[Nml-wg] modelisation of the network description and dynamic circuits

[Freek Dijkstra]

John Vollbrecht wrote:

> 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 word *some* and *other* are important here: you are talking about
multiplexing multiple channels into a link. We haven't discussed that
yet. (I gladly do, but one thing at a time now).

I strongly disagree with this ad-hoc solution:

>           <link id="I2_host2_eth1_link" />
>           <vlanAvailability>400-800</vlanAvailability>

Because:
* the semantic is very technology specific. I rather see a more general 
model (in this case such as the label concept in GMPLS or multiplexing 
adaptation in G.805).
* the syntax is very ad-hoc. The power of XML is that you can compose 
properties of object in detail. Why use regexp syntax like "400-800" 
instead of <range><min>400</min><max>800</max></range>


> My question is how one describes a link as a set of VLANS

John, I'll write how we describe adaptations later. That first requires
a discussion on what a "layer" is (an OSI layer, technology, or sublayer
withing a technology). For now, please see e.g. the mail Jeroen sent to
the list recently about how adaptations are done in ITU-T G.805.

> 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" 

According to G.805, a link connection (= TE link above) can be made on a
server layer by terminating a network connection on a client layer.

Either we simply want to describe that TE link, or we want to describe
the terminated and adaptated network connection that creates the TE
link. Possibly we want a model were we can do both. How exactly this is
described is open. I guess we first need to discuss what a "path" is
(I'd say G.805 tandem connection) and what a link is (I'd say G.805 link
connection), and also what a layer is.

We haven't discussed these concepts so far. So feel free to step in and
make suggestions about classes and relations.

Regards,
Freek