Troubleshooting Dialin Connections

Use the following procedure to configure a Cisco router to automatically attempt to discover what kind of modem is connected to the line and then to configure the modem:

Step 1 To discover the type of modem attached to your router, use the modem autoconfigure discovery line configuration command.

Step 2 When the modem is successfully discovered, configure the modem automatically using the modem autoconfigure type modem-name line configuration command.

If you want to display the list of modems for which the router has entries, use the show modemcap modem-name. If you want to change a modem value that was returned from the show modemcap command, use the modemcap edit modem-name attribute value line configuration command.

For complete information on the use of these commands, refer to the Cisco IOS Access Services Configuration Guide and Access Services Command Reference.

Step 2 If the connection is refused, there may already be a user connected to that port. Use the show users exec command to determine whether the line is being used. If desired, the line can be cleared from the console using the clear line privileged exec command. When you are certain the line is not in use, attempt the Telnet connection again.

When connectivity problems occur, important output appears in the Modem state and the Modem hardware state fields.

Modem State	Modem Hardware State	Meaning
Idle	CTS noDSR DTR RTS	These are the proper modem states for connections between an access server or router and a modem (when there is no incoming call). Output of any other kind generally indicates a problem.
Ready	---	If the modem state is Ready instead of Idle, there are three possibilities: Modem control is not configured on the access server or router. Configure the access server or router with the modem inout line configuration command. A session exists on the line. Use the show users exec command and use the clear line privileged exec command to stop the session if desired. DSR is high. There are two possible reasons for this: Cabling problems---If your connector uses DB-25 pin 6 and has no pin 8, you must move the pin from 6 to 8 or get the appropriate connector. Modem configured for DCD always high---The modem should be reconfigured to have DCD high only on CD.1 This is usually done with the &C1 modem command (refer to Figure 16-1), but check your modem documentation for the exact syntax for your modem. If your software does not support modem control, you must configure the access server line to which the modem is connected with the no exec line configuration command. Clear the line with the clear line privileged exec command, initiate a reverse Telnet session with the modem, and reconfigure the modem so that DCD is high only on CD. End the Telnet session by entering disconnect and reconfigure the access server line with the exec line configuration command.
Ready	noCTS noDSR DTR RTS	There are four possibilities for the noCTS string appearing in the Modem hardware state field: The modem is turned off. The modem is not properly connected to the access server. Check the cabling connections from the modem to the access server. Incorrect cabling (either rolled MDCE, or straight MDTE, but without the pins moved). See Table 16-2 for information on the recommended cabling configuration. The modem is not configured for hardware flow control. Disable hardware flow control on the access server with the no flowcontrol hardware line configuration command and then enable hardware flow control on the modem via a reverse Telnet session. (Consult your modem documentation and see the section "Establishing a Reverse Telnet Session to a Modem" earlier in this chapter.) Reenable hardware flow control on the access server with the flowcontrol hardware line configuration command.
Ready	CTS DSR DTR RTS	There are two possibilities for the presence of the DSR string instead of the noDSR string in the Modem hardware state field: Incorrect cabling (either rolled MDCE, or straight MDTE, but without the pins moved). See Table 16-2 for information on the recommended cabling configuration. The modem is configured for DCD always high. Reconfigure the modem so that DCD is only high on CD. This is usually done with the &C1 modem command (see Figure 16-1), but check your modem documentation for the exact syntax for your modem. Configure the access server line to which the modem is connected with the no exec line configuration command. Clear the line with the clear line privileged exec command, initiate a reverse Telnet session with the modem, and reconfigure the modem so that DCD is high only on CD. End the Telnet session by entering disconnect. Reconfigure the access server line with the exec line configuration command.
Ready	CTS* DSR* DTR RTS2	If this string appears in the Modem hardware state field, modem control is probably not enabled on the access server. Use the modem inout line configuration command to enable modem control on the line. See Table 16-2 for more information on configuring modem control on an access server or router line.

1CD = Carrier Detect 2A * next to a signal indicates one of two things: The signal has changed within the past few seconds or the signal is not being used by the modem control method selected.

