Table Of Contents
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:
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.) 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
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.
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
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 UseRouter# ping atm interface atm 0 8 35 seg-loopbackType 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-loopbackType 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 InterfacesRouter# show interface atm 0ATM0 is up, line protocol is upHardware is PQUICC_SAR (with Alcatel ADSL Module)Internet address is 188.8.131.52/8MTU 1500 bytes, sub MTU 1500, BW 640 Kbit, DLY 80 usec,reliability 40/255, txload 1/255, rxload 1/255Encapsulation ATM, loopback not setKeepalive not supportedEncapsulation(s):AAL5, PVC mode10 maximum active VCs, 1 current VCCsVC idle disconnect time:300 secondsLast input 01:16:31, output 01:16:31, output hang neverLast clearing of "show interface" counters neverInput queue:0/75/0 (size/max/drops); Total output drops:0Queueing strategy:Per VC Queueing5 minute input rate 0 bits/sec, 0 packets/sec5 minute output rate 0 bits/sec, 0 packets/sec512 packets input, 59780 bytes, 0 no bufferReceived 0 broadcasts, 0 runts, 0 giants, 0 throttles0 input errors, 1024 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort426 packets output, 46282 bytes, 0 underruns0 output errors, 0 collisions, 2 interface resets0 output buffer failures, 0 output buffers swapped outRouter# show interface fastethernet 0Ethernet0 is up, line protocol is upHardware is PQUICC Ethernet, address is 0000.Oc13.a4db(bia0010.9181.1281)Internet address is 184.108.40.206/24MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec,reliability 255/255., txload 1/255, rxload 1/255Encapsulation ARPA, loopback not setKeepalive set (10 sec)Router# show interface dialer 1Dialer 1 is up, line protocol is upHardware is Dialer interfaceInternet address is 220.127.116.11/24MTU 1500 bytes, BW 100000 Kbit, DLY 100000 usec, reliability255/255. txload 1/255, rxload 1/255Encapsulation PPP, loopback not setKeepalive set (10 sec)DTR is pulsed for 5 seconds on resetLCP Closed
Table 14-1 describes possible command output for the show interface command.
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 InterfaceRouter# show atm interface atm 0Interface ATM0:AAL enabled: AAL5 , Maximum VCs:11, Current VCCs:0Maximum Transmit Channels:0Max. Datagram Size:1528PLIM Type:INVALID - 640Kbps, Framing is INVALID,DS3 lbo:short, TX clocking:LINE0 input, 0 output, 0 IN fast, 0 OUT fastAvail bw = 640Config. is ACTIVE
Table 14-2 describes some of the fields shown in the command output.
debug atm Commands
Use the debug commands to troubleshoot configuration problems that you might be having on your network. The debug commands provide extensive, informative displays to help you interpret any possible problems.
Guidelines for Using Debug Commands
Read the following guidelines before using debug commands to ensure appropriate results.
•All debug commands are entered in privileged EXEC mode.
•To view debugging messages on a console, enter the logging console debugging command.
•Most debug commands take no arguments.
•To disable debugging, enter the undebug all command.
•To use debug commands during a Telnet session on your router, enter the terminal monitor command.
Caution Debugging is assigned a high priority in your router CPU process, and it can render your router unusable. For this reason, use debug commands only to troubleshoot specific problems. The best time to use debug commands is during periods of low network traffic so that other activity on the network is not adversely affected.
debug atm errors Command
Use the debug atm errors command to display ATM errors. The no form of this command disables debugging output. Example 14-4 shows a sample output.
Example 14-4 Viewing ATM ErrorsRouter# debug atm errorsATM errors debugging is onRouter#01:32:02:ATM(ATM0.2):VC(3) Bad SAP received 450001:32:04:ATM(ATM0.2):VC(3) Bad SAP received 450001:32:06:ATM(ATM0.2):VC(3) Bad SAP received 450001:32:08:ATM(ATM0.2):VC(3) Bad SAP received 450001:32:10:ATM(ATM0.2):VC(3) Bad SAP received 4500
debug atm events Command
Use the debug atm events command to display events that occur on the ATM interface processor and to diagnose problems in an ATM network. This command provides an overall picture of the stability of the network. The no form of this command disables debugging output.
