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Re: MPLS VPNs or not?

  • From: Robert Raszuk
  • Date: Tue Aug 07 12:02:58 2001


Ok so you say that increasing the number of features in any
implementation can cause critical bugs - hey I agree 100%. 

But what is the solution - do the freez in code and do not implement any
new features and enhancements ? All vendors (at least those significant
:) get a lot of new feature requests some of them touching much much
deeper then the mpls-vpn implementation into the elements of bgp, ospf,
isis etc .... Should all vendors just say - forget it we are not doing
it as it can introduce bugs ???

If not why you are particluary so flaming mpls-vpns and not other
features requested which when done wrong can cause hell lot of more
issues into the networks ?


> Vijay Gill wrote:
> --On Tuesday, August 07, 2001 08:29 -0700 Robert Raszuk <[email protected]>
> wrote:
> > Vijay,
> >
> > I am not defending IOS bugs or any particular implementation - I am
> > defending the architecture.
> >
> > R.
> Robert,
>  the point here being that software is a complex beast that is fairly hard
> to get right and often has very subtle failure modes. The interactions
> between various small bugs in subsystems often result in catastrophic
> failures when they interact as a part of a much larger whole. The
> architecture is fine, and in fact like all Powered By PowerPoint (tm)
> architectures, looks good in labs and papers, runs extremely well on slide
> projectors and will probably run fine in the real world for a while too.
> However, there are real life operations folks who have to run these things
> on large networks with lots of interactions among various components that
> are hard to duplicate in a lab setting (else we'd have bug free code on
> FCS).
> There was no singling out of IOS or any other implementation, I was just
> pointing out two fairly recent failure modes in code paths that has been
> exercised for years and deal with a "well known" RIB and adjacency
> maintenance issues. It is entirely possible that there are no bugs in
> current implementations; I just won't bet my day job on that possibility.
> > > Besides for those individuals who have problems with  maintaining a
> > > sinlge RIB with IGP routes I would higly advise a caution in deploying
> > > an mpls-vpn service or even touching the routers :).
> That was uncalled for. We do have problems maintaining a single RIB with
> IGP routes sometimes, mostly they are due to buggy implementations.
> /vijay