Yesterday I did a vol3 lab and one of the tasks was to enable EIGRP on a couple
of the switches. I had enabled EIGRP, however I was not getting any routes
installed in the routing table. Look at the output below.

RSRack10SW1#show ip route eigrp
Default gateway is not set
Host Gateway Last Use Total Uses Interface
ICMP redirect cache is empty

This should have rung an alarm bell right here. Default gateway is not set.
When not using ip routing on switches we use ip default-gateway to set a gateway
for management traffic etc. I thought there was an issue with EIGRP so I looked
in the topology table.

RSRack10SW1#show ip eigrp topo
EIGRP-IPv4 Topology Table for AS(10)/ID(150.10.7.7)
Codes: P – Passive, A – Active, U – Update, Q – Query, R – Reply,
r – reply Status, s – sia Status
P 161.10.5.0/24, 1 successors, FD is 2563072
via 161.10.78.8 (2563072/2560512), FastEthernet0/15
P 161.10.10.0/24, 1 successors, FD is 2563072
via 161.10.78.8 (2563072/2560512), FastEthernet0/15
P 161.10.34.0/24, 1 successors, FD is 2563072
via 161.10.78.8 (2563072/2560512), FastEthernet0/15
P 204.12.10.0/24, 1 successors, FD is 2563072
via 161.10.78.8 (2563072/2560512), FastEthernet0/15
P 150.10.9.0/24, 1 successors, FD is 2563072
via 161.10.78.8 (2563072/2560512), FastEthernet0/15
P 150.10.3.0/24, 1 successors, FD is 2563072
via 161.10.78.8 (2563072/2560512), FastEthernet0/15
P 161.10.12.0/24, 1 successors, FD is 2563072
via 161.10.78.8 (2563072/2560512), FastEthernet0/15
P 150.10.6.0/24, 1 successors, FD is 156160
via 161.10.67.6 (156160/128256), FastEthernet0/21
P 161.10.45.0/24, 1 successors, FD is 2563072
via 161.10.78.8 (2563072/2560512), FastEthernet0/15

We have plenty of successors, so there are potential routes in EIGRP.
Remember that a successor in EIGRP is the best path to a prefix.
Now I started thinking about if there was a possibility that I had
these routes installed via another routing protocol but then I
finally realized that I had forgot to turn on ip routing.

RSRack10SW1(config)#ip routing
RSRack10SW1(config)#^Z
RSRack10SW1#

The routes are now getting installed.

RSRack10SW1#show ip route eigrp
51.0.0.0/32 is subnetted, 1 subnets
D EX 51.51.51.51 [170/2563072] via 161.10.78.8, 00:05:01, FastEthernet0/15
54.0.0.0/24 is subnetted, 1 subnets
D 54.10.1.0 [90/2172416] via 161.10.67.6, 00:05:01, FastEthernet0/21
D EX 204.12.10.0/24 [170/2563072] via 161.10.78.8, 00:05:01, FastEthernet0/15
161.10.0.0/16 is variably subnetted, 13 subnets, 3 masks
D EX 161.10.45.0/24
[170/2563072] via 161.10.78.8, 00:05:01, FastEthernet0/15
D EX 161.10.34.0/24
[170/2563072] via 161.10.78.8, 00:05:01, FastEthernet0/15
output edited for brevity

When configuring routing on switches remember that even though we
are allowed to configure the routing protocols, no routes will be
installed if we don’t have ip routing configured.

Don’t forget ip routing on switches
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