Subject: MPLS and Optical Networks

From: Richard Barnett <[email-masked]>
Date: Sat, 29 Jan 2000 23:26:27 -0500

It would seem that to be able to use a passive optical core (i.e. no O-E-O
conversions) as a scalable interconnect, it probably needs to exhibit the
following characteristics:

- Dynamic switching capability (i.e. data units such as packets and cells
are individually routed in the optical domain). This is likely to be optical
TDM but would ideally be based on packet/frame/cell header information.

- Wavelength interchange capability.

- Some form of optical switch forming an optical cross-connect.

Unfortunately, OTDM wavelength interchanging cross-connects are not going to
be available for a little while. In the absence of such devices, passive
optical networks will probably behave more like flexible leased lines that
could be used to interconnect host devices and routers/switches albeit with
known scalability issues. In this context, it may be that extending MPLS to
the enterprise would have considerable relevance as it would allow the
enterprise routers/switches to implement policy-based routing and then
choose the appropriate LSP for transit to the optical edge device. The
optical edge device could then map the LSP to the appropriate outgoing
lambda to cross the optical core to the target router/switch. These
router/switches are then themselves interconnected across the optical core
via LSPs to form a virtual network topology on top of the optical network.
The use of routers/switches in this way should solve the scalability issues
until such time as more capable optical cores can be deployed.

Richard.
-------------------------------------------------------------
Richard Barnett
VP of System Architecture, Sirocco Systems.
Tel: 203 269 9919 x 126  Fax: 203 269 8291
Email: [email-masked]