Configuring The Router Id; Basic Ospf Topology - Enterasys C5G124-24 Configuration Manual

Basic OSPF Topology Configuration
1. See "Configuring OSPF
configuration. This basic configuration requires the configuration of four interfaces and associated
IP addresses. Also configured are two loopback interfaces, to use for the router IDs.

Configuring the Router ID

OSPF initially assigns all routers a router ID based on the highest loopback IP address of the
interfaces configured for IP routing. If there is no loopback interface configured then it will be the
highest VLAN IP address configured. This unique value, which is included in the hello packet
transmitted in Link State Advertisements (LSA), identifies one router to another and helps
establish adjacencies among OSPF routers. When you specify an interface as the router ID, this
value supersedes the default ID.
Example
Figure 22-1
Host 1
172.10.1.99/24
The following code example configures the basic OSPF topology as displayed in
above.
Router 1 CLI Input
Router 1(su)->router(Config)#interface vlan 1
Router 1(su)->router(Config-if(Vlan 1))#ip address 172.10.1.1 255.255.255.0
Router 1(su)->router(Config-if(Vlan 1))#ip ospf areaid 0.0.0.1
Router 1(su)->router(Config-if(Vlan 1))#ip ospf enable
Router 1(su)->router(Config-if(Vlan 1))#no shutdown
Router 1(su)->router(Config-if(Vlan 1))#exit
Router 1(su)->router(Config)#interface vlan 2
Router 1(su)->router(Config-if(Vlan 2))#ip address 172.10.2.1 255.255.255.0
Router 1(su)->router(Config-if(Vlan 2))#ip ospf areaid 0.0.0.1
Router 1(su)->router(Config-if(Vlan 2))#ip ospf enable
22-4 Configuring OSPFv2
Areas" on page 22-8 for additional discussion of OSPF area

Basic OSPF Topology

Area 1
Vlan 1
172.10.1.1/2 4 172.10.2.2/24
Vlan 2
172.10.2.1/24
Router 1
Vlan 2
Vlan 3
172.2.1.1/24
Router 2
Backbone
Area 0
Figure 22-1