Users Guide

Networks and Neighbors
As a link-state protocol, OSPF sends routing information to other OSPF routers concerning the state of the links between them.
The state (up or down) of those links is important.
Routers that share a link become neighbors on that segment. OSPF uses the Hello protocol as a neighbor discovery and keep
alive mechanism. After two routers are neighbors, they may proceed to exchange and synchronize their databases, which
creates an adjacency.
Router Types
Router types are attributes of the OSPF process.
A given physical router may be a part of one or more OSPF processes. For example, a router connected to more than one area,
receiving routing from a border gateway protocol (BGP) process connected to another AS acts as both an area border router
and an autonomous system router.
Each router has a unique ID, written in decimal format (A.B.C.D). You do not have to associate the router ID with a valid IP
address. However, to make troubleshooting easier, Dell EMC Networking recommends that the router ID and the router’s IP
address reflect each other.
The following example shows different router designations.
Figure 97. OSPF Routing Examples
Open Shortest Path First (OSPFv2 and OSPFv3)
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