3Com 10014299 manual Fault Diagnosis Troubleshooting Frame Relay

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-infois 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.