Introduction; Terminology - Allied Telesis SwitchBlade x908 Series Software Reference Manual

OSPF Configuration

Introduction

This chapter contains basic OSPF configuration examples. To see details on the OSPF
commands used in these examples, or to see the outputs of the validation commands, refer to
Chapter 36, OSPF

Terminology

The following is a brief description of terms and concepts used to describe the OSPF protocol:
OSPF Router
Any Layer 3 routing device that is running OSPF, such as an Allied Telesis managed Layer 3
switch or Allied Telesis router.
Designated Router
Each OSPF network contains a designated router, that:
■
■
Since the topological database is spread over adjacencies, the designated router coordinates
the synchronization of the topological database on all the routers attached to the network.
The designated router for a broadcast network is determined dynamically via hello packets. On
non-broadcast multi-access networks, static configuration information is used to initiate the
search for a designated router. To help in dynamic fallover, OSPF also determines a backup
designated router for a network via hello packets. The backup designated router, like the
designated router maintains an adjacency to all other routers on the network. If the designated
router fails for any reason, the backup designated router takes over.
Autonomous System
A set of routers that exchange OSPF routing information with each other.
Router ID
A unique ID assigned to each OSPF router. This ID takes the same form as an IP address, i.e.
A.B.C.D, where each of A,B,C,D is a number between 0 and 254. This number uniquely
identifies the OSPF router within the AS.
Adjacency
A relationship created between neighboring OSPF routers, for the purpose of exchanging
topological information. Not every router needs to become adjacent to every other router.
Adjacencies are established and maintained with hello packets. These packets are sent
periodically on all router interfaces. Bidirectional communication is determined by a router
seeing itself listed in hello packets from its neighbors.
35.2
Commands.
originates the network link state advertisement for the network
becomes adjacent to all other routers on the network
Software Reference for SwitchBlade® x908, x900 and x600 Series Switches
TM
AlliedWare Plus Operating System - Software Version 5.3.1 C613-50007-01 REV B