Re: Stepping back from the ASON Routing Discussion

["Adrian Farrel" <adrian@olddog.co.uk>]

Don,

Just picking out one snippet...

> >>Do we, or do we not need to support a physically separated
> >>architecture with a 1-n relationship between control plane
> >>and transport plane entities?
> >
> > I would say yes. The requirement I see here is devices not capable of
> > participating fully in GMPLS routing.

I had to read this several times before I got it. Sorry.

You mean that...
"It is a requirement of ASON routing to support networks that contain devices that do not
contain the capabilities to participate fully (or at all) in the routing protocols run
within the network."

That sounds a reasonable requirement.

There are two developments of this requirement.

The first is where the routing responsiblity for the device is taken on "by proxy" by a
control plane entity such as one that Lyndon, Jonathan and I have been drawing. In this
case, although the device is not participating in the routing protocols within the
network, it is fully represented and there are no issues (although we must ensure that
this function is covered by the requirements).

In the second case, ther are islands within the network which are simply not represented
to the routing protocol. This gives me a greater problem. Clearly you cannot route through
a part of the network unless it appears to be connected in the TEDB. In this case, I
suggest that what is needed is to represent those (legacy?) devices/subnetworks as
Forwarding Adjacencies or virtual TE links. This requires some advertisement by a control
plane entity on behalf of the devices/subnetworks, but does not expose the details of the
connectivity of the devices that do not support routing.

Some of you may (from time to time) hear me burble on about the fact that soft permanent
LSPs should not simply cover the case where the permanent part is at the edge of the
network. When I ramble in this way, I am talking about the second case, above.

Cheers,
Adrian