The MPLS WG Archive

[Robert Raszuk <rraszuk@cisco.com>]

Eric,

> All of these things are things that exist and can be
> supported using ATM (for example).  Yet people you're
> talking to want them using MPLS.

That is true that all of them can be provisioned with ATM today. But the
problem is that using L2 (or any kind of tunneling) for TE, for VPN or
even for Circuit Transport scales very poorly. Once you provisioned
hundred or maybe thousand of VC your operations people are starting to
suffer from lack of control and maintenance nightmare. That from the
provider point of view.

>From the customer point of view things don't look nice either when he
needs to peer with hundreds of his own routers (the VPN case) rather
then with one (or two for redundancy) residing on his provider edge.

What MPLS gives you is the freedom to use L3 to deliver all of those
services without touching the underling L2. In fact you build your core
only once and don't need to modify it when customer is added/deleted or
when he requesting new service.

> Perhaps the unified control plane issue is not as orthogonal as you think?

As a matter of fact no later then last friday I was talking to large
telco shop which are deploying ATM + MPLS and they have cleary stated
that they want to run both PNNI + LDP. The reason being is that this ATM
backbone will be still serving the SVC/Soft-PVC connections while in the
same time be a mpsl aware transport for IP traffic.

R.

> Eric Gray wrote:
> 
> Robert,
> 
>         See in-line comment.
> 
> > -----Original Message-----
> > From: Robert Raszuk [mailto:rraszuk@cisco.com]
> > Sent: Tuesday, May 30, 2000 4:31 PM
> > To: David Charlap
> > Cc: mpls@UU.NET
> > Subject: Re: ATM Switches as LSR encoding techniques
> >
> >
> >
> > David,
> >
> > > want to?  If you've got ATM, use it.  One of the big points about using
> > > MPLS is to have one unified control plane - if you're going to run MPLS
> > > through an ATM network that doesn't participat in MPLS, then you've just
> >
> > I am talking daily to all major ISPs worldwide deploying MPLS and nobody
> > mentioned "unified control plane" as the reason to introduce MPLS into
> > their network. The major reason is to be able to use applications which
> > MPLS offers (Traffic Eng, MPLS-VPNs, Circuit Transport, Hierarchical
> > Routing etc ...)
> 
> This assertion sounds a little strange.
> 
> All of these things are things that exist and can be
> supported using ATM (for example).  Yet people you're
> talking to want them using MPLS.  Perhaps the unified
> control plane issue is not as orthogonal as you think?
> 
> >
> ...
> >
> > Robert.
> >
> >
> > ...
> > >
> > > -- David
> >