System information

Troubleshooting Frame Relay Connections 18-403
Frame Relay: Frame Relay Link Is Down
Frame Relay: Frame Relay Link Is Down
Symptom: Connections over a Frame Relay link fail. The output of the show interfaces serial exec
command shows that the interface and line protocol are down or that the interface is up and the line
protocol is down.
Table 18–1 outlines the problems that might cause this symptom and describes solutions to those
problems.
Table 18-1 Frame Relay: Frame Relay Link Is Down
Possible Problem Solution
Cabling, hardware, or carrier
problem
Perform these steps for the local and remote router:
Step 1 Use the show interfaces serial command to see whether the interface and
line protocol are up.
Step 2 If the interface and line protocol are down, check the cable to make sure it
is a DTE
1
serial cable. Make sure cables are securely attached.
Step 3 If the cable is correct, try moving it to a different port. If that port works,
then the first port is defective. Replace either the card or the router.
Step 4 If the cable doesn’t work on the second port, try replacing the cable. If it
still doesn’t work, there might be a problem with the DCE
2
. Contact your
carrier about the problem.
For detailed information on troubleshooting serial lines, refer to Chapter 15,
“Troubleshooting Serial Line Problems.”
LMI
3
type mismatch Step 1 Use the show interfaces serial command to check the state of the
interface.
Step 2 If the output shows that the interface is up but the line protocol is down,
use the show frame-relay lmi exec command to see which LMI type is
configured on the Frame Relay interface.
Step 3 Make sure that the LMI type is the same for all devices in the path from
source to destination. Use the frame-relay lmi-type {ansi | cisco | q933a}
interface configuration command to change the LMI type on the router.
Keepalives not being sent
Step 1 Enter the show interfaces command to find out whether keepalives are
configured. If you see a line that says “keepalives not set,” keepalives are
not configured.
Step 2 Use the keepalive seconds interface configuration command to configure
keepalives. The default value for this command is 10 seconds.
Encapsulation mismatch Step 1 When connecting Cisco devices with non-Cisco devices, you must use
IETF
4
encapsulation on both devices. Check the encapsulation type on the
Cisco device with the show frame-relay map exec command.
Step 2 If the Cisco device is not using IETF encapsulation, use the encapsulation
frame-relay ietf interface configuration command to configure IETF
encapsulation on the Cisco Frame Relay interface.
For information on viewing or changing the configuration of the non-Cisco device,
refer to the vendor documentation.