On Dec 15, 2009, at 9:32 AM, Jeroen van der Ham wrote:

On 14/12/2009 18:31, Evangelos Chaniotakis wrote:
To be the devil's advocate, this leads to a situation where, for
example, a single GOLE that provides different services (i.e.
lightpath and vlan and SDH with no translation/encapsulation/
multiplexing capabilities), will need to provide a separate "topology"
per service, since the optical switch is not "connected" to the
ethernet switch. Does that make sense? It looks unnecessarily complex
to me.

You mean a GOLE that has an optical switch that is in no way connected
to the ethernet switch, i.e. there is no cable running between them?

Then I'd say that they are actually two different GOLEs.

If we had the concept of a "connected subgraph" of a domain or
topology, that might help with things.. a network provider would
advertise a single topology object that would contain one or more of
these.

We have to break things down into manageable chunks somehow. This is one
that seemed most natural. I'm sure there are also examples of a single
topology that is provided by multiple providers.

For example, say someone has a switch with sonet ports and ethernet ports and that switch connects to two other nodes, one via ethernet and one via sonet. Is the implication that the node connected via ethernet can connected to the node connected by SONET? If not, is that a connected graph for these purposes, or are there two separate topologies (the SONET one and the Ethernet one)? Relatedly, if a topology is disjoint due to solely to switching capabilities instead of cabling, is that two separate topologies or a single topology?