EIGRP can be configured to summarize routes, whether or not automatic summarization (auto-summary) is enabled. Because EIGRP is a classless routing protocol and includes the subnet mask in the routing updates, manual summarization can include supernet routes. Remember, a supernet is an aggregation of multiple major classful network addresses.

In Figure 1, two more networks are added to router R3 using loopback interfaces: and Although the loopback interfaces are virtual interfaces, they are used to represent physical networks for this example.

Figure 2 shows the commands on R3 to configure the two loopback interfaces and the configuration to enable both interfaces for EIGRP.

To verify that R3 sent EIGRP update packets to R1 and R2, the routing tables are examined on both routers.

In Figure 3, only the pertinent routes are shown. R1 and R2 routing tables show these additional networks in their routing tables: and Instead of sending three separate networks, R3 can summarize the,, and networks as a single route.