Cisco Ccnp Bsci Exam Tutorial Ospf Route Redistribution Review

Cisco Ccnp Bsci Exam Tutorial Ospf Route Redistribution Review



Cisco CCNP / BSCI Exam Tutorial: OSPF Route Redistribution Review
OSPF route redistribution is​ an​ important topic on the BSCI exam, and it's a​ topic full of​ details and defaults that you need to​ know for the exam room and the job .​
To help you pass the BSCI exam, here's a​ quick review of​ some of​ the OSPF route redistribution basics.
To see if​ a​ router is​ an​ ABR or​ ASBR, run show ip ospf .​
This also displays any routes being redistributed into OSPF on this router.
R1#show ip ospf
Routing Process ospf 1 with ID 1.1.1.1
Supports only single TOS(TOS0) routes
Supports opaque LSA
It is​ an​ area border and autonomous system boundary router
Redistributing External Routes from,
connected, includes subnets in​ redistribution
rip, includes subnets in​ redistribution
When redistributing RIP into OSPF, the subnets option is​ needed to​ include subnets in​ redistribution .​
When redistributing OSPF into RIP, a​ seed metric must be specified .​
(OSPF gives redistributed routes a​ default metric of​ 20 – this can be changed, but a​ seed metric does not have to​ be set.)
R1(config)#router ospf 1
R1(config-router)#redistribute connected
% Only classful networks will be redistributed
R1(config-router)#redistribute connected subnets
R1(config-router)#redistribute rip subnets
R1(config-router)#router rip
R1(config-router)#redistribute connected metric 1
R1(config-router)#redistribute ospf 1 metric 1
By default, routes redistributed into OSPF are marked as​ E2 routes .​
The metric for these routes reflects only the cost of​ the path from the ASBR to​ the destination network and does not include the cost of​ the path from the local router to​ the ASBR .​
By contrast, E1 routes include the cost of​ the entire path from the local router to​ the destination network.
O E2 5.1.1.1 [110/20] via 172.34.34.3, 00:33:21, Ethernet0
6.0.0.0/32 is​ subnetted, 1 subnets
O E2 6.1.1.1 [110/20] via 172.34.34.3, 00:33:21, Ethernet0
172.12.0.0/16 is​ variably subnetted, 2 subnets, 2 masks
O E2 172.12.21.0/30 [110/20] via 172.34.34.3, 00:33:32, Ethernet0
O E2 7.1.1.1 [110/20] via 172.34.34.3, 00:33:21, Ethernet0
15.0.0.0/24 is​ subnetted, 1 subnets
O E2 15.1.1.0 [110/20] via 172.34.34.3, 00:33:32, Ethernet0
To redistribute routes into OSPF and mark them as​ E1 upon redistribution, use the metric-type option with the redistribution command.
R1(config)#router ospf 1
R1(config-router)#redistribute rip subnets metric-type ?
1 Set OSPF External Type 1 metrics
2 Set OSPF External Type 2 metrics
R1(config-router)#redistribute rip subnets metric-type 1
Look at​ the same two routes in​ R4's routing table, which are now displayed as​ E1 routes:
O E1 5.1.1.1 [110/94] via 172.34.34.3, 00:04:13, Ethernet0
6.0.0.0/32 is​ subnetted, 1 subnets
O E1 6.1.1.1 [110/94] via 172.34.34.3, 00:04:14, Ethernet0
BSCI exam success and earning your CCNP certification depends on knowing the details, and there are plenty of​ details involved in​ OSPF route redistribution! Keep studying, practice different scenarios in​ your CCNA / CCNP home lab or​ rack rental, and you'll master these details and pass the exam!




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