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

[Aaron Brown]

John Vollbrecht wrote:
> 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.
>   
So, the way I see this as being described would look similar to as follows:

<network id="I2">
    <!-- define a logical interface between NY and Paris -->
    <port id="I2_NY_to_GEANT-Paris">
        <composed-of>
            <!-- include references to the actual physical ports -->
            <port id="I2_host1_eth0" />
            <port id="I2_host2_eth1" />
        </composed-of>
    </port>

    <!-- define the physical interface/link from host1 in NY to Paris -->
    <node id="I2_host1">
        <port id="I2_host1_eth0">
           <link id="I2_host1_eth0_link" />
           <vlanAvailability>100-500</vlanAvailability>
        </port>
    </node>

    <!-- define the physical interface/link from host2 in NY to Paris -->
    <node id="I2_host2">
        <port id="I2_host2_eth1">
           <link id="I2_host2_eth1_link" />
           <vlanAvailability>400-800</vlanAvailability>
        </port>
    </node>

</network>

Then the path finding could happen using the logical interface or by
looking at the physical elements that can used to bring up the logical
link for the logical interface.

You could define a vlan link over a physical link similar to so using
virtual ports:

<node id="I2_host2">
    <!-- the physical port -->
    <port id="I2_host2_eth1">
        <link id="I2_host2_eth1_link" />
        <vlanAvailability>400-800</vlanAvailability>
    </port>

    <!-- the vlan 'portion' of that port -->
    <port id="I2_host2_eth1.400">
        <link id="I2_host2_eth1.400_link" />
        <vlan>400</vlan>
        <over>
            <port id="I2_host2_eth1" />
        </over>
    </port>
</node>

Another possibility would be to not have a virtual port and just include
the new link under the physical port:

<node id="I2_host2">
    <port id="I2_host2_eth1">
        <!-- the actual physical link -->
        <link id="I2_host2_eth1_link" />

        <!-- the vlan link -->
        <link id="I2_host2_eth1_vlan400">
             <vlan>400</vlan>
        </link>
        <vlanAvailability>400-800</vlanAvailability>
    </port>
</node>

I'm not sure which is the better way to do it. I like the virtual port
concept because it is more consistent with how all other 'virtual' ports
work (e.g. layer3 over layer2) and it allows us to easily describe the
capabilities of that port like we would any other port (bandwidth, etc).
It is, however, more verbose than just including the new link on the
physical port.

What does everyone else think?

Cheers,
Aaron