245 C C D C C D D
10.1.3.0 10.1.2.0 10.1.1.0 10.1.7.0 10.1.6.0 10.1.5.0 10.1.4.0
is directly connected, Serial0/0/1 is directly connected, Serial0/0/0 [90/2172416] via 10.1.2.1, 00:00:09, Serial0/0/0 is directly connected, FastEthernet0/1 is directly connected, FastEthernet0/0 [90/2681856] via 10.1.2.1, 00:00:09, Serial0/0/0 [90/2681856] via 10.1.2.1, 00:00:09, Serial0/0/0
Now we have only one route to each remote network, and the 10.1.3.0 network is our backup link. Obviously, it would be better if we could use both links at the same time, but in my example, I made the 10.1.3.0 network a backup link. Let’s go back to the Corp router and see what it shows us in the neighbor table: Corp#sh ip eigrp neighbors IP-EIGRP neighbors for process 10 H Address Interface Hold Uptime SRTT (sec) (ms) Cnt Num 1 10.1.3.2 Se0/0/1 14 00:35:10 1 200 3 10.1.5.2 Se0/2/0 10 02:51:22 1 200 2 10.1.4.2 Se0/1/0 13 03:17:20 1 200 0 10.1.2.2 Se0/0/0 10 03:19:37 1 200
RTO Q Seq 0 0 0 0
81 31 20 80
We read the information in this output like this:
The H field indicates the order in which the neighbor was discovered. The hold time is how long this router will wait for a Hello packet to arrive from a specific neighbor. The uptime indicates how long the neighbor-ship has been established. The SRTT field is the smooth round-trip timer—an indication of the time it takes for a round-trip from this router to its neighbor and back. This value is used to determine how long to wait after a multicast for a reply from this neighbor. If a reply isn’t received in time, the router will switch to using unicasts in an attempt to complete the communication.
Now let’s see what’s in the Corp topology table by using the show ip eigrp topology command—this should be interesting! Corp#sh ip eigrp topology IP-EIGRP Topology Table for AS(10)/ID(10.1.5.1) Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply, r - reply Status, s - sia Status P 10.1.11.0/24, 1 successors, FD is 2172416 via 10.1.5.2 (2172416/28160), Serial0/2/0 P 10.1.10.0/24, 1 successors, FD is 2172416 via 10.1.5.2 (2195456/281600), Serial0/2/0 P 10.1.9.0/24, 1 successors, FD is 2195456 via 10.1.4.2 (2195456/281600), Serial0/1/0 P 10.1.8.0/24, 1 successors, FD is 2195456 via 10.1.4.2 (2195456/72960), Serial0/1/0