stem number (ASN). OSPF is more com- plicated to configure in this way, and is outside the realm of this book. OSPF on Cisco routers is configured with a process-ID, but this ID is locally significant to the router. Within a single router, routes between multiple OSPF processes are not automatically redistributed, but two OSPF routers, each with a different process-ID, will form a neighbor adjacency (assuming everything else required is in place). The process-ID in OSPF does not reference the domain. Figure 10-2 shows a network with two EIGRP processes active. Because the multicast packets sent by an EIGRP router will be destined for all EIGRP routers, all EIGRP routers will listen to the updates. The updates contain the autonomous-system-ID, SO the individual routers can determine whether to retain or discard them. RIP does not support the idea of separate processes, SO any router running RIP will receive and proc- ess updates from all other RIP routers on the network. When there are two autonomous systems on the same network, the routes learned in each may or may not be shared between the processes by default. One of the features of EIGRP is automatic redistribution between processes. For routes to be shared with other protocols, one of the routers must participate in both processes and be configured to share the routes between them. Communication Between Routers Router A Router B Router C EIGRP EIGRP Router D Router E Figure 10-2. Two EIGRP processes on a single network The act of passing routes from one process or routing protocol to another process or routing protocol is called redistribution. An example of multiple EIGRP routing pro- cesses being redistributed is shown in Figure 10-3. Router A Router B Router C EIGRP EIGRP Router D Router E Figure 10-3. Routing protocol redistribution In Figure 10-2, we have two EIGRP autonomous systems, but there is no way for the processes to learn each other's routes. In Figure 10-3, Router E is configured to be a member of EIGRP 100 and EIGRP 200. Router E thus redistri