Troubleshooting Frame Relay
403
Troubleshooting Frame Relay
F
rame Relay is a popular WAN solution in many networks. Frame
Relay supports PVCs and switched virtual circuits (SVCs). These virtual
circuits are built by using DLCI numbers. A Data-Link Connection
Identifier (DLCI) is used to identify the virtual circuits in a Frame Relay
cloud. Figure 7.3 depicts a Frame Relay network. Notice the DLCI
numbers assigned to the different interfaces throughout the network.
F I G U R E 7 . 3
Frame Relay network
It is important to remember that the DLCI is only locally significant.
The DLCI maps to Layer 3 IP addresses, as shown in Figure 7.3. The IP
addresses given on the diagram suggest the PVCs that exist through the
Frame Relay cloud.
When Frame Relay problems occur, you follow this troubleshooting checklist:
1.
Check Layer 1, the Physical layer, for any cabling or interface problems.
2.
Check the interface encapsulation.
3.
Check the LMI type.
4.
Verify the DLCI-to-IP address mapping.
Copyright ©2000 SYBEX , Inc., Alameda, CA
www.sybex.com