Congdon: Right. We're definitely pushing the envelope with the toolsets we have today. Visibility into what's going on is really difficult to obtain. That's one of the drivers behind this virtual-edge bridging that we've been working on, which is to enable better visibility into what's going on in the servers. For example, by using sFlow to give you that visibility, or embedded it into the switches themselves.
Then there's the scale of these tools. We're literally talking about millions of servers. The desire would be to put this all on one big VLAN, and then everything could move where it wants.
Another driver for why we want these big, flat Layer 2 networks is the convergence of Ethernet, taking over some of these protocols that were classically built on networks that were "Layer 2-ish," if you will; that is, non-routable, such as Fibre Channel over Ethernet (FCoE) and Infiniband.
The long term vision is, we want to get all this stuff running over Ethernet. The easiest way to scale to thousands of servers is to make the network big and flat. But big and flat is often a challenge. There are a number of things about Ethernet that prohibit that level of scaling. The traditional topology management protocols, like spanning trees, tend to not allow you to use all of the links. So you if have a big, flat network, that means we might not have the cross-sectional bandwidth we want for all of the nodes. So we need new topology management schemes.
The plug-and-play nature of Ethernet made it work real well. If you don't know where someone is, you flood the packet or broadcast to find somebody. Well, if you have 3 million people all chatting to figure out how to find an IP address, that can be pretty dramatic. So broadcast control becomes a challenge; we have to figure out how to make that work.
