Troubleshooting guide

11-27
ATM and Layer 3 Switch Router Troubleshooting Guide
OL-1969-01
Chapter 11 Troubleshooting Layer 3 Network Connections
Troubleshooting IP Layer 3 Connections
Checking the IP Routing Table
Follow these steps to verify the IP routing tables in the IP Layer 3 connection shown in Figure 11-15.
Figure 11-15 Displaying Router Table Information
Step 1 From the Catalyst 8540-1, use the show ip route command to verify the status of the IP routing table
for the example network shown in Figure 11-15.
C8540CSR-1# 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, ia - IS-IS inter area
* - candidate default, U - per-user static route, o - ODR
P - periodic downloaded static route
Gateway of last resort is not set
C 10.85.40.0/24 is directly connected, Fast Ethernet 1/0/15
D 10.85.45.0/24 [90/30720] via 10.85.66.0, 01:22:23, Gigabit Ethernet 0/0/0
C 10.85.66.0/24 is directly connected, Gigabit Ethernet 0/0/0
8540CSR-1#
Note All the networks are directly connected except for 10.85.45.0, which was learned through EIGRP, via
interface Gigabit Ethernet 0/0/0.
Step 2 From the Catalyst 8540-1, use the show ip route command to display the network connecting Host B to
Catalyst 8540-2 with IP address 10.85.45.0.
C8540CSR-1# show ip route 10.85.40.0
Last update from 10.85.66.5 on GigabitEthernet 0/0/0, 1d16h ago
Routing Descriptor Blocks:
* 10.85.66.5, from 10.85.45.9, 1d16h ago, via GigabitEthernet 0/0/0
C8540CSR-1#
The display confirms the route to network 10.85.45.0, which exists in the routing table and was learned
via IP address 10.85.66.5 through Gigabit Ethernet interface 0/0/0.
Host A Catalyst 8540-2Catalyst 8540-1 Host B
10.85.40.0/24 10.85.66.0/24 10.85.45.0/24
.5 .254 .10 .5 .254 .5
MAC:
00:10.e3:aa...
Fast Ethernet connection (fast 1/0/15 on C8540-1)
Gigabit Ethernet connection (giga 0/0/0 on C8540-1)
MAC:
00:90.21:bb...
MAC:
00:90.21:dd...
MAC:
00:90.21:ff...
MAC:
00:90.21:cc...
MAC:
00:90.21:ee...
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