Re: [Sigtran] M3UA: SCON: congestion condition never abates

["Brian F. G. Bidulock" <[e-mail]>]

David,

SCON(0) is a valid message indicating "No congestion" for networks
the implement multiple congestion levels.  SCON messages for
international method do not include a congestion level parameter.

In international networks, congestion abatement is signalled in
response to DAUD with a DAVA not preceded by a SCON.

There is an implementation note undef RFC4666/3.4.4 that indicates
that an M3UA may maintain a timer to control congestion notification
vality that will be useful in cases where the peer node fails to
indicate congestion abatement.

There is also a note undef RFC4666/4.5.3 ASP Auditing that states
that periodic DAUD should not be initiated in response to SCON(0)
(i.e. multiple congestion level network signalling congestion
abatement).

--brian

David Laight wrote:                                        (Tue, 23 Oct 2012 16:21:38)
>    I presume this is (supposed to be) M3UA?
> 
>    M3UA is an abstraction of the interface between MTP3 and its userparts
>    (typically SCCP and ISUP).
> 
>    This means that the `AS' box isn't running MTP3, so your descriptions
>    about routing are incorrect.
> 
> 
>    The M3UA SCON indication is telling the userpart that MTP3 received a
>    TFC for the route.
> 
>    This could be used by the userpart to reduce its traffic.
> 
>    There is no network message that indicates that congestion has ceased.
> 
>    IIRC M3UA also doesn't contain any such message.
> 
>    The `congestion level' will be 1, 2 or 3 in ansi networks, and always 0
>    in ITU networks.
> 
> 
>                    David
> 


-- 
Brian F. G. Bidulock
[e-mail]
http://www.openss7.org/