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Cisco Intrusion Prevention System Sensor CLI Configuration Guide for IPS 7.2
OL-29168-01
Appendix C Troubleshooting
Troubleshooting the Appliance
Duplicate IP Address Shuts Interface Down

If you have two newly imaged sensors with the same IP address that come up on the same network at the

same time, the interface shuts down. Linux prevents the command and control interface from activating

if it detects an address conflict with another host.

To verify that the sensor in question does not have an IP address conflict with another host on the

network, follow these steps:

Step 1
Log in to the CLI.
Step 2

Determine whether the interface is up. If the output says the command and control interface link status

is down, there is a hardware issue or an IP address conflict.

sensor# show interfaces
Interface Statistics
Total Packets Received = 0
Total Bytes Received = 0
Missed Packet Percentage = 0
Current Bypass Mode = Auto_off
MAC statistics from interface GigabitEthernet0/1
Media Type = backplane
Missed Packet Percentage = 0
Inline Mode = Unpaired
Pair Status = N/A
Link Status = Up
Link Speed = Auto_1000
Link Duplex = Auto_Full
Total Packets Received = 0
Total Bytes Received = 0
Total Multicast Packets Received = 0
Total Broadcast Packets Received = 0
Total Jumbo Packets Received = 0
Total Undersize Packets Received = 0
Total Receive Errors = 0
Total Receive FIFO Overruns = 0
Total Packets Transmitted = 0
Total Bytes Transmitted = 0
Total Multicast Packets Transmitted = 0
Total Broadcast Packets Transmitted = 0
Total Jumbo Packets Transmitted = 0
Total Undersize Packets Transmitted = 0
Total Transmit Errors = 0
Total Transmit FIFO Overruns = 0
MAC statistics from interface GigabitEthernet0/0
Media Type = TX
Link Status = Up
Link Speed = Auto_100
Link Duplex = Auto_Full
Total Packets Received = 1822323
Total Bytes Received = 131098876
Total Multicast Packets Received = 20
Total Receive Errors = 0
Total Receive FIFO Overruns = 0
Total Packets Transmitted = 219260
Total Bytes Transmitted = 103668610
Total Transmit Errors = 0
Total Transmit FIFO Overruns = 0
sensor#
Step 3

Make sure the sensor cabling is correct.