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C H A P T E R
14-1
Cisco 850 Series and Cisco 870 Series Access Routers Software Configuration Guide
OL-5332-01
14
Troubleshooting
Use the information in this chapter to help isolate problems you might encounter or to rule out the router
as the source of a problem. This chapter contains the following sections:
•
Getting Started
•
Before Contacting Cisco or Your Reseller
•
ADSL Troubleshooting
•
SHDSL Troubleshooting
•
ATM Troubleshooting Commands
•
Software Upgrade Methods
•
Recovering a Lost Password
•
Managing Your Router with SDM
Getting Started
Before troubleshooting a software problem, you must connect a terminal or PC to the router using the
light-blue console port. (For information on making this connection, see the documentation listed in the
“Related Documents” section on page 14
.) With a connected terminal or PC, you can view status
messages from the router and enter commands to troubleshoot a problem.
You can also remotely access the interface (Ethernet, ADSL, or telephone) by using Telnet. The Telnet
option assumes that the interface is up and running.
Before Contacting Cisco or Your Reseller
If you cannot locate the source of a problem, contact your local reseller for advice. Before you call, you
should have the following information ready:
•
Chassis type and serial number
•
Maintenance agreement or warranty information
•
Type of software and version number
•
Date you received the hardware
•
Brief description of the problem
•
Brief description of the steps you have taken to isolate the problem
Page 142 / 196
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Cisco 850 Series and Cisco 870 Series Access Routers Software Configuration Guide
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Chapter 14
Troubleshooting
ADSL Troubleshooting
ADSL Troubleshooting
If you experience trouble with the ADSL connection, verify the following:
•
The ADSL line is connected and is using pins 3 and 4. For more information on the ADSL
connection, see the hardware guide for your router.
•
The ADSL CD LED is on. If it is not on, the router may not be connected to the DSL access
multiplexer (DSLAM). For more information on the ADSL LEDs, see the hardware installation
guide specific for your router
.
•
The correct Asynchronous Transfer Mode (ATM) virtual path identifier/virtual circuit identifier
(VPI/VCI) is being used.
•
The DSLAM supports discrete multi-tone (DMT) Issue 2.
•
The ADSL cable that you connect to the Cisco router must be 10BASE-T Category 5, unshielded
twisted-pair (UTP) cable. Using regular telephone cable can introduce line errors.
SHDSL Troubleshooting
Symmetrical high-data-rate digital subscriber line (SHDSL) is available on Cisco 878 and Cisco 1803
router models. If you experience trouble with the SHDSL connection, verify the following:
•
The SHDSL line is connected and using pins 3 and 4. For more information on the G.SHDSL
connection, see the hardware guide for your router.
•
The G.SHDSL LED is on. If it is not on, the router may not be connected to the DSL access
multiplexer (DSLAM). For more information on the G.SHDSL LED, see the hardware installation
guide specific for your router
.
•
The correct asynchronous transfer mode (ATM) virtual path identifier/virtual circuit identifier
(VPI/VCI) is being used.
•
The DSLAM supports the G.SHDSL signaling protocol.
Use the
show controllers dsl 0
command in EXEC mode to view an SHDSL configuration.
ATM Troubleshooting Commands
Use the following commands to troubleshoot your ATM interface.
•
ping atm interface Command
•
show interface Command
•
show atm interface Command
•
debug atm Commands
Page 143 / 196
14-3
Cisco 850 Series and Cisco 870 Series Access Routers Software Configuration Guide
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Chapter 14
Troubleshooting
ATM Troubleshooting Commands
ping atm interface Command
Use the
ping atm interface
command to determine whether a particular PVC is in use. The PVC does
not need to be configured on the router to use this command.
Example 14-1
shows the use of this
command to determine whether PVC 8/35 is in use.
Example 14-1
Determining If a PVC Is in Use
Router#
ping atm interface atm 0 8 35 seg-loopback
Type escape sequence to abort.
Sending 5, 53-byte segment OAM echoes, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 148/148/148 ms
This command sends five OAM F5 loopback packets to the DSLAM (segment OAM packets). If the
PVC is configured at the DSLAM, the ping is successful.
To test whether the PVC is being used at the aggregator, enter the following command:
Router#
ping atm interface atm 0 8 35 end-loopback
Type escape sequence to abort.
Sending 5, 53-byte end-to-end OAM echoes, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 400/401/404 ms
This command sends end-to-end OAM F5 packets, which are echoed back by the aggregator.
show interface Command
Use the
show interface
command to display the status of all physical ports (Ethernet and ATM) and
logical interfaces on the router.
Table 14-1
describes messages in the command output.
