Configure OSPFv2 on Cisco IOS: From Single Area to Multi-Area
Working reference for OSPFv2 on Cisco IOS - the cost metric, hello/dead timers, the six LSA types, the five area types (Backbone, Normal, Stub, TSA, NSSA), router roles (ABR, ASBR, IR), basic configuration with both the network statement and ip ospf interface command, multi-area design, summarization at the ABR (area range vs summary-address), virtual links, MD5 authentication, the five verification commands, and the pitfalls (reference bandwidth mismatch, wildcard vs subnet mask, EXSTART MTU loops, implicit router-id changes).