The MPLS WG Archive

[Curtis Villamizar <curtis@avici.com>]

In message <71DA16F18D32D2119A1D0000F8FE9A940920C211@mbtlipnt01.btlabs.bt.co.uk
>, darren.freeland@bt.com writes:
> I would support the view that having the router control the optical domain
> is not good.  This comes down to a simple desire to see an optical layer
> which is open to ALL clients - not just IP.  Of course it is possible to
> allow the router to control the optical layer ... however, this idea
> overlooks the fact that an operator may wish to carry many other clients
> across an optical network.
> 
> Regards,
> 
> Darren Freeland
> Networks Analyst
> BT Adastral Park
> 
> -----Original Message-----
> From: George Clapp [mailto:clapp@research.telcordia.com]
> ... 
> Could you give some examples of why it's not feasible?



Please refer to draft-kompella-mpls-optical-00.txt.

Consider the following example usage.

In the optical core, the optical switches acting as LSR would
advertise the available paths as FSC or LSC tunnels.  The LSR routers
adjacent to the optical core can create PSC over the FSC or LSC
tunnels.  These non-optical LSR will initially (and some people think
always) have no control over the routing of the FSC and LSC tunnels.

If there is a regional distribution of traffic, the core will be
attached to access routers.  This may be using LSC and/or TDM tunnels
again controlled by the optical switches acting as LSR.  The core and
access routers can create PSC to get from the core to the region.

End-to-end tunnels can take 3 hops, one through the near PSC from
access router to core, one through a PSC across the core, and the last
through the PSC across the far region to the destination access
router.

VPN tunnels are signaled via BGP.  These ride inside the e2e tunnels
but as currently implemented use LDP.  This implies that we ween the
VPN tunnels from LDP or do LDP inside the e2e tunnels.  This doesn't
scale as well as just having an RSVP-TE adjacency through the regional
PSC to the core.

Any type of traffic can run through this type of traffic engineered
network within the VPNs.  MPLS-TE provides a means to signal across
multiple optical domains of different type, without requiring all of
the LSR to know anything at all about how to router within any of the
optical domains themselves.

Curtis

ps- I'd be happy to contribute to the usage draft that is being split
out from draft-kompella-mpls-optical-00.txt.