Introduction WAN Definitions
WAN Standards
WAN Architectures WAN Troubleshooting Targets DSUs versus CSUs
Cabling
Channel Service Unit/Digital Service Units (CSU/DSUs) Clocking Signal Encoding Framing Signaling CSU/DSU Alarms and Error Reports Loopback Testing
Router WAN Interfaces The Show Interface Command There Are No Collisions on Serial Interfaces! Troubleshooting Specific WAN Technologies
High-Level Data Link Control You've Been SLARPed Troubleshooting Cisco's HDLC
Point-to-Point Protocol (PPP) Troubleshooting PPP
Integrated Services Digital Network (ISDN) ISDN Layer 1 ISDN Layer 2 ISDN Layer 3 Troubleshooting ISDN SPID
Frame Relay Frame Relay Congestion Control Mapping Network Layer Addresses to DLCIs Frame Relay Local Management Interface LMI type vs. Encapsulation type Troubleshooting Frame Relay Conclusion