Cisco offers some useful tools for determining how EIGRP is working. Perhaps one of the best and most overlooked commands is show ip eigrp neighbors. This can be one of the most useful commands when verifying the operational status of EIGRP. The show ip eigrp neighbors command shows the status of all EIGRP neighbors. The neighbor should be "up" for as long as EIGRP has been running on the link. EIGRP forms a neighbor relationship with all routers on the same subnet and in the same AS.
EIGRP does not form a neighbor relationship with mismatched k values; however, a neighbor can be formed with mismatched hellos and dead timers.A neighbor with a short uptime is a clear indication of a problem. Another important field is the queue count. This field indicates the number of packets waiting to be transmitted to that neighbor. This value should be 0 or a number under 20.
Consistent Q values in the range of 60 or greater are considered high. A high SRTT number can mean that the packet isexperiencing some type of delay on the link
RTR1 #show ip eigrp neighbors
IP-EIGRP neighbors for process 2001
H Address Interface Hold Uptime SRTT RTO Q Seq
(sec) (ms) Cnt Num
1 172.16.1.5 Se0.1 136 05:48:23 36 1302 0 15
0 172.16.1.6 Se0.1 131 05:48:24 40 1302 0 17
RTR 1#
Handle (H)— A Cisco IOS internal number used to identify a neighbor. Do not confuse this with hop count.
Neighbor Address— The adjacent neighbor's IP address. A neighbor should be formed between every router on thatsubnet running EIGRP in a common AS.
Interface— The interface that is reporting the neighbor.
HoldTime— The amount of time, which counts down, that EIGRP waits for a hello before tearing down the neighbor.
Uptime— Statement of how long the neighbor has been up. This number should be up for as long as the link has been up.
Smooth Round Trip Timer (SRRT)— The number of milliseconds that it takes for an EIGRP packet to be sent to thisneighbor and for the local router to receive an acknowledgment—hence, a round-trip timer. If this number equals 0, apacket has never made a successful round trip.
Retransmission TimeOut (RTO)— The amount of time, in milliseconds, that the EIGRP waits before retransmitting apacket from the retransmission queue to a neighbor.
Queue count (Q)— The number of packets waiting in the queue to be sent out to this neighbor. This value should be 0 or a very low number. A high queue count indicates that data is having trouble getting through.
Sequence Number (Seq-Num)— Sequence number of the last update, query, or reply that was received from this neighbor. If this number equals 0, it indicates that no reliable packets have ever been received from the neighbor, another clear indication of a problem.
show ip eigrp topology Command
The table lists all routes that EIGRP is aware of and shows whether EIGRP is actively processing information on that route. Under most normal conditions, the routes should all be in a passive state and no EIGRP process are running for that route. If the routes are active, this could indicate the dreaded stuck in active, or SIA, state.
RTR1#show ip eigrp topology
IP-EIGRP Topology Table for process 2001
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
r - Reply status
P 172.16.5.0/24, 1 successors, FD is 23394560
via 172.16.1.5 (23394560/281600), Serial0.1
P 172.16.6.0/24, 1 successors, FD is 23394560
via 172.16.1.6 (23394560/281600), Serial0.1
P 172.16.1.0/24, 1 successors, FD is 23368960
via Connected, Serial0.1
P 172.16.2.0/24, 1 successors, FD is 281600
via Connected, Ethernet1
RTR1#
RTR1#show ip eigrp topology 2001 172.16.5.0 255.255.255.0
IP-EIGRP topology entry for 172.16.5.0/24
State is Passive, Query origin flag is 1, 1 Successor(s), FD is 23394560
Routing Descriptor Blocks:
172.16.1.5 (Serial0.1), from 172.16.1.5, Send flag is 0x0
Composite metric is (23394560/281600), Route is Internal
Vector metric:
Minimum bandwidth is 112 Kbit
Total delay is 21000 microseconds
Reliability is 254/255
Load is 1/255
Minimum MTU is 1500
Hop count is 1
RTR1#
The fields to note in this output are as follows:
P— Passive; no EIGRP computation is being performed. This is the ideal state.
A— Active; EIGRP computations are "actively" being performed for this destination. Routes constantly appearing in anactive state indicate a neighbor or query problem. Both are symptoms of the SIA problem.
U— Update; an update packet was sent to this destination.
Q— Query; a query packet was sent to this destination.
R— Reply; a reply packet was sent to this destination.
Route information— IP address of the route or network, its subnet mask, and the successor, or next hop to that network, or the feasible successor.
FD— Feasible distance to the destination network.
show ip protocols Command
This command displays all routing protocols, detailed timer and metric information, as well as routing update information.
RTR1#show ip protocols
Routing Protocol is "eigrp 2001" AS system ID
Outgoing update filter list for all interfaces is
Incoming update filter list for all interfaces is
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 'K' values
EIGRP maximum hopcount 100
EIGRP maximum metric variance 1
Redistributing: eigrp 2001
Automatic network summarization is in effect Auto-summary in effect
Routing for Networks:
172.16.0.0 Networks running EIGRP
Routing Information Sources:
Gateway Distance Last Update
172.16.1.5 90 00:08:48 Routes reported, and administrative
172.16.1.6 90 00:08:52 distance of the route.
Distance: internal 90 external 170 Default admin distance
RTR1#
show ip route Command
This command lists the router's current route or forwarding table. The output lists what routing protocol the route is from—in this case, D for EIGRP internal routes and D EX for routes redistributed into EIGRP. The number behind the route is the administrative distance of the route, followed by the composite metric of the route. The via field explains where the route isfrom, how long ago an update was received, and by what interface it was received.
RTR1#show ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default
U - per-user static route, o - ODR
Gateway of last resort is not set
172.16.0.0/24 is subnetted, 4 subnets
D 172.16.5.0 [90/23394560] via 172.16.1.5, 00:17:51, Serial0.1
D 172.16.6.0 [90/23394560] via 172.16.1.6, 00:29:06, Serial0.1
C 172.16.1.0 is directly connected, Serial0.1
C 172.16.2.0 is directly connected, Ethernet1
RTR1#
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