router ospf

8/6/2019 Router Ospf

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STEPS TO CONFIGURE OSPF ROUTING

Erasing and reloading the router

Router>enableRouter#erase startup-configRouter(config)#reload

router ospfprocess-idTo enable OSPF on a router

r1(config)#router ospf 1

network network-address wildcard-mask area area-id

R1(config-router)#network 192.168.1.128 0.0.0.63 area 0R1(config-router)#network 192.168.15.0 0.0.0.3 area 0R1(config-router)#end

B1(config)#router ospf 1B1(config-router)#network 192.168.0.0 0.0.0.255 area 0B1(config-router)#network 192.168.15.0 0.0.0.3 area 0B1(config-router)#end

Are there any router interfaces that do not need to have OSPF updates sent out?

R1 (config)# router ospf 1

R1 (config-router)#passive-interface FastEthernet0/0

bandwidth bandwidth-kbps

Router(config)# interface serial 0/0/0

Router(config-if)# bandwidth 64

Router(config)# interface serial 0/0/1

Router(config-if)# bandwidth 128

Alternate method tobandwidth-kbps, is ip ospf cost to directly config cost

R3(config)#interface serial0/0/0

R3(config-if)#ip ospf cost 1562

R3(config-if)#interface serial0/0/1

R3(config-if)#ip ospf cost 1562

The router connected to ISP called an autonomous system border router

Requires the use of the default-information originate command to propagate it

R1(config)#ip route 0.0.0.0 0.0.0.0 serial 0/0/0(loopback or serial exit interface)

R1(config)#router ospf 1

R1(config-router)#default-information originateR1(config-router)#

In order to establish adjacenices with neighbors, the following must be identical:

Network Type, Hello Interval, Dead Interval, Area ID

Manually modifying Hello & Dead intervals

ip ospf hello-interval seconds

ip ospf dead-interval seconds

R2(config)#interface serial0/0/0

R2(config-if)#ip ospf hello-interval 5


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R2(config-if)#ip ospf dead-interval 20

Use the auto-cost reference-bandwidth command to adjust the reference bandwidth value.

Increase the reference bandwidth to 10000 to simulate 10GigE speed.

Make sure reference bandwidth is the same on all routers.

R1(config-router)#auto-cost reference-bandwidth 10000

R2(config-router)#auto-cost reference-bandwidth 10000

R3(config-router)#auto-cost reference-bandwidth 10000Commands used to verify current router ID:

Show ip protocols Displays process ID, router ID, networks router is Advertising(receiving updates from) & administrative distance (110 for ospf)

Show ip ospf Displays process ID, router ID, area info. & the last time SPFalgorithm calculated

Show ip ospf interface Displays hello interval and dead interval

show ip ospf neighbor used to verify and troubleshoot neighbor relationships

show interface display bandwidth, most serial link default to 1.544 Mbps

show ip route view routing table, quickest way to verify confergence

To turn off OSPF, use the following command. Router(config)#no router ospfprocess-id

Use the OSPF Priority to Determine the DR and BDR

Use the ip ospf priority interface command to change the OSPF priority of router to 255.

This is the highest possible priority.

R1(config)#interface fastEthernet0/0

R1(config-if)#ip ospf priority 255

R1(config-if)#end

Use the ip ospf priority interface command to change the OSPF priority of R3 to 100.



R3(config-if)#end

Use the ip ospf priority interface command to change the priority of R2 router to 0

A priority of 0 causes the router to be ineligible to participate and

DR or BDR.



R2(config-if)#end

Shut down and re-enable the FastEthernet0/0 interfaces to force an OSPF election.

The FastEthernet0/0 interfaces of each of the routers can be shut down and re-enabled to

force an OSPF election. Shut down the FastEthernet0/0 interface on each

hree routers. Notice that as the interfaces are shut down the OSPF

ies are lost.


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You are not required to alter any of these parameters, but some interface parameters mustbe consistent across all routers in an attached network.

In interface configuration mode,specify any of the following: Command

Purpose

ip ospf cost cost Explicitly specify the cost of sending a packet on aOSPF interface.

ip ospf retransmit-interval seconds Specify the number of seconds between link stateadvertisement retransmissions for adjacenciesbelonging to an OSPF interface.

ip ospf transmit-delay seconds Set the estimated number of seconds it takes totransmit a link state update packet on an OSPFinterface.

ip ospf priority number Set router priority to help determine the OSPFdesignated router for a network.

ip ospf hello-interval seconds Specify the length of time, in seconds, between thhello packets that a router sends on an OSPFinterface.

ip ospf dead-interval seconds Set the number of seconds that a routers hellopackets must not have been seen before itsneighbors declare the OSPF router down.

ip ospf authentication-keypassword

Assign a specific password to be used byneighboring OSPF routers on a network segmentthat is using OSPFs simple passwordauthentication.

router ospf

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