Link state protocols (contd)
- Sequence numbers have a wrap-around problem => responsible for early ARPAnet crashes.
- Age field (similar to TTL) + Sequence number if handled correctly is usually sufficient
- Dijkstra’s (“Shortest Path First” (SPF)) algorithm:
- Assume that the following databases are present:
- Link state DB: latest LSP from each router
- PATH: (ID, path cost, forwarding direction) triples. Set of of nodes for which the best path’s cost & forwarding direction have been found
- TENTATIVE: (ID, path cost, forwarding direction)