P. For a host on 50.50.50.0 to be able to route to a host on the 70.70.70.0 network, EIGRP routes will need to be redistributed into OSPF. Conversely, if hosts on the 70.70.70.0 network wish to talk with the hosts on 50.50.50.0, OSPF routes will need to be redistributed into EIGRP. Because there is only one router connecting these two domains together, redistribution must occur in both directions. OSPF 100 Area 0 EIGRP 100 Figure 11-5. Mutual redistribution Mutual Redistribution To accomplish mutual redistribution on one router, simply configure both protocols for redistribution into the other: router eigrp 100 redistribute ospf 100 network 20.20.20.0 0.0.0.255 default-metric 100000 100 255 1 1500 no auto-summary router ospf 100 redistribute eigrp 100 metric 100 subnets network 10.10.10.0 0.0.0.255 area 0 default-metric 10 The configuration is simple. I've followed the steps outlined in the preceding sections by establishing a default metric in each protocol, then redistributed accord- ingly. Nothing more needs to be done when there is only one router doing mutual redistribution. Redistribution Loops Redistribution can get interesting when there are multiple routers doing it. Routes redistributed from one routing protocol into another can be redistributed back into the originating protocol, which can cause some pretty strange results. All of the original metrics will have been lost, SO the route will inherit whatever metric was configured during redistribution. Figure 11-6 shows a network with three routers. R3 has a network attached that is being advertised in EIGRP 100 by way of the redistribute connected command (50.50. 50.0/24). R1 is redistributing from OSPF into EIGRP (from left to right in the draw- ing), and R2 is redistributing from EIGRP to OSPF (from right to left in the drawing). Redistribute connected OSPF 100 Area 0 EIGRP 100 Figure 11-6. Redistribution loop Chapter 11: Redistribution The network 50.50.50.0/24 will be advertised from R3 to R1 and R2 through EIGRP. R2 will in turn redistribute the ro