If the interface is successfully communicating with the Digital Subscriber Line Access Multiplexer (DSLAM) at the telephone company, the modem state is 0x10. If the interface is not communicating with the DSLAM, the modem state is 0x8. Example 14-5 shows an ADSL line that is up and training successfully. Example 14-6 shows an ADSL line that is not communicating correctly. Note that the modem state does not transition to 0x10.
Example 14-5 Viewing ATM Interface Processor Events—SuccessRouter# debug atm eventsRouter#00:02:57: DSL: Send ADSL_OPEN command.00:02:57: DSL: Using subfunction 0xA00:02:57: DSL: Using subfunction 0xA00:02:57: DSL: Sent command 0x500:02:57: DSL: Received response: 0x2600:02:57: DSL: Unexpected response 0x2600:02:57: DSL: Send ADSL_OPEN command.00:02:57: DSL: Using subfunction 0xA00:02:57: DSL: Using subfunction 0xA00:02:57: DSL: Sent command 0x500:03:00: DSL: 1: Modem state = 0x800:03:02: DSL: 2: Modem state = 0x1000:03:05: DSL: 3: Modem state = 0x1000:03:07: DSL: 4: Modem state = 0x1000:03:09: DSL: Received response: 0x2400:03:09: DSL: Showtime!00:03:09: DSL: Sent command 0x1100:03:09: DSL: Received response: 0x6100:03:09: DSL: Read firmware revision 0x1A0400:03:09: DSL: Sent command 0x3100:03:09: DSL: Received response: 0x1200:03:09: DSL: operation mode 0x000100:03:09: DSL: SM: [DMTDSL_DO_OPEN -> DMTDSL_SHOWTIME]
Example 14-6 Viewing ATM Interface Processor Events—FailureRouter# debug atm eventsRouter#00:02:57: DSL: Send ADSL_OPEN command.00:02:57: DSL: Using subfunction 0xA00:02:57: DSL: Using subfunction 0xA00:02:57: DSL: Sent command 0x500:02:57: DSL: Received response: 0x2600:02:57: DSL: Unexpected response 0x2600:02:57: DSL: Send ADSL_OPEN command.00:02:57: DSL: Using subfunction 0xA00:02:57: DSL: Using subfunction 0xA00:02:57: DSL: Sent command 0x500:03:00: DSL: 1: Modem state = 0x800:03:00: DSL: 1: Modem state = 0x800:03:00: DSL: 1: Modem state = 0x800:03:00: DSL: 1: Modem state = 0x800:03:00: DSL: 1: Modem state = 0x800:03:00: DSL: 1: Modem state = 0x8
debug atm packet Command
Use the debug atm packet command to display all process-level ATM packets for both outbound and inbound packets. The output reports information online when a packet is received or a transmission is attempted. The no form of this command disables debugging output.
Caution Because the debug atm packet command generates a significant amount of output for every packet processed, use it only when network traffic is low, so that other system activities are not adversely affected.
The command syntax is:
debug atm packet [interface atm number [vcd vcd-number][vc vpi/vci number]]
no debug atm packet [interface atm number [vcd vcd-number][vc vpi/vci number]]
where the keywords are defined as follows:
interface atm number (Optional) ATM interface or subinterface number.
vcd vcd-number (Optional) Number of the virtual circuit designator (VCD).
vc vpi/vci number VPI/VCI value of the ATM PVC.
Example 14-7 shows sample output for the debug atm packet command.