Possible Causes	Suggested Actions
Modem control is not enabled on the access server or router	Step 1 Use the show line exec command on the access server or router. The output for the auxiliary port should show inout or RIisCD in the Modem column. This indicates that modem control is enabled on the line of the access server or router. For an explanation of show line output, see the "Using debug Commands" section earlier in this chapter. Step 2 Configure the line for modem control using the modem inout line configuration command. Modem control is now enabled on the access server. Example: The following example illustrates how to configure a line for both incoming and outgoing calls: line 5 modem inout
Modem control is not enabled on the access server or router	Note: Be certain to use the modem inout command and not the modem ri-is-cd command while the connectivity of the modem is in question. The latter command allows the line to accept incoming calls only. Outgoing calls will be refused, making it impossible to establish a Telnet session with the modem to configure it. If you want to enable the modem ri-is-cd command, do so only after you are certain the modem is functioning correctly.
Incorrect cabling	Step 1 Check the cabling between the modem and the access server or router. Confirm that the modem is connected to the auxiliary port on the access server or router with a rolled RJ-45 cable and an MMOD DB-25 adapter. This cabling configuration is recommended and supported by Cisco for RJ-45 ports. (These connectors are typically labelled "Modem.") Step 2 Use the show line exec command to verify that the cabling is correct. See the explanation of the show line command output in the section "Using debug Commands" earlier in this chapter.
Hardware problem	Step 1 Verify that you are using the correct cabling and that all connections are good. Step 2 Check all hardware for damage, including cabling (broken wires), adapters (loose pins), access server ports, and modem. Step 3 See "Troubleshooting Hardware and Booting Problems," for more information on hardware troubleshooting.

Possible Causes	Suggested Actions
Incorrect cabling	Step 1 Check the cabling between the modem and the access server or router. Confirm that the modem is connected to the auxiliary port on the access server or router with a rolled RJ-45 cable and an MMOD DB-25 adapter. This cabling configuration is recommended and supported by Cisco for RJ-45 ports. (These connectors are typically labelled "Modem.") Types of RJ-45 Cabling: There are two types of RJ-45 cabling: straight and rolled. If you hold the two ends of an RJ-45 cable side-by-side, you'll see eight colored strips, or pins, at each end. If the order of the colored pins is the same at each end, then the cable is straight. If the order of the colors is reversed at each end, then the cable is rolled. The rolled cable (CAB-500RJ) is standard with Cisco's 2500/CS500. Note: CAB-OCTAL-ASYNC, the eight-port RJ-45 adapter that is used with the Cisco 2509, 2510, 2511, and 2512, is the same as a rolled cable. RJ-45 Port Pinouts: This chart shows the pinouts for RJ-45 console and AUX ports. The console port does not use RTS/CTS: Console/Auxiliary Port (DTE1) Pin Signal Input/Output 1 RTS Output 2 DTR Output 3 TXD Output 4 GND --- 5 GND --- 6 RXD Input 7 DSR Input 8 CTS Input Step 2 Use the show line exec command to verify that the cabling is correct. See the explanation of the show line command output in the section "Using debug Commands" earlier in this chapter.
Modem hardware problem	Check the modem's physical connection. Make sure the modem is on and is connected securely to the correct port. Make sure the transmit and receive indicator lights flash when the chat script is running.
No interesting packets defined	Step 1 Use the show running-config privileged exec command to view the router configuration. Check the dialer-list interface configuration command entries to see which access lists, if any, are being used to define interesting traffic. Step 2 Make sure the access lists referenced by the dialer-list commands specify all traffic that should bring up the link (interesting traffic). Step 3 If necessary, modify the access list commands so that they define the proper traffic as interesting.
Missing chat script	Step 1 Use the debug chat privileged exec command to check whether there is a chat script running. Step 2 If there is no chat script running, use the start-chat privileged exec command or another appropriate command to start the chat script on the line. For detailed information about creating and configuring chat scripts, refer to the Cisco IOS Access Services Configuration Guide and Access Services Command Reference.
Bad chat script	Step 1 Establish a reverse Telnet session to the modem and step through each step of the chat script. Step 2 Verify that the command response to each chat script step is correct. Step 3 Fix any inconsistencies you find in the chat script. For detailed information about creating and configuring chat scripts, refer to the Cisco IOS Access Services Configuration Guide and Access Services Command Reference.

