[Nsi-wg] UvA/TUD topology exchange proposal

[Henrik Thostrup Jensen]

On Fri, 19 Sep 2014, Diederik Vandevenne wrote:

> However, without going too much into detail, there are other ways to 
> handle these policies.
>
> One idea is to indicate for each SDP in the topology file that transit 
> is allowed, denied or restricted.

This is the wrong way to think about. No one does transit except if they 
are being paid to do it. The problem with the tree-model is that I can no 
longer see if I am doing transit or not. And the switching model of NML 
makes it very difficult for a network to describe it.

If NSI becomes a tool for bypassing transit rules, it WILL BE SHUT DOWN.

I am trying to prevent that. I really am.

> The point I want to make is that there are solutions for your (policy) 
> problems that can work with a system that uses NML topology files and 
> (tree based) control / signaling planes that are distinct from the data 
> plane.
>
> I totally agree with what Guy said during the last conference call: We 
> want to do something new.

New is not a goal in itself. I thought we are trying to provide a 
point-to-point service with certain qos charactaristicas, and possibility 
to integrate network services into applicatios.

> Why bother with NSI if you only want it to be a copy of BGP?

I don't think I have said that. I am trying to keep the pathfinding from 
breaking transit rules and link AUPs.

> As Guy said, NSI can be seen as a form of SDN where the network is a 
> resource that can be controlled by applications and end users (based on 
> a policy of course).

Asking for certin QoS parameters seem like a thing IP doesn't have.

> The usefulness of NSI would be limited if it would work in the same way 
> as BGP.

No, the path finding would just work as BGP.

> Also note that if the services offered through NSI and BGP are not the 
> same, the policies may also be very different. The limitations you see 
> now may not even apply.

The policies are not there because of BGP. BGP is there to enforce the 
policies. A new protocol does not magically bypass these. In fact, it will 
be scrutinized hard to see if it adheres to this.

But what exactly is so bad about BGP? It is extremely flexible protocol 
with a proven track record. Sure, it doesn't allow user-driven or 
complicated path finding. But that is it main feature. It allows control 
over the network. Networking infrastructure are shared resources, often 
serving millions of users. Not a playground for users to create loops and 
bypass policies in.

And I am not buying the "some users had a bad experience with chain mode" 
argument. This meant that their transit provider screwed up or they or the 
protocol could not specify their requirements.


     Best regards, Henrik

  Henrik Thostrup Jensen <htj at nordu.net>
  Software Developer, NORDUnet