02:24 PM ---------------------------

"Brian F. G. Bidulock" <[email-masked]>@ietf.org on 06/21/2002
01:14:40 PM

Please respond to [email-masked]

Sent by:  [email-masked]

To:   "Javier Pastor-Balbas (ECE)" <[email-masked]>
cc:   Andrew Booth <[email-masked]>, [email-masked]
Subject:  Re: [Sigtran] M2PA Comment: T7 Timer

Javier,

No. MTP uses T7 at to detect excessive delay of acknowledgement.
There is no common equivalent in SCTP.  The use of lifetimes was
considered, however, as lifetimes are implementation dependent
and not a requirement part of an SCTP implementation, the M2PA
protocol needs to address this in a consistent fashion.

The use of additional timers in M2PA was discussed and agreed on
the list.  I refer you to the previous threads on this matter.
It might also help you understand the function of these additional
timers if you look at draft-bidulock-sigtran-m2pa-test-01.txt

--brian

Javier Pastor-Balbas (ECE) wrote:                          (Fri, 21 Jun
2002 19:06:59)
> Hi Brian ,
>
> Would it be more consistent to use the transport layer for these issues
in
> the IP network?
>
> MTP2 uses T7 to get reliability because it is only the wire what is
below...
> We should adapt it to the IP architecture.
>
> I don't see any reasons to have T7 in M2PA if we use SCTP.
>

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

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