Example 14-7 Viewing ATM Packet ProcessingRouter# debug atm packetRouter#01:23:48:ATM0(O):VCD:0x1 VPI:0x1 VCI:0x64 DM:0x0 SAP:AAAA CTL:03 OUI:000000 TYPE:0800 Length:0x7001:23:48:4500 0064 0008 0000 FF01 9F80 0E00 0010 0E00 0001 0800 A103 0AF3 17F7 000001:23:48:0000 004C BA10 ABCD ABCD ABCD ABCD ABCD ABCD ABCD ABCD ABCD ABCD ABCD ABCD01:23:48:ABCD ABCD ABCD ABCD ABCD ABCD ABCD ABCD ABCD ABCD ABCD ABCD ABCD ABCD ABCD01:23:48:ABCD ABCD ABCD ABCD ABCD01:23:48:01:23:48:ATM0(I):VCD:0x1 VPI:0x1 VCI:0x64 Type:0x0 SAP:AAAA CTL:03 OUI:000000 TYPE:0800 Length:0x7001:23:48:4500 0064 0008 0000 FE01 A080 0E00 0001 0E00 0010 0000 A903 0AF3 17F7 000001:23:48:0000 004C BA10 ABCD ABCD ABCD ABCD ABCD ABCD ABCD ABCD ABCD ABCD ABCD ABCD01:23:48:ABCD ABCD ABCD ABCD ABCD ABCD ABCD ABCD ABCD ABCD ABCD ABCD ABCD ABCD ABCD01:23:48:ABCD ABCD ABCD ABCD ABCD01:23:48:
Table 14-3 describes some of the fields shown in the debug atm packet command output.
Software Upgrade Methods
Several methods are available for upgrading software on the Cisco 850 and Cisco 870 series access routers, including:
•Copy the new software image to flash memory over the LAN or WAN while the existing Cisco IOS software image is operating.
•Copy the new software image to flash memory over the LAN while the boot image (ROM monitor) is operating.
•Copy the new software image over the console port while in ROM monitor mode.
•From ROM monitor mode, boot the router from a software image that is loaded on a TFTP server. To use this method, the TFTP server must be on the same LAN as the router.
Recovering a Lost Password
To recover a lost enable or lost enable-secret password:
3. Reset the Password and Save Your Changes (for lost enable secret passwords only)
Note Recovering a lost password is only possible when you are connected to the router through the console port. These procedures cannot be performed through a Telnet session.
Tip See the "Hot Tips" section on Cisco.com for additional information on replacing enable secret passwords.
Change the Configuration Register
To change a configuration register, follow these steps:
Step 1 Connect an ASCII terminal or a PC running a terminal emulation program to the CONSOLE port on the rear panel of the router.
Step 2 Configure the terminal to operate at 9600 baud, 8 data bits, no parity, and 1 stop bit.
Step 3 If you still have access to the router, enter the show version command at the privilege EXEC prompt to display the existing configuration register value (shown in bold at the bottom of this output example). Record the setting of the configuration register.Router# show versionCisco IOS Software, C870 Software (C870-ADVENTERPRISEK9-M), Version 12.3(nightly.PCBU_WIRELESS041110) NIGHTLY BUILD, synced to haw_t_pi1_pcbu HAW_T_PI1_PCBU_20040924Copyright (c) 1986-2004 by Cisco Systems, Inc.Compiled Thu 11-Nov-04 03:37 by jsomebodyROM: System Bootstrap, Version 18.104.22.168(20030916:100755) [jsomebody],DEVELOPMENT SOFTWARERouter uptime is 2467 minutesSystem returned to ROM by power-onSystem image file is "flash:c870-adventerprisek9-mz.pcbu_wireless.041110"This product contains cryptographic features and is subject to UnitedStates and local country laws governing import, export, transfer anduse. Delivery of Cisco cryptographic products does not implyuse. Delivery of Cisco cryptographic products does not implyImporters, exporters, distributors and users are responsible forcompliance with U.S. and local country laws. By using this product youagree to comply with applicable laws and regulations. If you are unableto comply with U.S. and local laws, return this product immediately.A summary of U.S. laws governing Cisco cryptographic products may be found at:http://www.cisco.com/wwl/export/crypto/tool/stqrg.htmlIf you require further assistance please contact us by sending email email@example.com.Cisco 877 (MPC8272) processor (revision 0x00) with 59392K/6144K bytes of memory.Processor board IDMPC8272 CPU Rev: Part Number 0xC, Mask Number 0x104 FastEthernet interfaces1 ATM interface1 802.11 Radio128K bytes of non-volatile configuration memory.20480K bytes of processor board System flash (Intel Strataflash)Configuration register is 0x2102
Step 4 If you do not have access to the router (because of a lost login or tacacs password), you can safely consider that your configuration register is set to 0x2102.
