Re: M3UA notify message

Tolga,

I cannot agree with you or subscribe to the view that an
association will never fail simply because of multihoming.

--brian

Tolga Asveren wrote:                                                 (Fri, 24 Feb 2006 09:23:34)
> 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.
> 
> 
> 
> _______________________________________________
> Sigtran mailing list
> [email protected]
> https://www1.ietf.org/mailman/listinfo/sigtran

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