RE: Recommendation for SUA modifications

Brian,

> -----Original Message-----
> From: [email protected] [mailto:[email protected]]On
> Behalf Of Brian F. G. Bidulock
> Sent: Wednesday, October 12, 2005 1:45 PM
> To: Haresign Lincoln
> Cc: [email protected]; [email protected]; [email protected]
> Subject: Re: [Sigtran] Recommendation for SUA modifications
>
>
> Lincoln,
>
> Please see comments inline.
>
> Haresign Lincoln wrote:                         (Wed, 12 Oct 2005
> 11:02:09)
>
> --X-snip-X--
> >
> >    Parameters
> >      Routing Context               Optional
> > |    Affected Point Code           Conditional *1
> >      SSN                           Optional *1
> >      Congestion Level              Mandatory
> >      SMI                           Optional
> >      Info String                   Optional
> >
> >
> > |  Note 1:    For an SCON from the SG to an ASP, when the SSN
> is included,
> >               the SCON message corresponds to the SCCP N-STATE
> primitive.
> >               When the SSN is not included, the SCON message corresponds
> >               to the SCCP N-PCSTATE primitive reporting signalling point
> >               or network congestion status.
> >
> > |             When the SCON is from the ASP to the SG, the
> affected point
> > |             code is an optional parameter.  The SG, if necessary, can
> > |             determine the affected PC from the Routing Context.
> >
> --X-snip-X--
>
> The SG cannot determine the PC of messages comming from the ASP by
> Routing Context.   If you think that it can, please detail one procedure
> that the SG can follow to associate a Point Code with this message when
> it is received from an ASP.
>
> Please bear in mind that an ASP is not restricted to sending messages
> from the source address that it has registered to receive messages.
> For example, if ASP A registers AS 1 with Routing key PC 111 and SSN 5,
> obtaining RC 1, it is permitted to send messages with source address
> PC 333 SSN 7 labelled with RC 1.  There is no restriction in the ASP->SG
> direction for SCON either.
[TOLGA]I have a different opinion here based on 4.3.4.3 ASP Active
Procedures section.
"The ASP SHOULD NOT send Data or SSNM
messages for the related Routing Context(s) before receiving an ASP
Active Ack message, or it will risk message loss."
I know it is not a "MUST NOT" but still it is nota good thing to do unless
one is aware of consequences and happy with them.
>
> So if the SG cannot get the OPC for the outgoing SS7 message from the
> SCON, where is it going to get it from?
>
> --X-snip-X--
> >
> >    Parameters
> >      Routing Context               Optional
> > |    Source Address                Optional *1
> > |    Affected Point Code           Conditional *1
> > |    SSN                           Conditional *1
> >      Congestion Level              Mandatory
> >      SMI                           Optional
> >      Info String                   Optional
> >
> >
> > |  Note 1:    For an SCON from the SG to an ASP, when the SSN
> is included,
> >               the SCON message corresponds to the SCCP N-STATE
> primitive.
> >               When the SSN is not included, the SCON message corresponds
> >               to the SCCP N-PCSTATE primitive reporting signalling point
> >               or network congestion status.
> >
> > |             When the SCON is from the ASP to the SG, the ASP can use
> > |             the source address parameter instead of the Affected Point
> > |             Code parameter.  This is used mainly in the case when the
> > |             Routing Keys associated with the ASP may not
> include a point
> > |             code and/or an SSN.  The SG should be able to
> derive the affected
> > |             PC from the registration information and take any actions
> > |             that might be appropriate to for subsystem congestion in
> > |             the network.
> > |
> > |             If the ASP is sending Source Address, it is not
> necessary to
> > |             send SSN and/or Affected Point Code as this information is
> > |             either contained in the source address, or can be
> derived at
> > |             the SG.
> >
>
>
> When developing the RFC we considered using Source Address in the SCON;
> however, as neither the N-STATE or N-PCSTATE can contain a Global Title,
> we rejected using the Source Address.  The situation has not changed.
>
> I strongly disagree with both proposals.  The motiviation behind them
> is to modify the SCON message to attempt something that it was never
> intended to do: communicate ASP congestion.  SCON is intended for SS7
> congestion only.
>
> If you want to develop enhancements for ASP congestion control, please
> write an extension draft detailing the new protocol elements required
> and their usage.  It might be easier to modify or participate in Kamesh's
> draft.
[TOLGA]I would think a new draft could be a better approach, if there is
consensus in the WG for it. I personally would like to see something like
ASPCONG etc...OTOH, if we don't define a new message, the need to know about
ASP congestion states does not disappear, and overloading SCON semantics
seem to be a practical approach. What do the others think, does a new draft
have a chance of survival?
>
> --brian
>
> --
> Brian F. G. Bidulock
> [email protected]
> http://www.openss7.org/
>
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