BSCI - OSPF SIM

CCNP BSCI EXAM OSPF SIM QUESTION.

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Answer:
Configure Portland router

Portland# configure terminal
Portland(config)# router ospf 1
Portland(config-router)# network 192.168.5.4 0.0.0.3 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 192.165.5.4 0.0.0.3 area 1
Indianapolis(config-router)# area 1 stub no-summary
Indianapolis(config-router)# end
Indianapolis# copy run start

Explanation:

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 192.165.5.4 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 0.0.0.3

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

Portland(router-config)#network 192.165.5.4 0.0.0.3 area 1

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

Indianapolis(router-config)#network 192.165.5.4 0.0.0.3 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 .