IP Routing Primer

Discontiguous Networks Using RIP and IGRP

In Figure 3-2, network 168.71.0.0 is no longer contiguous. It is separated by a serial link that has a different major network—168.72.0.0. This will cause both routers to summarize their subnets of 168.71.0.0 when sending advertisements. Summarization is explained in more detail later in this chapter.

Figure 3-2. Simplified network using different major network addresses.

For RIP, this means that neither router can reach the other's subnet of 168.71.0.0. The section on RIP that follows demonstrates this concept.

Note

For IGRP, the answer should have been the same as for RIP—neither router should ...