[Nml-wg] Definitions of Topology, Domain and Network

[Aaron Brown]

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.


A question still open is the definition of "connected"? Is it a literal connected graph, or does it mean connected such that folks could actually somehow make circuits to get from any point in the graph to any other point (ignoring how they know that reservations and the like can happen)?

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?

Cheers,
Aaron

Winter 2010 ESCC/Internet2 Joint Techs
Hosted by the University of Utah - Salt Lake City, UT
January 31 - February 4, 2010
http://events.internet2.edu/2010/jt-slc/

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