Module : Layer 2 Troubleshooting
Module Overview
Characteristics of Data Link Layer Problems
Data link layer problems overview
No component above the data link layer is functional
The network is functional, but operating at less than the baseline level
Framing errors
Encapsulation errors
Layer 2 to Layer 3 address mapping errors
Critical characteristics – no network layer connectivity
Upper layer component operation
Critical characteristics – console messages
Troubleshooting Switched Ethernet Networks
Troubleshooting the Spanning Tree Protocol
Troubleshooting STP loops
Preventing STP loops
Troubleshooting incorrect STP root configuration
Troubleshooting Ethernet broadcast traffic
Troubleshooting Ethernet switch flooding
Troubleshooting VTP misconfiguration
Troubleshooting EtherChannel
Troubleshooting Gateway Redundancy Protocols
Gateway redundancy
HSRP configuration and verification
How to debug HSRP operations
Troubleshooting ISDN
T1 framing errors
Troubleshooting ISDN primary rate switch types
Troubleshooting ISDN BRI to telco communications
Troubleshooting ISDN BRI dialer problems
Debugging ISDN call setup failures
Troubleshooting Frame Relay
Steps for troubleshooting Frame Relay
The show frame-relay lmi command
The show frame-relay pvc command
Frame Relay encapsulation type
Troubleshooting Frame Relay using the line status
Ping the local IP address on a multipoint Frame Relay
Reconfiguring a subinterface
PPP and Layer 2 Considerations for Routed and Routing Protocols
Link Control Protocol
Troubleshooting PPP authentication PAP
Troubleshooting PPP authentication CHAP
IP split horizon checking
OSPF in an NBMA environment
The keyword broadcast
Excessive fragmentation
Module: Summary
Module: Quiz



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