OSPFv2 for IPV4 LAN

Router Configuration

R1> enable / en

R1 # config terminal / conf t


Clock Rate to DCE Interface
Unit is in bps.

R1 (config) # int s0/0/0
R1 (config-if) # clock rate 128000


Bandwidth to Specific Interface
Unit is in kbps. Default for Serial is 1544 kbps that produces the Link Cost of 64.

R1 (config) # int s0/0/1
R1 (config-if) # bandwidth 128 or band 128


Default static route
Using Loopback 1 as exit interface, This is useful for simulating an Internet connection to ISP.
Usually passive-interface lo1 is recommended.

R1 (config) # ip route 0.0.0.0 0.0.0.0 lo1


Go to Router Configuration
Process ID = 1 (Note: Process ID is locally significant

R1 (config) # router ospf 1 / router os 1


Router ID 
(Note: Router ID is network significant that can affect Router Election)

R1 (config-router) # router-id 1.1.1.1


Network to be advertised OSPF
Advertising Link-State Updates (LSUs) within Backbone Area (Area 0)

R1 (config-router) # network 192.168.1.0 0.0.0.255 area 0 (for single-area in backbone area)

R1 (config-router) # network 192.168.2.0 0.0.0.255 area 1 (for multi-area)


Passive Interface (to prevent sending or receiving LSUs)

R1 (config-router) # passive-interface lo1 / pass lo1

or

R1 (config-router) # passive-interface default / pass def


Propagate and redistribute

R1 (config-router) # default-information originate / def orig


Auto-Cost Reference-Bandwidth
Unit is in Mbps. Default is 100 Mbps. Using 1 Gbps = 1000 Mbps as example.

R1 (config-router) # auto-cost reference-bandwidth 1000 / auto ref 1000


OSPF Cost to Specific Interface
Using serial 0/0/1 and 16000 as example.

R1 (config) # interface s0/0/1
R1 (config-if) # ip ospf cost 16000


OSPF Priority for DR, BDR and DROther to Specific Interface
(Default = 1 and Maximum = 255)

R1 (config) # interface g0/1
R1 (config-if) # ip ospf priority 100
R1 (config-if) # end

Note: Remember to adjust the priority for all other routers at specific interfaces.
Save all configurations. Then reload to ensure status change in DR, BDR and DROther for all routers.


Clear OSPF Process ID
R1 (config-router) # end
R1 # wr (Note: Always remember to save all your running config to startup config)
R1 # ip clear ospf 1 process

Then reload the startup config.

R1# reload