Switch User Manual

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

5.1 27 August 2007