The MPLS WG Archive

[John Drake <jdrake@calient.net>]

Bala,

I think that there's a big difference between the service interface offered
to a user (aka the front end) and the interface that a service device uses
to attach to the rest of the network (aka the back end).  There's no reason
why the back end couldn't be GMPLS in peer mode even if the front end was
something silly like ATM UNI.

Thanks,

John 

-----Original Message-----
From: Bala Rajagopalan [mailto:braja@tellium.com]
Sent: Thursday, October 19, 2000 9:42 AM
To: John Drake
Cc: 'darren.freeland@bt.com'; azinin@cisco.com; neil.2.harrison@bt.com;
mpls@UU.NET; ip-optical@lists.bell-labs.com
Subject: Re: [IP-Optical] RE: Optical link bundling. Was Re: Draft
MinutesFrom Pittsburgh


Hello,

John Drake wrote:

>
>
> For example, a few years ago, one would build an IP service using routers
> mesh connected in an overlay on top of a PNNI  transport network.  This
was
> perceived as an exquisitely painful way of doing things and led directly
to
> the development of MPLS.  I.e., extend the IP control plane to support
> traffic engineering and then have the ATM switches implement MPLS.  This
> eliminates the artificial overlay boundary between IP routers and ATM
> switches.  (On the other hand, there would still be operational benefits
to
> using MPLS to control the ATM switches even if the network owner wished to
> maintain this overlay boundary.)

In the case of IP over optical,
I would just like to add that once you do have an IP-centric control
plane within optical networks, you could have routing between IP and
optical network that in fact supports the overlay model, alleviating the
scalability concerns that arise with IP over ATM model described above.

It's then a question of the coupling between the IP and optical control
planes. This can be as loose or tight as you want, for example, supporting
a UNI that separates the control planes, or the peer model without any
separation.

I do agree that if  you considered other types of clients,  the
peer model constructs don't seem  practical.

regards,

--

Bala Rajagopalan
Tellium, Inc.
2 Crescent Place
P.O. Box 901
Oceanport, NJ 07757-0901
Tel: (732) 923-4237
Fax: (732) 923-9804
Email: braja@tellium.com