1DTE = data terminal equipment

Possible Causes	Suggested Actions
Incorrect cabling	Step 1 Check the cabling between the modem and the access server or router. Confirm that the modem is connected to the auxiliary port on the access server or router with a rolled RJ-45 cable and an MMOD DB-25 adapter. This cabling configuration is recommended and supported by Cisco for RJ-45 ports. (These connectors are typically labeled "Modem.") There are two types of RJ-45 cabling: straight and rolled. If you hold the two ends of an RJ-45 cable side-by-side, you'll see eight colored strips, or pins, at each end. If the order of the colored pins is the same at each end, then the cable is straight. If the order of the colors is reversed at each end, then the cable is rolled. The rolled cable (CAB-500RJ) is standard with Cisco's 2500/CS500. Step 2 Use the show line exec command to verify that the cabling is correct. See the explanation of the show line command output in the section "Using debug Commands" earlier in this chapter.
Modem control not enabled on access server or router	Step 1 Observe the remote modem to see whether it is receiving a DTR signal from the router. Most modems have a DTR indicator light. Check the modem documentation to interpret the indicator lights. Step 2 If the DTR indicator light is on, the modem is seeing a DTR signal from the router. You can also enter the show line exec command to check for DTR. If the modem hardware state shows the string noDTR, then the router is configured to hold DTR low and the modem is not seeing a DTR signal. Step 3 Configure modem control using either the modem inout or the modem ri-is-cd line configuration command.
Misconfigured dialer map commands	Step 1 Use the show running-config privileged exec command to view the router configuration. Check all dialer map statements to make sure they are configured correctly. Step 2 Correct dialer map statements as necessary, making certain that all options are specified properly. For detailed information on configuring dialer maps, refer to the Cisco IOS Wide-Area Networking Configuration Guide and Wide-Area Networking Command Reference.
Remote modem not set to auto-answer	Step 1 Check the remote modem to see whether it is set to auto-answer. Usually, an AA indicator light is on when auto-answer is set. Step 2 Set the remote modem to auto-answer if it is not already set. To find out how to verify and change the modem's settings, refer to your modem documentation.
Wrong telephone line attached to remote modem	Step 1 Make sure you are using the correct telephone line. Replace the remote modem with a telephone and call again. If the phone rings, you are using the correct telephone line. Step 2 Contact the telephone company to make sure that the line is good.
Remote modem not attached to a router	Step 1 Make sure the remote modem is attached to a router or other device that is asserting DTR. Step 2 Most modems have an LED indicator for DTR. Check to make sure this indicator comes on.

Possible Causes	Suggested Actions
Modem speed setting is not locked	Step 1 Use the show line exec command on the access server or router. The output for the auxiliary port should indicate the currently configured Tx1 and Rx2 speeds. For an explanation of the output from the show line command, see the section "Using debug Commands" earlier in this chapter. Step 2 If the line is not configured to the correct speed, use the speed line configuration commands to set the line speed on the access server or router line. Set the value to the highest speed in common between the modem and the access server or router port. To set the terminal baud rate, use the speed line configuration command. This command sets both the transmit (to terminal) and receive (from terminal) speeds. Syntax: speed bps Syntax Description: bps---Baud rate in bits per second (bps). The default is 9600 bps. Example: The following example sets lines 1 and 2 on a Cisco 2509 access server to 115200 bps: line 1 2 speed 115200 Note: If for some reason you cannot use flow control, limit the line speed to 9600 bps. Faster speeds are likely to result in lost data. Step 3 Use the show line exec command again and confirm that the line speed is set to the desired value.
Modem speed setting is not locked	Step 4 When you are certain the access server or router line is configured for the desired speed, initiate a reverse Telnet session to the modem on that line. For more information, see the section "Establishing a Reverse Telnet Session to a Modem" earlier in this chapter. Step 5 Use a modem command string that includes the lock DTE speed command for your modem. See your modem documentation for exact configuration command syntax. Note: The lock DTE speed command, which might also be referred to as port rate adjust or buffered mode, is often related to the way the modem handles error correction. This command varies widely from one modem to another. Locking the modem speed ensures that the modem always communicates with the Cisco access server or router at the speed configured on the Cisco auxiliary port. If this command is not used, the modem reverts to the speed of the data link (the telephone line) instead of communicating at the speed configured on the access server.
Modem control is not enabled on the access server or router	Step 1 Use the show line exec command on the access server or router. The output for the auxiliary port should show inout or RIisCD in the Modem column. This indicates that modem control is enabled on the line of the access server or router. For an explanation of the show line output, see the "Using debug Commands" section earlier in this chapter. Step 2 Configure the line for modem control using the modem inout line configuration command. Modem control is now enabled on the access server. Example: The following example illustrates how to configure a line for both incoming and outgoing calls: line 5 modem inout
Modem control is not enabled on the access server or router	Note: Be certain to use the modem inout command instead of the modem ri-is-cd command while the connectivity of the modem is in question. The latter command allows the line to accept incoming calls only. Outgoing calls will be refused, making it impossible to establish a Telnet session with the modem to configure it. If you want to enable the modem ri-is-cd command, do so only after you are certain the modem is functioning correctly.
PPP authentication fails	Step 1 Use the debug ppp chap privileged exec command to see whether PPP authentication was successful. Check the output for the phrase "Passed authentication with remote." If you see this output, authentication was successful. Step 2 If PPP authentication was not successful, verify the username and password configured on the router. The username and password you enter must be identical to those configured on the router. Note: Usernames and passwords are case sensitive.
Local router not waiting long enough to connect	Step 1 Use the show dialer exec command to see the configured dialer timeout. A timeout value shorter than 120 seconds will not be long enough. Step 2 Configure the local router to wait longer for the connection. Use the dialer wait-for-carrier-time seconds command to modify the configuration. Make sure you specify at least a 120-second timeout.
Chat script problem	Step 1 Enter the debug chat privileged exec command. If you see the output "Success" at the end of the chat script, the chat script completed successfully. Step 2 Make the timeout in the chat script longer at the point where it fails. Step 3 If the problem persists, verify that the command response to each chat script step is correct. Open a reverse Telnet session to the modem and step through the chat script. Step 4 Fix any inconsistencies you find in the chat script. For detailed information about creating and configuring chat scripts, refer to the Cisco IOS Access Services Configuration Guide and Access Services Command Reference.

