Ronny Lam


Juniper: Decoding SDN

Whereas most articles about Software Defined Networking are focusing on the decoupling of the dataplane and controlplane of the network, Juniper is taking this a step further. They are actually adding something which I have been missing in all the other posts: the managementplane. And they go even further by defining a servicesplane.

Normally I would make the distinction between a centralized and a decentralized controlplane. Where, in Juniper’s example, I would call the controlplane centralized and the servicesplane decentralized. Juniper however is placing both these functions in the devices, but they added a centralized version of these functions allowing the decentralized network to sync with their central peers.

This sounds like kind of a hybrid model, but it actually makes sense. The internet built it’s resiliency on the decentralized intelligence. It is not known for the speed of convergence when things break, neither is it known for easy traffic engineering. But it almost always works, even when things fail. Building an internet on centralized controllers is taking a risk. Will they keep working and will they be reachable? The hybrid model takes the best of both worlds. Building a resilient network with a centralized controlplane, and servicesplane, for Juniper’s sake.