Two approaches to network control plane

Per-router control (traditional)
- Individual routing algorithm is installed in each and every router.
Logically centralized control (SDN)
- Remote controller computes and installs flow tables in routers.

Goal of routing protocols

The goal is to determine shortest path from host to destination through networks.
Two protocols:
- Link state
  - Is based on Dijkstra algorithm
  - Is global and a centralized algorithm
  - All nodes have information on the same network topology
- Distance vector
  - Is based on Bellman-ford algorithm (dynamic programming)
  - Is a decentralized algorithm

Project on distance vector algorithm routing: Routing Protocol Simulator.