1Tx = transmit 2Rx = receive

Possible Causes	Suggested Actions
Autoselect is enabled on the line	Attempt to access exec mode by issuing a carriage return.
Line is configured with the no exec command	Step 1 Use the show line exec command to view the status of the appropriate line. Check the Capabilities field to see whether it says "exec suppressed." If this is the case, the no exec line configuration command is enabled. Step 2 Configure the exec line configuration command on the line to allow exec sessions to be initiated. This command has no arguments or keywords. Example: The following example turns on the exec on line 7: line 7 exec
Flow control is not enabled, is enabled only on one device (either DTE or DCE), or is misconfigured	Step 1 Use the show line aux-line-number exec command and look for the following in the Capabilities field (see Figure 16-2): Capabilities: Hardware Flowcontrol In, Hardware Flowcontrol Out If there is no mention of hardware flow control in this field, hardware flow control is not enabled on the line. Hardware flow control for access server-to-modem connections is recommended. For an explanation of the output from the show line command, see the "Using debug Commands" section earlier in this chapter.
Flow control is not enabled, is enabled only on one device (either DTE or DCE), or is misconfigured	Step 2 Configure hardware flow control on the line using the flowcontrol hardware line configuration command. Example: The following example sets hardware flow control on line 7: line 7 flowcontrol hardware Note: If for some reason you cannot use flow control, limit the line speed to 9600 bps. Faster speeds are likely to result in lost data. Step 3 After enabling hardware flow control on the access server or router line, initiate a reverse Telnet session to the modem via that line. For more information, see the section "Establishing a Reverse Telnet Session to a Modem" earlier in this chapter. Step 4 Use a modem command string that includes the RTS/CTS Flow command for your modem. This command ensures that the modem is using the same method of flow control (that is, hardware flow control) as the Cisco access server or router. See your modem documentation for exact configuration command syntax. Figure 16-1 shows the hardware flow control command string for a Hayes-compatible modem.
Modem speed setting is not locked	Step 1 Use the show line exec command on the access server or router. The output for the auxiliary port should indicate the currently configured Tx and Rx speeds. For an explanation of the output of the show line command, see the "Using debug Commands" section earlier in this chapter.
Modem speed setting is not locked	Step 2 If the line is not configured to the correct speed, use the speed line configuration command to set the line speed on the access server or router line. Set the value to the highest speed in common between the modem and the access server or router port. To set the terminal baud rate, use the speed line configuration command. This command sets both the transmit (to terminal) and receive (from terminal) speeds. Syntax: speed bps Syntax Description: bps---Baud rate in bits per second (bps). The default is 9600 bps. Example: The following example sets lines 1 and 2 on a Cisco 2509 access server to 115200 bps: line 1 2 speed 115200 Note: If for some reason you cannot use flow control, limit the line speed to 9600 bps. Faster speeds are likely to result in lost data. Step 3 Use the show line exec command again and confirm that the line speed is set to the desired value. Step 4 When you are certain that the access server or router line is configured for the desired speed, initiate a reverse Telnet session to the modem via that line. For more information, see the section "Establishing a Reverse Telnet Session to a Modem" earlier in this chapter.
Modem speed setting is not locked	Step 5 Use a modem command string that includes the lock DTE speed command for your modem. See your modem documentation for exact configuration command syntax. Note: The lock DTE speed command, which might also be referred to as port rate adjust or buffered mode, is often related to the way in which the modem handles error correction. This command varies widely from one modem to another. Locking the modem speed ensures that the modem always communicates with the Cisco access server or router at the speed configured on the Cisco auxiliary port. If this command is not used, the modem reverts to the speed of the data link (the telephone line) instead of communicating at the speed configured on the access server.

