3Com Switch 8800 Advanced Software V5 Configuration Guide

Configuring OSPF Network Types 325
Prerequisites Before configuring an OSPF area, you have configured:
■ IP addresses for interfaces, making neighboring nodes accessible with each
other at network layer.
■ OSPF basic functions
Configuration Procedure To configure OSPF area parameters, use the following commands:
n
■ It is required to use the stub command on routers attached to a stub area.
■ It is required to use the nssa command on routers attached to an NSSA area.
■ Using the default-cost command only takes effect on the ABR of a stub area
or the ABR/ASBR of an NSSA area.
Configuring OSPF
Network Types
OSPF classifies networks into four types upon link layer protocols. Since an NBMA
network must be fully meshed, namely, any two routers in the network must have
a virtual link in between. In most cases, however, the requirement cannot be
satisfied, so you need to change the network type using commands.
For routers having no direct link in between, you can configure related interfaces
as the P2MP mode. If a router in the NBMA network has only a single peer, you
can also configure associated interfaces as the P2P mode.
In addition, when configuring broadcast and NBMA networks, you can specify for
interfaces DR priorities for DR/BDR election. In practice, routers having higher
reliability should become the DR/BDR.
To do... Use the command... Remarks
Enter system view system-view -
Enter OSPF view ospf [ process-id | router-id
router-id | vpn-instance
instance-name ] *
-
Enter area view area area-id Required
Configure the area as a stub
area
stub [ no-summary ] Optional
Not configured by default
Configure the area as an
NSSA area
nssa [
default-route-advertise |
no-import-route |
no-summary ] *
Optional
Not configured by default
Specify a cost for the default
route advertised to the stub
or NSSA area
default-cost cost Optional
Defaults to 1
Create and configure a
virtual link
vlink-peer router-id [ hello
seconds | retransmit seconds
| trans-delay seconds | dead
seconds | simple [ plain |
cipher ] password | { md5 |
hmac-md5 } key-id [ plain |
cipher ] password ] *
Optional
Configured on both ends of a
virtual link
Note that hello and dead
parameters must be identical
on both ends of the link
Configure and advertise a
host route
host-advertise ip-address
cost
Optional
Not advertised by default