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Single Area OSPF Cheat Sheet by

Cheatsheet for Single Area OSPF Lab

Basic Config­uration Commands

Router­(co­nfig)# no ip domain­-lookup
disables dns lookup
Router­(co­nfig)# hostname R1
changes hostname
R1(con­fig)# enable secret class
sets password for privileged EXEC
R1(con­fig)# line console 0
changes to line config­uration mode
R1(con­fig­-line)# logging synchr­onous
configures logging synchr­onous (no messages interrupt input)
R1(con­fig­-line)# password cisco
sets console password (also for vty)
R1(con­fig­-line)# login
enables login (also for vty)
R1# copy run start
copies the runnin­g-c­onf­igu­ration to the startu­p-c­onf­igr­ation
These commands are to be executed for all Routers!

Show Commands

Router# show ip route
displays ip routing table
Router# show ip protocols
shows a summary of configured routing protocol inform­ation
Router# show ip ospf
displays general inform­ation of OSPF
Router# show ip ospf interface
displays OSPF inform­ation for the interfaces on the router
These commands can be used to verify and troubl­eshoot your config­ura­tion.


Topology for and (Troub­les­hoo­ting)

Router1 Commands

R1(con­fig)# router ospf 1
enables OSPF (process id = 1)
R1(con­fig­-ro­uter)# network 192.16­8.1.0 area 0
configures a network
R1(con­fig)# interface lo0
configures a loopback interface
R1(con­fig­-if)# ip address 255.25­5.2­55.255
sets the ip address of an interface
R1(con­fig­-ro­uter)# router-id 11.11.1­1.11
sets the router id (ospf)
R1(con­fig­-ro­uter)# auto-cost refere­nce­-ba­ndwidth 10000
changes default reference bandwith
R1(con­fig­-if)# bandwidth 128
sets bandwidth of an interface
R1(con­fig­-if)# ip ospf cost 1565
manually sets cost of a link

Router2 Commands

R2(con­fig­-ro­uter)# no passiv­e-i­nte­rface s0/0/0
removes passive status. router will receive OSPF routing updates.
Except the command(s) above, Router 2 mainly used the same commands as Router 1.

Router3 Commands

Router­3#clear ip ospf process
Clears all ospf processes
Except the command(s) above, Router 3 mainly used the same commands as Router 1.


Topology for

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