This has been a great thread, and I would like to throw in a couple ideas about how DCN setup works or could work to get your ideas. First - There are a couple cases where the obvious way of describing a network doesn't work for DCN. Case 1 - We have a network with an ethernet interface to a switch. The switch is statically configured to take some VLANS to one endpoint and other VLANS to other networks. The way we have talked about handling this is to create a separate link for each VLAN group. I am not good at XML so I will write this as domain=Internet2 node=Boston-Ciena port = ethenet-A link = bu.edu domain=Internet2 node=Boston-Ciena port = ethenet-A link = tufts.edu Now in the properties (I think) for each link will be included the allowable VLANS. My question is how one describes a link as a set of VLANS Case 2 - Between I2-NY and GEANT-Paris we want to create multiple GE circuits which can be used to create connections between I2 and GEANT. One way to do this seems to be to create a "traffic engineering-link" between NY and Paris. The GE Ports are used when making a connection, and the points of the link have to determine which ports are available in much the same way that we determine which VLANS are available now. This seems to me to be equivalent to creating a "virtual" link between NY and Paris. I think Aaron said this would be possible (I may have misunderstood). If so I am wondering how this would be represented in the topology schema, and then how it is presented - presumably as a "view" or model to DCN. John