Posted on Monday, 23rd August 2004 by sean

In the last article about EIGRP, I’ll go over some of the show and debug commands relevant to the operation of EIGRP.

Show the established neighbours:

r0#show ip eigrp neighbors
IP-EIGRP neighbors for process 1
H   Address                 Interface   Hold Uptime   SRTT   RTO  Q  Seq Type
                                        (sec)         (ms)       Cnt Num
1   192.168.1.136           Et0           13 00:00:29  404  2424  0  18
0   192.168.1.93            Et0           13 00:00:29   12   200  0  26

Watch the uptime and sequence numbers… Low uptime and increasing sequence numbers mean flapping. If there is a problem establishing an adjacency, you’ll see the process “waiting for init ack” or something similar:

r0#show ip eigrp neighbors detail
IP-EIGRP neighbors for process 1
H   Address                 Interface   Hold Uptime   SRTT   RTO  Q  Seq Type
                                        (sec)         (ms)       Cnt Num
0   192.168.1.136           Et0           14 00:00:00    1  2000  1  0
   Last startup serial 2
   Version 12.2/1.2, Retrans: 0, Retries: 0, Waiting for Init, Waiting for Init Ack, reinit for 576 msec

To debug neighbor adjacency problems, debug eigrp packets hello:

r1#debug eigrp packets hello
EIGRP Packets debugging is on
    (HELLO)
11:39:21: EIGRP: Received HELLO on Serial0.101 nbr 172.18.0.2
11:39:21:   AS 1, Flags 0x0, Seq 0/0 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/0
11:39:21: EIGRP: Sending HELLO on Ethernet0
11:39:21:   AS 1, Flags 0x0, Seq 0/0 idbQ 0/0 iidbQ un/rely 0/0
11:39:22: EIGRP: Received HELLO on Ethernet0 nbr 192.168.1.93
11:39:22:   AS 1, Flags 0x0, Seq 0/0 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/0
11:39:24: EIGRP: Received HELLO on Ethernet0 nbr 192.168.1.134
11:39:24:   AS 1, Flags 0x0, Seq 0/0 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/1
11:39:24: EIGRP: Sending HELLO on Serial0.101
11:39:24:   AS 1, Flags 0x0, Seq 0/0 idbQ 0/0 iidbQ un/rely 0/0
11:39:26: EIGRP: Received HELLO on Serial0.101 nbr 172.18.0.2
11:39:26:   AS 1, Flags 0x0, Seq 0/0 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/0

As a note, there are debug commands under both “debug eigrp” and “debug ip eigrp”.

Showing the topology entries for a route helps to figure out the metric calculations, and why one route may be preferred over another one:

r1#show ip eigrp topology 10.0.1.0/24
IP-EIGRP (AS 1): Topology entry for 10.0.1.0/24
  State is Passive, Query origin flag is 1, 1 Successor(s), FD is 2313984
  Routing Descriptor Blocks:
  172.18.0.2 (Serial0.101), from 172.18.0.2, Send flag is 0x0
      Composite metric is (2313984/304128), Route is Internal
      Vector metric:
        Minimum bandwidth is 1544 Kbit
        Total delay is 25630 microseconds
        Reliability is 255/255
        Load is 1/255
        Minimum MTU is 1500
        Hop count is 2
  192.168.1.93 (Ethernet0), from 192.168.1.93, Send flag is 0x0
      Composite metric is (2339584/2313984), Route is Internal
      Vector metric:
        Minimum bandwidth is 1544 Kbit
        Total delay is 26630 microseconds
        Reliability is 255/255
        Load is 1/255
        Minimum MTU is 1500
        Hop count is 3

Those are the big ones… You can get into the details of the packets under debug eigrp packets, or debug eigrp fsm to troubleshoot SIA routes.

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