[Nml-wg] Ports with multiple connections?
Jeroen van der Ham
vdham at uva.nl
Mon Aug 24 15:08:35 CDT 2009
Hello,
I have been examing some of the topologies of the IDC network at
Internet2 and others more closely and I have encountered some things
that we may want to look at.
One of the things that I would not know how to describe exactly in NML
is the following example:
A domain has a port on one of its devices. This port has an inter-domain
connection. Through this port there are two possible connections to
other domains, by means of separate VLAN labels. For example VLANs
1000-2000 go to one domain and 3000-4000 go to another.
There are different ways of solving this at the moment.
You do have to describe this somewhere as a single port, because of the
limitations on the capacity of this port. I came up with three possible
solutions, all with their own disadvantages:
- Describe a single port with two links attached to it.
This means breaks the assumption that a port can have at most one
bi-directional link attached to it.
- Describe a single port with two virtual ports each with its separate link.
This breaks the assumption that a port is always connected by a Link
(either a cross-connect or an external link), and we introduce a new
concept of a virtual port. Are there other cases that would warrant this
introduction?
- Describe a single port that is connected to a "virtual" node where the
connection is split into two.
This makes the description more complex, and also seems to allow a
direct connection between the two inter-domain connections without using
the original port.
Any other ideas?
Jeroen.
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