Redistribution from Network A to Network B

Using the network shown in Figure 14-6, Figure 14-7 demonstrates the redistribution of RIP routing information into the OSPF network. In this example, OSPF routing information is not redistributed to the RIP network. This would result in the end systems of the RIP network not being able to establish communications with end systems in the OSPF network. The end systems in the OSPF network, however, could establish communications with the end systems in the RIP network. Given that an IP-based communications session is inherently bidirectional, the RIP router would have to have a default

Internetworking with Dissimilar Protocols route configured so that response packets could be forwarded to the OSPF network.

Although such a situation may sound odd, it could be quite useful. In an extranet, for example, the two networks would belong to two different companies. Ostensibly, their business processes are interrelated, and they have linked their networks together to facilitate their mutual business. However, the administrators of the OSPF network might need to provide their user community with access to end systems, yet not want to compromise the security of their own network. In such cases, it might be necessary to add security mechanisms such as a firewall or even to use a router's access control list to prevent unwanted ingress.

A less glamorous possibility is that this configuration could be accidental. That is, the two networks should have established bidirectional route redistribution, but the OSPF network administrators may have neglected to configure their border gateway router to do so.

This one-way route redistribution is illustrated in Figure 14-7.

Figure 14-7: RIP routing information is redistributed to the OSPF network.

Figure 14-7: RIP routing information is redistributed to the OSPF network.

Server A.10 S^ivefaii
0 0

Post a comment