It is interesting to see how DC networking is evolving. It is also interesting to see the war between Edge vs Core. What I mean by Edge vs Core is whether the network intelligence should be at the edge or at the core. I must admit, the Edge seems to be winning over core. Let’s look at the choices we have:
1. Intelligent edge and simple core
2. Intelligent core and simple edge
In reality, the first option has fared well from scalability perspective. Internet is a perfect example of that.
Now let’s come back to the present day problem, virtualization and VM mobility. Do we need overlay networks with VXLAN/NVGRE/STT to solve those problems and thus create intelligent Edge or use EVB(802.1Qbg) and make the core more intelligent? Interestingly IBM has launched a virtual switch recently that supports EVB. But from the apathy of most of the vendors in implementing EVB, I am not sure whether it is gaining any tractions. While EVB can provide the right vlan to the right port with vm mobility, it doesn’t address some of the problems that overlay technologies are trying to solve, for example inadequate forwarding table sizes in switches and decoupling logical and physical configuration.
In my opinion, intelligent edge has many advantages. First of all it doesn’t need any forklift upgrades.By separating the logical topology from the underlying physical topology,the overlay technology can certainly make network more agile.