[Nsi-wg] Some topology stuff for Glif

[Jeroen van der Ham]

Hi,

On 30 Sep 2013, at 16:10, Henrik Thostrup Jensen <htj at nordu.net> wrote:
> There is no bandwdith/capacity attribute in NML. This means we cannot do capacity matching in pathfinding Is this something we need? (insert usual disclaimer about advertised bandwidth being different from avaible)

That should be a good thing for the NSI Extension to add because there it is used in a much stricter context, i.e. service being announced as available (sometimes).

> NML does not have anything to denote available service definitions - per network or port. This again, makes pathfinding rather tricky and full of assumptions. While one can match labels with labels used in a service definition, there might be certain semantics which is not supported. Is this something we need to add?

What exactly do you mean? This is different from the SwitchingService that I described earlier?

> The NML model is quite different from the original network+port model of NSI. The role of a topology corresponds roughly to a network, but this is a restriction/policy that we have made (which I am perfectly fine with, but we just need to be explicit about this). This also means the way NML and NSI reference ports are different. In NSI we use a network id (which maps to a topology in NML) and a local id which maps to a fully qualified port name in NML, like this:
> 
> <sourceSTP>
>    <networkId>urn:ogf:network:aruba.net</networkId>
>    <localId>urn:ogf:network:aruba.net:ps</localId>
> </sourceSTP>
> 
> In NML, one can reference ports directly, like this:
> 
> <nml:PortGroup id="urn:ogf:network:bonaire.net:bonaire.net:arb-in" />
> 
> There is something to be said for both models, but not really about having both at the same. The network id in NSI is really redundant. I talked to to John about this in Madrid, and while he agreed he just couldn't get himself to remove (and I agree with this, the whole thing just feels so goddamn clumsy). Right now we essentially have 1½ topology model. There are some ways

yes ?

We're still using a somewhat "simple" topology where we have an explicit split between aggregator NSAs and NSAs taking care of a single network. If we ever move to a different kind of model, you need to have both an identifier for the NSA (i.e. network) and the specific Port that you want to get at.
And also given that URIs should not be interpreted (according to the RFCs and GFDs), we need to have separate ones.
 
> Then there are some security aspects. How do I control that no one injects services / topologies / servies into the topology? In OpenNSA, I do the following in the configuration:

That makes some sense indeed. We have to look at that more closely if we want to continue this model.

Jeroen.