Example 14-2
Viewing Status of Selected Interfaces
Router#
show interface atm 0
ATM0 is up, line protocol is up
Hardware is PQUICC_SAR (with Alcatel ADSL Module)
Internet address is 14.0.0.16/8
MTU 1500 bytes, sub MTU 1500, BW 640 Kbit, DLY 80 usec,
reliability 40/255, txload 1/255, rxload 1/255
Encapsulation ATM, loopback not set
Keepalive not supported
Encapsulation(s):AAL5, PVC mode
10 maximum active VCs, 1 current VCCs
VC idle disconnect time:300 seconds
Last input 01:16:31, output 01:16:31, output hang never
Last clearing of "show interface" counters never
Input queue:0/75/0 (size/max/drops); Total output drops:0
Queueing strategy:Per VC Queueing
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
512 packets input, 59780 bytes, 0 no buffer
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 1024 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
Page 144 / 196
14-4
Cisco 850 Series and Cisco 870 Series Access Routers Software Configuration Guide
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Chapter 14
Troubleshooting
ATM Troubleshooting Commands
426 packets output, 46282 bytes, 0 underruns
0 output errors, 0 collisions, 2 interface resets
0 output buffer failures, 0 output buffers swapped out
Router#
show interface fastethernet 0
Ethernet0 is up, line protocol is up
Hardware is PQUICC Ethernet, address is 0000.Oc13.a4db
(bia0010.9181.1281)
Internet address is 170.1.4.101/24
MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec,
reliability 255/255., txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Router#
show interface dialer 1
Dialer 1 is up, line protocol is up
Hardware is Dialer interface
Internet address is 1.1.1.1/24
MTU 1500 bytes, BW 100000 Kbit, DLY 100000 usec, reliability
255/255. txload 1/255, rxload 1/255
Encapsulation PPP, loopback not set
Keepalive set (10 sec)
DTR is pulsed for 5 seconds on reset
LCP Closed
Table 14-1
describes possible command output for the
show interface
command.
Table 14-1
show interface Command Output Description
Output
Cause
For ATM Interfaces
ATM 0 is up, line protocol is up
The ATM line is up and operating correctly.
ATM 0 is down, line protocol is down
•
The ATM interface has been disabled with the
shutdown
command.
or
•
The ATM line is down, possibly because the
ADSL cable is disconnected or because the
wrong type of cable is connected to the ATM
port.
ATM 0.
n
is up, line protocol is up
The specified ATM subinterface is up and operating
correctly.
ATM 0.
n
is administratively down, line protocol
is down
The specified ATM subinterface has been disabled
with the
shutdown
command.
ATM 0.
n
is down, line protocol is down
The specified ATM subinterface is down, possibly
because the ATM line has been disconnected (by the
service provider).
For Fast Ethernet Interfaces
Fast Ethernet
n
is up, line protocol is up
The specified Fast Ethernet interface is connected to
the network and operating correctly.
Fast Ethernet
n
is up, line protocol is down
The specified Fast Ethernet interface has been
correctly configured and enabled, but the Ethernet
cable might be disconnected from the LAN.
Page 145 / 196
14-5
Cisco 850 Series and Cisco 870 Series Access Routers Software Configuration Guide
OL-5332-01
Chapter 14
Troubleshooting
ATM Troubleshooting Commands
show atm interface Command
To display ATM-specific information about an ATM interface, use the
show atm interface atm 0
command from privileged EXEC mode, as shown in
Example 14-3
.
Example 14-3
Viewing Information About an ATM Interface
Router#
show atm interface atm 0
Interface ATM0:
AAL enabled: AAL5 , Maximum VCs:11, Current VCCs:0
Maximum Transmit Channels:0
Max. Datagram Size:1528
PLIM Type:INVALID - 640Kbps, Framing is INVALID,
DS3 lbo:short, TX clocking:LINE
0 input, 0 output, 0 IN fast, 0 OUT fast
Avail bw = 640
Config. is ACTIVE
Table 14-2
describes some of the fields shown in the command output.
Fast Ethernet
n
is administratively down, line
protocol is down
The specified Fast Ethernet interface has been
disabled with the
shutdown
command, and the
interface is disconnected.
For Dialer Interfaces
Dialer
n
is up, line protocol is up
The specified dialer interface is up and operating
correctly.
Dialer
n
is down, line protocol is down
•
This is a standard message and may not indicate
anything is actually wrong with the
configuration.
or
•
If you are having problems with the specified
dialer interface, this can mean it is not
operating, possibly because the interface has
been brought down with the
shutdown
command, or the ADSL cable is disconnected.
Table 14-1
show interface Command Output Description (continued)
Output
Cause
Table 14-2
show atm interface Command Output Description
Field
Description
ATM interface
Interface number. Always 0 for the Cisco 850 and Cisco 870 series access routers.
AAL enabled
Type of AAL enabled. The Cisco 850 and Cisco 870 series access routers support
AAL5.
Maximum VCs
Maximum number of virtual connections this interface supports.
Current VCCs
Number of active virtual channel connections (VCCs).

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