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Troubleshooting Enhanced Interior Gateway Routing Protocol (EIGRP)

The basic command for checking the status and the start of troubleshooting of Enhanced Interior Gateway Routing Protocol (EIGRP) and other routing protocols is show ip protocols. The following output shows the output related to EIGRP. However, first here are some key things to look for:

  • No filters on interfaces, either incoming or outgoing

  • Metric settings (automatically at the default settings)

  • Maximum configured hop count

  • AS number

  • Summarization settings

  • Networks this router is distributing

  • Neighbors seen

  • Administrative distance

Router2>enable
Password:
Router2#show ip protocols
Routing Protocol is "eigrp 100"
  Outgoing update filter list for all interfaces is not set
  Incoming update filter list for all interfaces is not set
  Default networks flagged in outgoing updates
  Default networks accepted from incoming updates
  EIGRP metric weight K1=1, K2=0, K3=1, K4=0, K5=0
  EIGRP maximum hopcount 100
  EIGRP maximum metric variance 1
  Redistributing: eigrp 100
  EIGRP NSF-aware route hold timer is 240s
  Automatic network summarization is not in effect
  Maximum path: 4
  Routing for Networks:
    192.168.1.0
    192.168.5.0
  Routing Information Sources:
    Gateway         Distance      Last Update
    192.168.1.1           90      00:03:43
  Distance: internal 90 external 170

In addition to the basics found in show ip protocols, a suite of commands is available through the show ip eigrp command. The following information shows the categories of information you can find by using the show ip eigrp command:

Router2>enable
Password:
Router2#show ip eigrp ?
  <1-65535>   Autonomous System
  interfaces  IP-EIGRP interfaces
  neighbors   IP-EIGRP neighbors
  topology    IP-EIGRP Topology Table
  traffic     IP-EIGRP Traffic Statistics
  vrf         Select a VPN Routing/Forwarding instance

The interfaces option

The interfaces option identifies which interfaces receive EIGRP messages, and how many possible unreliable and reliable routes exist.

Router2>enable
Password:
Router2#show ip eigrp interfaces
IP-EIGRP interfaces for process 100
                        Xmit Queue   Mean   Pacing Time   Multicast    Pending
Interface        Peers  Un/Reliable  SRTT   Un/Reliable   Flow Timer   Routes
Fa0/0              1        0/0         4       0/10          50           0
Fa0/1              0        0/0         0       0/10           0           0

The neighbors option

The EIGRP neighbors option gives you information about systems from which your router is receiving EIGRP packets and when that information is allowed to be modified.

Router2>enable
Password:
Router2#show ip eigrp neighbors detail
IP-EIGRP neighbors for process 100
H   Address                 Interface       Hold Uptime   SRTT   RTO  Q  Seq
                                            (sec)         (ms)       Cnt Num
0   192.168.1.1             Fa0/0             11 00:02:02    4   200  0  10
   Version 12.0/1.0, Retrans: 1, Retries: 0

The topology option

The topology option displays information that goes into the topology table. In this case, you can see that the output includes a list of potential routes which can be used for the networks and on which interface the routes were learned. Notice that the listing includes successors, while if they were available, you would also see the feasible successors.

Router2>enable
Password:
Router2#show ip eigrp topology all
IP-EIGRP Topology Table for AS(100)/ID(192.168.5.1)
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
       r - reply Status, s - sia Status
P 192.168.10.0/24, 1 successors, FD is 284160, serno 7
        via 192.168.1.1 (284160/281600), FastEthernet0/0
P 192.168.1.0/24, 1 successors, FD is 28160, serno 6
        via Connected, FastEthernet0/0
P 192.168.5.0/24, 1 successors, FD is 28160, serno 8
        via Connected, FastEthernet0/1

The traffic option

A traffic display provides the statistics on the EIGRP traffic that your router is seeing, the packets it has received, and the number to which it has responded. Notice that these statistics are for a specific AS identifier.

Router2>enable
Password:
Router2#show ip eigrp traffic
IP-EIGRP Traffic Statistics for AS 100
  Hellos sent/received: 272/109
  Updates sent/received: 13/13
  Queries sent/received: 0/0
  Replies sent/received: 0/0
  Acks sent/received: 5/7
  Input queue high water mark 1, 0 drops
  SIA-Queries sent/received: 0/0
  SIA-Replies sent/received: 0/0
  Hello Process ID: 167
  PDM Process ID: 166

The debug command

Finally, you come to the debug command. Be aware that enabling any debug command puts a load on your router. Notice that the following output gives you information on the neighbors, such as new adjacency (learning of a new adjacent or neighbor router), changes in link availability, and routing information.

Router2>enable
Password:
Router2#debug ip eigrp
IP-EIGRP Route Events debugging is on
*Mar 18 00:38:35.281: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 100: Neighbor 192.168.1.1 (FastEthernet0/0) is up: new adjacency
*Mar 18 00:38:49.569: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 100: Neighbor 192.168.1.1 (FastEthernet0/0) is down: peer restarted
*Mar 18 00:38:54.321: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 100: Neighbor 192.168.1.1 (FastEthernet0/0) is up: new adjacency
*Mar 18 00:38:58.913: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 100: Neighbor 192.168.1.1 (FastEthernet0/0) is down: peer restarted
*Mar 18 00:39:03.397: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 100: Neighbor 192.168.1.1 (FastEthernet0/0) is up: new adjacency
*Mar 18 00:45:05.109: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 100: Neighbor 192.168.1.1 (FastEthernet0/0) is up: new adjacency
*Mar 18 00:45:05.117: IP-EIGRP(Default-IP-Routing-Table:100): 192.168.1.0/24 - do advertise out FastEthernet0/0
*Mar 18 00:45:05.697: IP-EIGRP(Default-IP-Routing-Table:100): Processing incoming UPDATE packet
*Mar 18 00:45:05.697: IP-EIGRP(Default-IP-Routing-Table:100): Int 192.168.10.0/24 M 284160 - 256000 28160 SM 281600 - 256000 25600
*Mar 18 00:45:05.713: %LINK-3-UPDOWN: Interface FastEthernet0/1, changed state to up
*Mar 18 00:45:05.717: IP-EIGRP(Default-IP-Routing-Table:100): Int 192.168.10.0/24 metric 284160 - 256000 28160
*Mar 18 00:45:06.713: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to up
*Mar 18 00:45:07.117: IP-EIGRP(Default-IP-Routing-Table:100): 192.168.1.0/24 - do advertise out FastEthernet0/0
*Mar 18 00:45:07.129: IP-EIGRP(Default-IP-Routing-Table:100): Int 192.168.10.0/24 metric 284160 - 256000 28160
*Mar 18 00:45:07.141: IP-EIGRP(Default-IP-Routing-Table:100): 192.168.5.0/24 - do advertise out FastEthernet0/0
*Mar 18 00:45:07.141: IP-EIGRP(Default-IP-Routing-Table:100): Int 192.168.5.0/24 metric 28160 - 25600 2560
*Mar 18 00:45:07.161: IP-EIGRP(Default-IP-Routing-Table:100): Processing incoming UPDATE packet
*Mar 18 00:45:07.161: IP-EIGRP(Default-IP-Routing-Table:100): Int 192.168.5.0/24 M 4294967295 - 256000 4294967295 SM 4294967295 - 256000 4294967295
Router2#no debug ip eigrp

If you have too many debug options enabled and the screen is overflowing with data, you can get the situation under control again by disabling all the options. Do this by typing u all to disable all possible debugging.

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