Possible Causes	Suggested Actions
Modem configured for DCD always high	Step 1 The modem should be reconfigured to have DCD high only on CD. This is usually done with the &C1 modem command string (see Figure 16-1), but check your modem documentation for the exact syntax for your modem. Step 2 You might have to configure the access server line to which the modem is connected with the no exec line configuration command. Clear the line with the clear line privileged exec command, initiate a reverse Telnet session with the modem, and reconfigure the modem so that DCD is high only on CD. Step 3 End the Telnet session by entering disconnect and reconfigure the access server line with the exec line configuration command.
Modem control is not enabled on the access server or router	Step 1 Use the show line exec command on the access server or router. The output for the auxiliary port should show inout or RIisCD in the Modem column. This indicates that modem control is enabled on the line of the access server or router. For an explanation of the show line output, see the "Using debug Commands" section earlier in this chapter. Step 2 Configure the line for modem control using the modem inout line configuration command. Modem control is now enabled on the access server. Note: Be certain to use the modem inout command instead of the modem ri-is-cd command while the connectivity of the modem is in question. The latter command allows the line to accept incoming calls only. Outgoing calls will be refused, making it impossible to establish a Telnet session with the modem to configure it. If you want to enable the modem ri-is-cd command, do so only after you are certain the modem is functioning correctly.
Incorrect cabling	Step 1 Check the cabling between the modem and the access server or router. Confirm that the modem is connected to the auxiliary port on the access server or router with a rolled RJ-45 cable and an MMOD DB-25 adapter. This cabling configuration is recommended and supported by Cisco for RJ-45 ports. (These connectors are typically labelled "Modem.") There are two types of RJ-45 cabling: straight and rolled. If you hold the two ends of an RJ-45 cable side-by-side, you'll see eight colored strips, or pins, at each end. If the order of the colored pins is the same at each end, then the cable is straight. If the order of the colors is reversed at each end, then the cable is rolled. The rolled cable (CAB-500RJ) is standard with Cisco's 2500/CS500. Step 2 Use the show line exec command to verify that the cabling is correct. See the explanation of the show line command output in the section "Using debug Commands" earlier in this chapter.

