Fault Diagnosis and Troubleshooting of Frame Relay 285
Fault Diagnosis and Troubleshooting of Frame Relay
Fault 1: the physical layer in DOWN status.
Troubleshooting:
■Check whether the physical line is normal.
■Check whether the opposite equipment runs normally.
Fault 2: the physical layer is already UP, but the link layer protocol is
DOWN.
Troubleshooting:
■Check whether both local equipment and opposite equipment have been
configured with Frame Relay protocol.
■If two sets of equipment are directly connected, check the local equipment and
opposite equipment to see whether one end is configured as Frame Relay DTE
interface and the other end as Frame Relay DCE interface.
■Turn on the monitoring switch for the Frame Relay LMI packet to see whether
the Status Enquiry packets correspond to the Status packet. If not, it indicates
the physical layer data is not receiving or sending correctly. Check the physical
layer. Command debugging fr lmi-info is used to turn on the monitoring
switch for Frame Relay LMI information.
Fault 3: link layer protocol is UP, but cannot Ping through the peer.
Troubleshooting:
■Check whether the link layer protocols of the equipment at both ends are UP.
■Check whether the equipment at both ends have configured (or created)
correct address mapping for the peer.
■Check the route table to see whether there is a route to the peer.
Fault 4: After the Frame Relay traffic shaping is enabled on the Frame
Relay interface, the small-sized packets can be pinged, but the large-sized
packets cannot.
Troubleshooting:
■Configuring a too small committed burst size (CBS) will probably cause this
phenomenon. In common conditions, CBS cannot be less than 12000 bits. If it
is configured too small, the large packets will probably fail to be transmitted.
■Check the configurations of the Frame Relay class associated with the Frame
Relay interface or the PVCs, and use the fr cbs command to make the CBS
larger.
Fault 4: Frame Relay data cannot be transmitted across ISDN.
Troubleshooting:
■Check whether BDR has been correctly configured. Read the section of
troubleshooting in Dial-up.
■Use the debugging dialer event command to enable BDR event debugging.
If “BDR: Bind failed with more than one profile” is displayed, it means that the
dialer number command has been configured repeatedly at the receiving
end. In this case, make sure that this command is uniquely configured at the
receiving end.