IP routing 33

In this case, R4 in Area2 cannot be physically connected to Area0 (for some reason) and it will be connected to R3 which is NOT a backbone ABR (like R1 is for instance). As Area2 is not directly connected to backbone Area0 or directly connected to a backbone ABR router, clients from Area2 will not be able to access anything outside Area2. Also, router R3 is an ABR router connected to two non-backbone areas.

In order to solve these problems, virtual-link must be configured between router R3 and R1 which are both ABRs. Virtual-link cannot be configured on non-ABR routers.

Consider the following Router IDs:

R1 : 1.0.0.0

R3 : 3.0.1.0

R4 : 4.0.2.0

Virtual-link can be configured in two ways on ABR routers :

Configuring virtual link manually

Configuring virtual link automatically

The following is an example for creating an auto virtual link:

Creating auto virtual link

R1 (config-router)#auto-vlink

Example : 1 R1(config)#show ip ospf Router ID: 1.0.0.0 Admin Status: Enabled Version Number: 2

Area Border Router Oper Status: True

AS Boundary Router Config Status: False

External Link-State Advertisements: 0

External Link-State Checksum: 0(0x0)

Type-of-Service (TOS) Routing Supported: False

Originated Link-State Advertisements: 67

New Link-State Advertisements Received: 722

Nortel Ethernet Routing Switch 5500 Series

Configuration-IP Routing Protocols

NN47200-503 03.01 Standard

5.127 August 2007

Copyright © 2005-2007, Nortel Networks

Page 33
Image 33
Nortel Networks NN47200-503 manual Creating auto virtual link, R1 config-router#auto-vlink