Possible Causes	Suggested Actions
Modem speed setting is not locked	Step 1 Use the show line exec command on the access server or router. The output for the auxiliary port should indicate the currently configured Tx and Rx speeds. For an explanation of the output of the show line command, see the "Using debug Commands" section earlier in this chapter. Step 2 If the line is not configured to the correct speed, use the speed line configuration command to set the line speed on the access server or router line. Set the value to the highest speed in common between the modem and the access server or router port. To set the terminal baud rate, use the speed line configuration command. This command sets both the transmit (to terminal) and receive (from terminal) speeds. Syntax: speed bps Syntax Description: bps---Baud rate in bits per second (bps). The default is 9600 bps. Example: The following example sets lines 1 and 2 on a Cisco 2509 access server to 115200 bps: line 1 2 speed 115200 Note: If for some reason you cannot use flow control, limit the line speed to 9600 bps. Faster speeds are likely to result in lost data.
Modem speed setting is not locked	Step 3 Use the show line exec command again and confirm that the line speed is set to the desired value. Step 4 When you are certain that the access server or router line is configured for the desired speed, initiate a reverse Telnet session to the modem via that line. For more information, see the section "Establishing a Reverse Telnet Session to a Modem" earlier in this chapter. Step 5 Use a modem command string that includes the lock DTE speed command for your modem. See your modem documentation for exact configuration command syntax. Note: The lock DTE speed command, which might also be referred to as port rate adjust or buffered mode, is often related to the way in which the modem handles error correction. This command varies widely from one modem to another. Locking the modem speed ensures that the modem always communicates with the Cisco access server or router at the speed configured on the Cisco auxiliary port. If this command is not used, the modem reverts to the speed of the data link (the telephone line) instead of communicating at the speed configured on the access server.
Hardware flow control not configured on local or remote modem or router	Step 1 Use the show line aux-line-number exec command and look for the following in the Capabilities field (see Figure 16-2): Capabilities: Hardware Flowcontrol In, Hardware Flowcontrol Out If there is no mention of hardware flow control in this field, hardware flow control is not enabled on the line. Hardware flow control for access server-to-modem connections is recommended. For an explanation of the output of the show line command, see the section "Using debug Commands" earlier in this chapter.
Hardware flow control not configured on local or remote modem or router	Step 2 Configure hardware flow control on the line using the flowcontrol hardware line configuration command. To set the method of data flow control between the terminal or other serial device and the router, use the flowcontrol line configuration command. Use the no form of this command to disable flow control. Syntax: flowcontrol {none | software [lock] [in | out] | hardware [in | out]} Syntax Description: none---Turns off flow control. software---Sets software flow control. An optional keyword specifies the direction: in causes the Cisco IOS software to listen to flow control from the attached device, and out causes the software to send flow control information to the attached device. If you do not specify a direction, both are assumed. lock---Makes it impossible to turn off flow control from the remote host when the connected device needs software flow control. This option applies to connections using the Telnet or rlogin protocols. hardware---Sets hardware flow control. An optional keyword specifies the direction: in causes the software to listen to flow control from the attached device, and out causes the software to send flow control information to the attached device. If you do not specify a direction, both are assumed. For more information about hardware flow control, see the hardware manual that was shipped with your router. Example: The following example sets hardware flow control on line 7: line 7 flowcontrol hardware Note: If for some reason you cannot use flow control, limit the line speed to 9600 bps. Faster speeds are likely to result in lost data.
Hardware flow control not configured on local or remote modem or router	Step 3 After enabling hardware flow control on the access server or router line, initiate a reverse Telnet session to the modem via that line. For more information, see the section "Establishing a Reverse Telnet Session to a Modem." Step 4 Use a modem command string that includes the RTS/CTS Flow command for your modem. This command ensures that the modem is using the same method of flow control (that is, hardware flow control) as the Cisco access server or router. See your modem documentation for exact configuration command syntax. Figure 16-1 shows the hardware flow control command string for a Hayes-compatible modem.
Misconfigured dialer map commands	Step 1 Use the show running-config privileged exec command to view the router configuration. Check the dialer map command entries to see whether the broadcast keyword is specified. Step 2 If the keyword is missing, add it to the configuration. Syntax: dialer map protocol next-hop-address [name hostname] [broadcast] [dial-string] Syntax Description: protocol---The protocol subject to mapping. Options include IP, IPX1, bridge, and snapshot. next-hop-address---The protocol address of the opposite site's async interface. name hostname---A required parameter used in PPP authentication. It is the name of the remote site for which the dialer map is created. The name is case sensitive and must match the hostname of the remote router. broadcast---An optional keyword that broadcast packets (e.g., IP RIP or IPX RIP/SAP updates) to be forwarded to the remote destination. In static routing sample configurations, routing updates are not desired and the broadcast keyword is omitted.
Misconfigured dialer map commands	dial-string---The remote site's phone number. Any access codes (e.g., 9 to get out of an office, international dialing codes, area codes) must be included. Step 3 Make sure that dialer map commands specify the correct next hop addresses. Step 4 If the next hop address is incorrect, change it using the dialer map command. Step 5 Make sure all other options in dialer map commands are correctly specified for the protocol you are using. For detailed information on configuring dialer maps, refer to the Cisco IOS Wide-Area Networking Configuration Guide and Wide-Area Networking Command Reference.
Old PC UART problem	This problem only applies to PC-to-router dialin connections. Step 1 Use the terminal download command at the exec prompt before you Telnet. Step 2 If the problem persists, use the DOS program MSD to see what PC UART is on your comm port. Older PC UARTs, such as the 8250, can't run at speeds over 19200 bps. Step 3 If you have an older UART, try lowering your connection speed or get a faster serial card for your PC.
Problem with dialing modem	Make sure that the dialing modem is operational and is securely connected to the correct port. See whether another modem works when connected to the same port.

