3com 3031 Instruccion De Instalación

C

HAPTER

 40: OSPF C

ONFIGURATION

[Router B-ospf]area 0

[Router B-ospf-area-0.0.0.0]network 192.1.1.0 0.0.0.255 

In Router A, run 

 to view the OSPF peers. Please note that 

Router A has three peers.

All neighbors are in full state. This indicates that Router A forms neighboring 
relationships with all its neighbors (Router A and Router C must form neighboring 
relationships with all routers on the network so as to act on the DR and BDR on 
the network. Router A is the DR and Router C the BDR on the network. All other 
neighbors are DR other (this indicates that they are neither DR not BDR.)

Change the priority of Router B into 200:

[Router B-Ethernet1/0/0]ospf dr-priority 200

In router A, run 

 to view its OSPF peers. Please note the 

priority of Router B has been modified as 200, but it is still not the DR.

Only when the current DR is offline, will the DR be changed. Switch off Router A, 
and run 

display ospf peer 

command in Router D to view its peers. Please note 

the original BDR (Router C) becomes the DR, and Router B now becomes the BDR.

Switch off all the routers and restart them. Such operations will bring about a new 
DR/BDR selection. Router B will be elected as the DR (with a priority of 200), and 
Router A becomes the BDR (with a priority of 100).

In the following figure, Area 2 is not directly connected with Area 0. Area 1 serves 
as a transit area to connect Area 2 and Area 0. A virtual link is configured between 
Router B and Router C.

Figure 131   Networking diagram of OSPF virtual link

Virtual Link

1.1.1.1

2.2.2.2

3.3.3.3

Area 0

Area 2

Area 1

ethernet2/0/0

192.1.1.1/24

ethernet2/0/0

192.1.1.2/24

ethernet1/0/0

193.1.1.2/24

ethernet1/0/0

193.1.1.1/24

ethernet2/0/0

152.1.1.1/24

Router A

Router B

Router C