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Configure Portland router

Portland# configure terminal
Portland(config)# router ospf 1
Portland(config-router)# network area 1
Portland(config-router)# area 1 stub
Portland(config-router)# end
Portland#copy run start

Configure Indianapolis router

Indianapolis# configure terminal
Indianapolis(config)# router ospf 1
Indianapolis(config-router)# network area 1
Indianapolis(config-router)# area 1 stub no-summary
Indianapolis(config-router)# end
Indianapolis# copy run start


The tasks that needs to be configured are
Task1: Portland’s S 0/0 interface in Area 1
Task 2: Indianapolis’s S0/1 interface in Area 1
Task 3: Appropriate mask such that ONLY Portland S 0/0 and Indianapolis S 0/1
Could be in Area 1
Task4: Area 1 should not receive any external or inter-area routes (except the default route)

For task1 use the network command at ospf routing process mode on Portland router to advertise the network in Area 1.

Since task 3 requires we only use a mask that ONLY

Portland S 0/0 and Indianapolis S 0/1 belongs to Area 1.
Wild card mask needed to achieve above task3 is

Result network statement on Portland router for task1 and task3 will be

Portland(router-config)#network area 1

Similarly for Indianapolis router result network statement for task2 and task 3 will be

Indianapolis(router-config)#network area 1

Task 4 requires that Area 1 should not receive any external or inter-area routes
(Except the default route)

Configuring an area as a stub area forces its ABR (Area Border Router) to drop all external (type 5) routes and replaces them with a default route.
To limit routing information even more, an area can be made totally stubby using the
no-summary keyword on the ABR only. In that case, all interarea and external routes are dropped by the ABR and replaced by a default route.

For the above SIM Indianapolis router is ABR.

Configure area 1 on Portland router as stub area

Portland(config-router)#area 1 stub

Configure area 1 on Indianapolis as totally stubby area by using the keyword no-summary so that area 1 will not receive both external and inter-area routes except default route.

Indianapolis(config-router)# area 1 stub no-summary

By configuring the above two statements on respective routers we achieve task 4.

Important: To save running config to startup before exit.

Indianapolis #copy running-config startup-config

Portland# copy running-config startup-config

Verifying Configuration:

show ip ospf interface command shows the
interfaces on which OSPF runs and their current correct assigned area.

Use the command show ip route on Portland router
To check the type of ospf routes that is advertised into Portland from Indianapolis .


vicky said...

Thanks for your carefull and precise explain...Do you know if it´s allow to turn on, at the sim exam, the debug command? (debug ip ospf events)

Jammy said...

Hi....can you please guide for similar blogspot for CCNP- BCMSN paper.... I am preparing hardly and would like to see all hotspots for the same...

Muhammad said...

Good explanation to implement OSPF. More simulation should be added. One who are appearing the exam should send updates

veday001 said...

Another Good explaination.. God bless you..cheers

Ninad said...

Hello sir,
i have a doubt please help me out
If i type the following command will the configuration still work
on Portland router
Portland(config-router)# network area 1
and on router
& on Indianapolis router
Indianapolis(config-router)# network area 1

a3tips said...

Hi Nand,

Yes you can also use these commands for advertising networks into ospf on both routers.

But for good practise we need to use the subnet network address and its corresponding wild card mask for advertising ntws.

Hope this helps

Anonymous said...

Please Clarify: why do you use

instead of as was sated in the simlet

a3tips said...


Its the typo error . corrected the network statement