Simple Redistribution Configuration

(Do not try to copy and paste the commands that I have written for your reference since some commands may not be suppored by your IOS. So, try to issue each and every commands manually.) Step 1: At first, we configure both the routing protocols as shown in the diagram. Make sure that you have configured specific prefix on R2 when advertising network into both protocols. Example: router eigrp 100 no auto-summary network 10.1.12.2 0.0.0.0 (0.0.0.0 indicates that you have particularly 10.1.12.2 matched and no other IP can participate in eigrp) Once you are done with the routing protocol configuration, configure each loopback as OSPF point-topoint network. Since OSPF treats the loopback network as a host route and advertises it as /32 network regardless of the actual prefix length of the network. So, to intact the prefix original, you have to define the interface as point-to-point. Example: On R3 interface range loopback0 ip ospf network point-to-point Step 2: As you are asked to configured two way redistribution for full network reachability, you can have very minimal configuration as part of the solution. When redistributing OSPF into EIGRP, you should define metric parameters which are compatible with EIGRP metric calculation because anything you redistribute into EIGRP will have infinite metric. If you redistribute any routing protocol into OSPF, all the routes will have the default metric of 20. So, here in this case we are going to redistribute EIGRP into OSPF which doesn’t require seed metric but if we want all the classess and classful network into OSPF, we should add “subnets” keyword along with the redistribution command. On R2 router ospf 1 redistribute eigrp 100 subnets router eigrp 100 redistribute ospf 1 metric 1500 100 1 255 1500 Step 3: In this particular task, you are asked to allow only the odd numbered routes to be installed into OSPF network. R2 is the border router and it doesn’t make sense if we filter any prefix to be installed into the routing table of R2. So here in this case, you will create an access-list on R3 and apply it under the OSPF subcommand mode with distribute-list, which only restricts any prefix to be installed into RIB, not in the OSPF database. On R3: access-list 1 permit 10.1.1.0 0.0.0.255 access-list 1 permit 10.1.3.0 0.0.0.255 access-list 1 permit 10.1.5.0 0.0.0.255 router ospf 1 distribute-list 1 in Step 4: Finally, you are asked to allow only the routes having prefix length greater than /25 to be installed into EIGRP domain. So, the only option we have is prefix-list, which can match the wild card bits and it has the capability of checking prefix-length too. We create a prefix-list and bind it into route-map which has two sequence number 10 and 20. Sequence number 10 is used to match and deny the network mentinoed in the prefix-list BLOCK. On R2: ip prefix-list BLOCK 10.0.0.0/8 ge 25 route-map FILTER deny 10 match ip address prefix-list BLOCK route-map FILTER permit 20 router eigrp 100 redistribute ospf 1 metric 1500 100 1 255 1500 route-map FILTER Verification commands for the lab: On R2: show ip protocols show run | sec router sh route-map sh ip prefix-list sh access-list On R1: sh ip route eigrp sh ip protocols On R3: show ip route ospf sh ip ospf database sh run | sec router ospf sh access-list Good luck ☺