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Re: Optical Crossconnects and IP

  • From: Thomas P. Brisco
  • Date: Tue May 09 17:18:07 2000

	OWR (Optical Wavelength Routing - as I've seen it)

	If you've been a reader of things like IEEE Communications,
you'll have seen (over the last few months) some articles regarding
dynamic control of wavelength routes and routing, and
"appropriate" interfaces into IP for that.  I suspect that this will
see the same level of success that did ATM SVCs.  Even if you do
MPLS badly enough, you sort of have IP controlled VCs.  I just don't
see IP having enough (i.e. any) "downward hooks" to control the
media layer well at all.  At least MPLS is sort of a co-resident
control layer -- but then we have data/routing types working that
instead of Telco types.  I did DDN X.25 for a little while, and
wasn't going to fall for ATM SVCs so quickly ...
	Bizarrely enough, last fall IEEE Communications *did* have
an article comparing/contrasting SONET vs. ATM vs. IP convergence on
failure, and issues regarding the interaction of having all layers
attempting reestablishment simultaneously (though the author seemed
limited to knowing only RIP).  I can only assume that the fellow was
drummed out of the union for such heresy.
	Dynamic re-routing and/or recovery of wavelengths, but I do
not believe that it needs to interact with the IP layer at all (this
does not imply that it must not be aware of it).  Not everyone seems
to get the idea of layering protocols ...

							- TP

On Tue, 9 May 2000, Bora Akyol wrote:

> Date: Tue, 09 May 2000 13:41:41 -0700
> From: Bora Akyol <[email protected]>
> To: Tony Li <[email protected]>
> Cc: [email protected]
> Subject: Re: Optical Crossconnects and IP
> I agree that a more dynamic optical infrastructure allows an IP network to be
> established faster and better (in terms of flexibility), but I disagree with
> the point of view that expects routers to dynamically establish, modify and
> tear-down circuits to other routers on demand. First of all, the current (IGP)
> routing protocols don't have a clue on who they want to talk to, they talk to
> whoever is out there and answers their HELLOs. Secondly, we tried this before
> (ATM) and it did not work.
> The current ODSI work has the concept of dynamic provisioning completely
> upside down, IMHO.
> Bora
> Tony Li wrote:
> > >  PS I keep wondering why people keep reinventing virtual circuits.
> >
> > A key observation here is that the point of an optical cross connect is to
> > provide a real circuit, not a virtual one.
> >
> > An optical cross connect, functioning along with IP routing and an
> > intelligent traffic management system can be used to dynamically place
> > bandwidth where it is needed, when it is needed.  The optical plane
> > provides an active provisioning fabric, allowing the network to be more
> > efficient.  And a more efficient network makes for a more profitable ISP.
> >
> > I don't see optical cross connects as an opposition to IP technology.
> > Rather, it provides one of the key means of automating the network that is
> > sorely needed.  A much better question to ask is: can IP routing possibly
> > survive its projected growth curve without the enabling technology that a
> > flexible optical fabic provides?
> >
> > Yours in dissent,
> > Tony
> >
> > p.s. Just in case there's any confusion out there, I'm still the world's
> > biggest proponent of IP routing.  I just don't assume that we know
> > everything about networking already.  I hope that it can be made better.