1IPX = Internetwork Packet Exchange

Possible Causes	Suggested Actions
IP routing not configured on local or remote router	Make sure that IP routing is enabled on the local and remote routers. For detailed information about configuring IP routing, refer to the Cisco IOS Network Protocols Configuration Guide, Part 1.
No default gateway specified on PC	Step 1 Use the show slip exec command and make sure that the specified IP address is the same as the default gateway specification on the PC. Step 2 Check the specified default gateway address on the PC. If the IP address is not correct, specify the correct address. For instructions on verifying and changing the default gateway address on the workstation, refer to the vendor documentation.
Hardware flow control not configured on local or remote modem or router	Step 1 Use the show line aux-line-number exec command and look for the following in the Capabilities field (see Figure 16-2): Capabilities: Hardware Flowcontrol In, Hardware Flowcontrol Out If there is no mention of hardware flow control in this field, hardware flow control is not enabled on the line. Hardware flow control for access server-to-modem connections is recommended. For an explanation of the output of the show line command, see the "Using debug Commands" section earlier in this chapter.
Hardware flow control not configured on local or remote modem or router	Step 2 Configure hardware flow control on the line using the flowcontrol hardware line configuration command. To set the method of data flow control between the terminal or other serial device and the router, use the flowcontrol line configuration command. Use the no form of this command to disable flow control. Syntax: flowcontrol {none | software [lock] [in | out] | hardware [in | out]} Syntax Description: none---Turns off flow control. software---Sets software flow control. An optional keyword specifies the direction: in causes the Cisco IOS software to listen to flow control from the attached device, and out causes the software to send flow control information to the attached device. If you do not specify a direction, both are assumed. lock---Makes it impossible to turn off flow control from the remote host when the connected device needs software flow control. This option applies to connections using the Telnet or rlogin protocols. hardware---Sets hardware flow control. An optional keyword specifies the direction: in causes the software to listen to flow control from the attached device, and out causes the software to send flow control information to the attached device. If you do not specify a direction, both are assumed. For more information about hardware flow control, see the hardware manual that was shipped with your router. Example: The following example sets hardware flow control on line 7: line 7 flowcontrol hardware Note: If for some reason you cannot use flow control, limit the line speed to 9600 bps. Faster speeds are likely to result in lost data.
Hardware flow control not configured on local or remote modem or router	Step 3 After enabling hardware flow control on the access server or router line, initiate a reverse Telnet session to the modem via that line. For more information, see the section "Establishing a Reverse Telnet Session to a Modem." Step 4 Use a modem command string that includes the RTS/CTS Flow command for your modem. This command ensures that the modem is using the same method of flow control (that is, hardware flow control) as the Cisco access server or router. See your modem documentation for exact configuration command syntax. Figure 16-1 shows the hardware flow control command string for a Hayes-compatible modem.
Misconfigured dialer map commands	Step 1 Use the show running-config privileged exec command to view the router configuration. Check the dialer map command entries to see whether the broadcast keyword is specified. Step 2 If the broadcast keyword is missing, add it to the configuration. For detailed information on configuring dialer maps, refer to the Cisco IOS Wide-Area Networking Configuration Guide and Wide-Area Networking Command Reference.
Static routes not configured	Step 1 Use the show ip route privileged exec command to see whether there is a static route to the remote network in the routing table. Step 2 If there is not a static route to the remote network, configure one using the ip route command. The static route should point to the remote network via the next hop in the dialer map. To establish static routes, use the ip route global configuration command. To remove static routes, use the no form of this command. Syntax: ip route prefix mask {address | interface} [distance] [tag tag] [permanent] Syntax Description: prefix---IP route prefix for the destination. mask---Prefix mask for the destination. address---IP address of the next hop that can be used to reach that network. interface---Network interface to use. distance---(Optional) An administrative distance. tag tag---(Optional) Tag value that can be used as a "match" value for controlling redistribution via route maps. permanent---(Optional) Specifies that the route will not be removed, even if the interface shuts down.
DNS1 server not specified on router or workstation	Step 1 Check to see whether the workstation and router both have DNS information specified. On the router, use the show running-config privileged exec command to see whether DNS is configured. For information on verifying the workstation configuration, refer to the vendor documentation. Step 2 If the router and workstation are not configured to use DNS, use the ip domain-lookup, ip domain-name, and ip name-server commands to configure the router. Example: The following example enables the IP DNS-based host name-to-address translation: ip domain-lookup Example: The following example defines cisco.com as the default domain name: ip domain-name cisco.com Example: The following example specifies host 131.108.1.111 as the primary name server and host 131.108.1.2 as the secondary server: ip name-server 131.108.1.111 131.108.1.2 This command is reflected in the configuration file as follows: ip name-server 131.108.1.111 ip name-server 131.108.1.2 Configure a DNS server address in the TCP/IP software on the PC. For more information, refer to the vendor documentation.

1DNS = Domain Name System

Possible Causes	Suggested Actions
IPX not enabled on the router	Make sure that IPX routing is enabled on the router. For detailed information on enabling IPX routing, refer to the Cisco IOS Network Protocols Configuration Guide, Part 1.
Incorrect Ethernet encapsulation	Step 1 Enter the show ipx servers privileged exec command on your router. If the router is not in the listing, the Ethernet encapsulation might be incorrect. Step 2 Configure the correct Ethernet encapsulation on the router's Ethernet port using the ipx network network encapsulation encapsulation-type interface configuration command. The encapsulation must be the same as on your server.
IPX stack not installed correctly on PC	This problem applies only to PC-to-router dialin connections. Make sure that the IPX software is properly installed on the PC. For more information on installing the IPX stack, refer to the vendor documentation.

Possible Causes	Suggested Actions
Modem is not sensing DTR	Enter the Hangup DTR modem command string. This command tells the modem to drop carrier when the DTR signal is no longer being received. On a Hayes-compatible modem the &D3 string is commonly used to configure Hangup DTR on the modem, as shown in Figure 16-1. For the exact syntax of this command, see the documentation for your modem.
Modem control is not enabled on the router or access server	Step 1 Use the show line exec command on the access server or router. The output for the auxiliary port should show inout or RIisCD in the Modem column. This indicates that modem control is enabled on the line of the access server or router. For an explanation of the show line output, see the "Using debug Commands" section earlier in this chapter. Step 2 Configure the line for modem control using the modem inout line configuration command. Modem control is now enabled on the access server. Note: Be certain to use the modem inout command instead of the modem ri-is-cd command while the connectivity of the modem is in question. The latter command allows the line to accept incoming calls only. Outgoing calls will be refused, making it impossible to establish a Telnet session with the modem to configure it. If you want to enable the modem ri-is-cd command, do so only after you are certain the modem is functioning correctly.

