Policy Aware Switching

Firstly, I'm going to be out of class on Tuesday. I hope you guys have a good talk.

I couldn't finish it, 26 pages for something I've listened to numerous talks about. It's quite likely I've missed some details, but the idea is pretty simple:

Overlays give us a few advantages, one of which is in routing. We use that in this in the PAS to enforce routes that packets must fly by to reach their endpoint. For instance, we can enforce, in the overlay alone, that a packet must go through a firewall before hitting me.

This gives huge flexibility, all the flexibility you'd expect an overlay to allow. In my nascent graduate career, I first worked on a project that lined up very well with this. PAS gives you various abilities. You can do statistical tricks, allowing packets through some time, for active testing or load balancing.

It has one huge problem though, which is something I've talked about a few times on this blog. It's not optimizing for the common case. They want performance, and this doesn't increase it. For top-tier datacenter companies such as Google, this is totally useless. They'd much rather pay their network engineers a larger amount and get better utilization. It does make sense for smaller datacenters, but not really, as they have fewer configuration problems. Lastly, the engineers themselves are not likely to adopt technology that reduces their employment.

So this is neat work, and with it you can do some really cool things with a network. It's not targeted correctly. I can think of some good uses for this, mostly from ISPs and the like who may want more direct control of their traffic. For instance, they'd like to push all P2P people over some thinner line. That's not as sexy (or well funded) as datacenters.