Adaptive Routing - Link State Routing

Initially, all ARPANET links were the same speed (56Kbps), and so the routing metric was just hops. As diversity increased (some links became 230Kbps or 1.544Mbps) other metrics were required. In addition, the growing size of the network exposed the slow convergence of distance vector routing. A simple example:

Routers using link state routing periodically undertake 5 (easy to understand) steps:

1. Discover their neighbours' network addresses (send request packets, receive reply packets).
2. Measure the delay or cost to each of its neighbours (immediate delay, or queued delay?).
3. Construct link-state packets containing all just learnt.
4. Broadcast this packet to all neighbours (use a flooding variant to ensure quick propagation).
5. Compute the shortest path to each other router (perhaps using Dijkstra's shortest path algorithm).