System information

Troubleshooting Dialin Connections 16-363
Dialin: Modem Cannot Send or Receive IP Data
Dialin: Modem Cannot Send or Receive IP Data
Symptom: After a dialin connection is established, a modem cannot send or receive IP data.
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,
IPX
1
, 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.
1 IPX = Internetwork Packet Exchange
Possible Causes Suggested Actions