OSPF is a classless, link-state routing protocol that maintains a database of topology information allowing routers to have full knowledge of distant routers. It load-balances across four equal metric paths by default and supports authentication. Troubleshooting OSPF involves checking neighbor adjacencies and routing tables.

1. © 2007 Cisco Systems, Inc. All rights reserved. ICND2 v1.0—4-1
Module Summary
 The routing algorithm of OSPF maintains a complex database of
topology information, which routers use to maintain full knowledge
of distant routers.
 OSPF is a classless, link-state routing protocol that is widely
deployed in many networks.
 OSPF load-balances across four equal metric paths by default on
Cisco routers.
 OSPF supports plaintext and MD5 authentication.
 There are several components to troubleshooting OSPF,
including OSPF neighbor adjacencies and routing tables.

2. © 2007 Cisco Systems, Inc. All rights reserved. ICND2 v1.0—4-2