OSPF and Eigrp Mutual Redistribution
Referring to the network in Figure 6-12, you can see in Example 6-46 that Router Cypher has no idea if any of the OSPF routes are possible via its connection to Router Tank.
Before
Example 6-46 Routing Table Before Mutual Redistribution
Cypher#show ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default U - per-user static route, o - ODR
Gateway of last resort is not set
64.0.0.0/30 is subnetted, 1 subnets C 64.246.202.0 is directly connected, Serial0
128.213.0.0/24 is subnetted, 4 subnets C 128.213.97.0 is directly connected, Loopback1
C 128.213.96.0 is directly connected, Loopback0
C 128.213.99.0 is directly connected, Loopback3
C 128.213.98.0 is directly connected, Loopback2
Cypher#
During
Example 6-47 shows how to configure redistribution on Router Tank. When this is combined with currently configured redistribution, you have achieved a state of mutual redistribution.
Example 6-47 Configuring Mutual Redistribution
Tank(config)#router eigrp 100
Tank(config-router)#redistribute ospf 100 metric ?
<1-4294967295> Bandwidth metric in Kbits per second
Tank(config-router)#redistribute ospf 100 metric 1500 ?
<0-4294967295> IGRP delay metric, in 10 microsecond units
Tank(config-router)#redistribute ospf 100 metric 1500 10 ?
<0-255> IGRP reliability metric where 255 is 100% reliable
Tank(config-router)#redistribute ospf 100 metric 1500 10 255 ?
<1-255> IGRP Effective bandwidth metric (Loading) where 255 is 100% loaded
Tank(config-router)#redistribute ospf 100 metric 1500 10 255 1 ?
<1-4294967295> IGRP MTU of the path
Tank(config-router)#redistribute ospf 100 metric 1500 10 255 1 1500
Tank(config-router)#
Having configured the metrics of the OSPF routes to equal the defaults of a serial line, you are ready to check if Router Cypher now knows about the OSPF routes.
After
The configuration was successful, and you can see in Example 6-48 that the routes are appearing as external EIGRP routes.
Example 6-48 Verifying That Redistribution Occurred
Cypher#show ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default U - per-user static route, o - ODR
Gateway of last resort is not set
10.0.0.0/24 is subnetted, 2 subnets D EX 10.10.10.0 [170/2221056] via 64.246.202.1, 00:00:10, Serial0 D EX 10.10.20.0 [170/2221056] via 64.246.202.1, 00:00:11, Serial0
64.0.0.0/30 is subnetted, 1 subnets C 64.246.202.0 is directly connected, Serial0
128.213.0.0/24 is subnetted, 4 subnets C 128.213.97.0 is directly connected, Loopback1
C 128.213.96.0 is directly connected, Loopback0
C 128.213.99.0 is directly connected, Loopback3
C 128.213.98.0 is directly connected, Loopback2
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D EX 192.168.252.0/24 [170/2221056] via 64.246.202.1, 00 D EX 192.168.253.0/24 [170/2221056] via 64.246.202.1, 00 D EX 192.168.254.0/24 [170/2221056] via 64.246.202.1, 00 |
00 00 00 |
11, Serial0 11, Serial0 11, Serial0 |
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Cypher# |
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So far in this example, you have not encountered a routing loop because the networks used are all different and because there are not many routes. However, in practice, such a problem is more likely to occur, and you should always use route maps to protect against routing loops. The next section discusses how to configure the route maps.
Continue reading here: Using Route Maps to Protect Against Routing Loops
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