Here is a list of the most important OSPF features:
- link state routing protocol
- classless routing protocol
- supports VLSM (Variable Length Subnet Mask)
- converges fast
- uses the concept of areas
- uses multicast address for routing updates (224.0.0.5 and 224.0.0.6)
- sends partial routing updates
- supports only equal cost load balancing
- manual summarization can be done only on ABRs and ASBRs
- uses interface cost as a metric
- uses SPF algorithm to calculate the best paths
- open standard
- each router inside an area has the same topology table
- supports clear-text and MD5 authentication
