RE: M3UA notify message

Lincoln,

Yes, I figured that, but the case is still misleading. It tries to utilize
global-AS view as a tool for redundancy, where actually SCTP-multihoming
needs to be utilized. I don't think such a replacement is recommended,
considering that SCTP will provide failover without message loss and
missequencing.

    Thanks
    Tolga



> -----Original Message-----
> From: Haresign Lincoln [mailto:[email protected]]
> Sent: Friday, February 24, 2006 9:52 AM
> To: Tolga Asveren; [email protected]
> Subject: RE: [Sigtran] M3UA notify message
>
>
> Tolga,
>
> I agree with you that you would use multihoming in this case.  My guess
> is that Brian was trying to demonstrate a point relating to M3UA and the
> issues under discussion.
>
> Regards,
> Lincoln
>
> -----Original Message-----
> From: Tolga Asveren [mailto:[email protected]]
> Sent: Friday, February 24, 2006 9:24 AM
> To: [email protected]
> Subject: RE: [Sigtran] M3UA notify message
>
> Brian,
>
> > -----Original Message-----
> > From: Brian F. G. Bidulock [mailto:[email protected]]
> > Sent: Friday, February 24, 2006 2:59 AM
> > To: [email protected]
> > Cc: [email protected]; [email protected]
> > Subject: Re: [Sigtran] M3UA notify message
> >
> >
> > prabind.chaubey,
> >
> > I think that you understand the situation well now.
> >
> > Because AS state depends upon ASP state, it is really not possible to
> > coordinate AS state across multiple SGP without also coordinating ASP
> > state.  That is why I feel that Greg stated the situation well in
> > 1.4.1 when he said:
> >
> >   "Where an SG contains more than one SGP, the MTP3 routeset, SPMC and
> >    remote AS/ASP states of each SGP SHOULD be coordinated across all
> the
> >    SGPs.  Rerouting of traffic between the SGPs MAY also be
> supported."
> >
> > Also note that we never required that a full-mesh of SCTP associations
>
> > be formed between ASPs and SGPs.  And, certainly, as you illustrate
> > below, the failure of an association (or two) can reduce a full-mesh
> > to a sparse set of SCTP associations anyway.  A full mesh would likely
>
> > only be for network redundancy.  If I have 2 ASPs, 2 SGPs and 2
> > networks, the most efficient arrangement from a performance/failure
> > perspective would be as follows:
> >
> >   ASP1  -------network A------- SGP1
> >         \______network B______/
> >          ______network B_____/\
> >         /                      \
> >   ASP2  -------network A------- SGP2
> [TOLGA]No, this is not really how it should be done -it is not wrong,
> but one should be ready to face consequences with such a setup-. I would
> expect both networks to be used between each peer with SCTP multihoming.
> We discussed this several times  that SCTP multihoming with multiple
> networks is practically necessary for a carrier grade environment.
> >
> > In that way if only network A fails, each ASP is still connected to a
> > different SGP (for performance), and the same is true if only network
> > B fails.  If network B fails, the situation degrades to
> >
> >   ASP1  -------network A------- SGP1
> >
> >
> >   ASP2  -------network A------- SGP2
> [TOLGA]If SCTP multihoming is used properly, there won't be any
> isolation because each STP association would utilize both networkA and
> networkB.
> >
> > The ability of the system to operate, should not be adversely affected
>
> > by the loss off network B.  If the SG does not coordinate AS/ASP
> > state, in scenarios like the 2+k scenario you detail, the system will
> > not function to the same degree as that where AS/ASP state is
> > coordinated.  Good reason for the SHOULD.
> [TOLGA]If SCTP multihoming is used utilizing both networks, ability of
> the system is not affected at all when networkB fails.
>
>
>
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