NTAC Peering Working Group

[Michael H Lambert <>]

On 30 May 2013, at 11:09, Steven Wallace wrote:

> Not sure I agree. I think it's more likely that the packet takes the 
> intended path or it doesn't get to its destination. One can argue that not 
> getting to the destination is taking the unexpected path :-) 
> 
> SDN means moving away from things like shared fate (routing info is 
> in-band, so if the link fails I know not to use link) and network nodes 
> deciding how to forward a packet based on their view of the topology. This 
> may not be the best thing in a  WAN for certain applications.

And in a fully-evolved SDN network (whatever that means), can we guarantee 
that diagnostic packets follow the same path as data flows (or even that the 
data flows are packetized in the traditional sense)?  If we view the 
SDN-based network as just another layer-2.5 (or -2) substrate to run layer-3 
on top of, I don't think the problem is very interesting.

Michael