Troubleshooting the Cisco 2524 and Cisco 2525

APPEND IX
B
Troubleshooting the Cisco 2524
and Cisco 2525 Routers
This appendix describes how to troubleshoot the Cisco 2524 and Cisco 2525 routers by
referring to the LEDs on the rear panel of the chassis (see Figure 1-2 and Figure 1-3) and
on the network processor modules (see Figure 1-4 through Figure 1-9).
The LEDs indicate the current operating condition of your router. You can observe the
LEDs, note any fault condition that the router is encountering, and then contact your system
administrator or a customer service representative, if necessary. Table B-1 describes the
LEDs on the router chassis and WAN modules.
Table B-1
LEDs
Chassis/Module
LED
State
Description
Router chassis
Power
On steadily
Power is being supplied to the router.
Off
Power is not reaching the router. Verify that the power
supply is plugged into the wall receptacle, and that the
cable from the power supply to the router is
connected.
Flickering
The Ethernet/Token Ring LAN connection is
transmitting and receiving data normally.
Off
The Ethernet/Token Ring LAN connection is not
transmitting or receiving data. Check the
Ethernet/Token Ring cable connection.
Activity
(Ethernet/
Token Ring1)
Troubleshooting the Cisco 2524 and Cisco 2525 Routers B-1
Chassis/Module
LED
State
Description
Router chassis
Ethernet link
(Cisco 2524)2
On
The router senses the Ethernet 10BaseT link integrity
signal, indicating normal operation.
Off
The router is not sensing the Ethernet 10BaseT link
integrity signal. Check the Ethernet 10BaseT cable
connection.
On
The router has been successfully inserted into the
Token Ring, indicating normal operation.
Off
The router has not been successfully inserted into the
Token Ring. Check the Token Ring cable connection.
RX
On
Data is being received at the DTE interface.
TX
On
Data is transmitting from the DTE interface.
CD (Carrier)
On
The DSU/CSU in the module is communicating with
another DSU/CSU.
Loopback
On
The DSU/CSU is in loopback mode.
Alarm
On
An alarm condition is present.
Activity (serial
activity)
Flickering
The serial WAN connection is transmitting and
receiving data normally.
Off
The serial WAN connection is not transmitting or
receiving data. Check the serial cable connection.
Flickering
The ISDN BRI WAN connection is transmitting and
receiving data normally.
Off
The ISDN BRI WAN connection is not transmitting or
receiving data. Check the BRI cable connection.
ACT (ISDN
BRI activity)
Flickering
The ISDN BRI (with integrated NT1) WAN
connection is transmitting and receiving data
normally.
NT1
On
The router detects the ISDN link integrity signal at the
U interface3 and the internal S/T interface4, indicating
that an ISDN connection has been established.
In-ring
(Cisco 2525)
2-wire switched 56-kbps,
4-wire 56/64-kbps, and
factional T1/T1 WAN
DSU/CSU modules
Serial module
ISDN BRI module
ISDN BRI with integrated
NT1 module
Activity (ISDN
BRI activity)
B-2 Cisco 2524 and Cisco 2525 Router User Guide
Running Diagnostic Tests
Chassis/Module
LED
ISDN BRI with integrated
NT1 module
State
Description
Blinking
once per
second
The ISDN connection at the U interface is up, and the
internal S/T interface is coming up. If this state
persists, the ISDN port is either not configured or it is
configured incorrectly.
Blinking
eight times
per second
The ISDN connection at the U interface is coming up.
Off
The router is not detecting the ISDN link integrity
signal. An ISDN connection has not been established.
Check the BRI cable connection.
1. The Token Ring activity LED is labelled ACT.
2. The Ethernet link LED is for the Ethernet 10BaseT port only; it does not work with the Ethernet AUI port.
3. The U interface is from the wall jack (telco interface) to the NT1 device.
4. The S/T interface is from the ISDN port on the module to the microprocessor.
Running Diagnostic Tests
If you have the fractional T1/T1 module, you can use external test equipment with the
monitor jack labeled OUT to monitor signals coming into the RJ-48C port, without
interrupting normal data transmission. You can use the monitor jack labeled IN to inject
data, which would interrupt normal data transmission.
Getting Help
For information on technical support, onsite service, and exchange and repair services,
refer to the Cisco Information Packet publication that shipped with your router.
Troubleshooting the Cisco 2524 and Cisco 2525 Routers B-3
Getting Help
B-4 Cisco 2524 and Cisco 2525 Router User Guide