Possible Causes	Suggested Actions
Dialer timeout is too short	Step 1 Use the show running-config privileged exec command to view the router configuration. Check the value configured with the dialer idle-timeout command. Step 2 Increase the timeout value using the dialer idle-timeout seconds command. The default is 120 seconds.
Dialer lists are too restrictive	Step 1 Use the show running-config privileged exec command to view the router configuration. Check the access lists referenced by dialer list commands. Step 2 Make sure the access lists describe all the traffic that should keep the link active. Reconfigure the access lists to include additional traffic if necessary.

Possible Causes	Suggested Actions
Dialer lists not restrictive enough	Step 1 Use the show running-config privileged exec command to view the router configuration. Check the access lists referenced by dialer list commands. Step 2 Make sure the access lists do not describe traffic that should not keep the link active. Reconfigure the access lists to exclude uninteresting traffic if necessary.
Modems misconfigured	Make sure the local and remote modems are properly configured. In particular, both modems should be configured to disconnect on loss of DTR (Hangup DTR). On a Hayes-compatible modem the &D3 string is commonly used to configure Hangup DTR on the modem, as shown in Figure 16-1. For the exact syntax of this command, see the documentation for your modem.

Possible Causes	Suggested Actions
Error correction is not configured on the modem	Make certain the modem is configured for error correction. For the exact syntax of the command, see your modem documentation.
Flow control is not enabled, is enabled only on one device (either DTE or DCE), or is misconfigured	Step 1 Use the show line aux-line-number exec command and look for the following in the Capabilities field (see Figure 16-2): Capabilities: Hardware Flowcontrol In, Hardware Flowcontrol Out If there is no mention of hardware flow control in this field, hardware flow control is not enabled on the line. Hardware flow control for access server-to-modem connections is recommended. For an explanation of the output of the show line command, see the "Using debug Commands" section earlier in this chapter. Step 2 Configure hardware flow control on the line using the flowcontrol hardware line configuration command. To set the method of data flow control between the terminal or other serial device and the router, use the flowcontrol line configuration command. Use the no form of this command to disable flow control. Syntax: flowcontrol {none | software [lock] [in | out] | hardware [in | out]}
Flow control is not enabled, is enabled only on one device (either DTE or DCE), or is misconfigured	Syntax Description: none---Turns off flow control. software---Sets software flow control. An optional keyword specifies the direction: in causes the Cisco IOS software to listen to flow control from the attached device, and out causes the software to send flow control information to the attached device. If you do not specify a direction, both are assumed. lock---Makes it impossible to turn off flow control from the remote host when the connected device needs software flow control. This option applies to connections using the Telnet or rlogin protocols. hardware---Sets hardware flow control. An optional keyword specifies the direction: in causes the software to listen to flow control from the attached device, and out causes the software to send flow control information to the attached device. If you do not specify a direction, both are assumed. For more information about hardware flow control, see the hardware manual that was shipped with your router. Example: The following example sets hardware flow control on line 7: line 7 flowcontrol hardware Note: If for some reason you cannot use flow control, limit the line speed to 9600 bps. Faster speeds are likely to result in lost data. Step 3 After enabling hardware flow control on the access server or router line, initiate a reverse Telnet session to the modem via that line. For more information, see the section "Establishing a Reverse Telnet Session to a Modem."
Flow control is not enabled, is enabled only on one device (either DTE or DCE), or is misconfigured	Step 4 Use a modem command string that includes the RTS/CTS Flow command for your modem. This command ensures that the modem is using the same method of flow control (that is, hardware flow control) as the Cisco access server or router. See your modem documentation for exact configuration command syntax. Figure 16-1 shows the hardware flow control command string for a Hayes-compatible modem.
Congestion or line noise	Step 1 If the network is congested, dial-up connections can freeze for a few seconds. The only solution is to reduce congestion on the network by increasing bandwidth or redesigning the network. Step 2 Line noise can also freeze up a dialup connection. For information on how to account for line noise on your modem, refer to the vendor documentation.
Old PC UART	This problem applies only to PC-to-router dialin connections. Step 1 Use the DOS program MSD to see what PC UART is on your comm port. Older PC UARTs, such as the 8250, cannot run at speeds over 19200 bps. Step 2 If you have an older UART, try lowering your connection speed or get a faster serial card for your PC.