Step 5 Using the power switch, turn off the router and then turn it back on.
Step 6 Enter the config-register 0x01 command from privileged EXEC mode To enable the break setting (indicated by the value of bit 8 in the configuration register).
•Break enabled—Bit 8 is set to 0.
•Break disabled (default setting)—Bit 8 is set to 1.
Reset the Router
Note Disable the 'no service password recovery' setting in the router configuration or the Break key will be ignored when attempting to get into rommon.
To reset the router, follow these steps:
Step 1 If break is enabled, go to Step 2. If break is disabled, turn the router off (O), wait 5 seconds, and turn it on (|) again. Within 60 seconds, press the Break key. The terminal displays the ROM monitor prompt. Go to Step 3.
Note Some terminal keyboards have a key labeled Break. If your keyboard does not have a Break key, see the documentation that came with the terminal for instructions on how to send a break.
Step 2 Press break. The terminal displays the following prompt:rommon 2>
Step 3 Enter confreg 0x2142 to reset the configuration register:rommon 2> confreg 0x2142
Step 4 Initialize the router by entering the reset command:rommon 2> reset
The router cycles its power, and the configuration register is set to 0x2142. The router uses the boot ROM system image, indicated by the system configuration dialog:--- System Configuration Dialog ---
Step 5 Enter no in response to the prompts until the following message is displayed:Press RETURN to get started!
Step 6 Press Return. The following prompt appears:Router>
Step 7 Enter the enable command to enter enable mode. Configuration changes can be made only in enable mode:Router> enable
The prompt changes to the privileged EXEC prompt:Router#
Step 8 Enter the show startup-config command to display an enable password in the configuration file:Router# show startup-config
If you are recovering an enable password, do not perform the steps in the following "Reset the Password and Save Your Changes" section. Instead, complete the password recovery process by performing the steps in the "Reset the Configuration Register Value" section.
If you are recovering an enable secret password, it is not displayed in the show startup-config command output. Complete the password recovery process by performing the steps in the following "Reset the Password and Save Your Changes" section.
Reset the Password and Save Your Changes
To reset your password and save the changes, follow these steps:
Step 1 Enter the configure terminal command to enter global configuration mode:Router# configure terminal
Step 2 Enter the enable secret command to reset the enable secret password in the router:Router(config)# enable secret password
Step 3 Enter exit to exit global configuration mode:Router(config)# exit
Step 4 Save your configuration changes:Router# copy running-config startup-config
Reset the Configuration Register Value
To reset the configuration register value after you have recovered or reconfigured a password, follow these steps:
Step 1 Enter the configure terminal command to enter global configuration mode:Router# configure terminal
Step 2 Enter the configure register command and the original configuration register value that you recorded.Router(config)# config-reg value
Step 3 Enter exit to exit configuration mode:Router(config)# exit
Note To return to the configuration being used before you recovered the lost enable password, do not save the configuration changes before rebooting the router.
Step 4 Reboot the router, and enter the recovered password.
Managing Your Router with SDM
The Cisco SDM tool is a free software configuration utility, supporting the Cisco 850 and Cisco 870 series access routers. It includes a web-based GUI that offers the following features: