Chap 13 Network Chap 13 Network TroubleshootingTroubleshooting

Andres, Wen-Yuan Liao

Department of Computer Science and Engineering

De Lin Institute of Technology

andres@dlit.edu.tw

http://www.cse.dlit.edu.tw/~andres

Troubleshooting NetworkTroubleshooting Network

Describe typical layer 1 errors Typical layer 2 errors Typical layer 3 errors Network troubleshooting

strategies

Problems in each layerProblems in each layer

Layer 1 - incorrect cable used Layer 2 - interface not

configured for Ethernet Layer 3 - subnet mask is

incorrect

Describe typical layer 1 errorsDescribe typical layer 1 errors

Broken cables Disconnected cables Cables connected to the wrong

ports Intermittent cable connectionDevices turned off

Describe typical layer 1 errorsDescribe typical layer 1 errors

Wrong cables used for the task at hand (must use rollovers, cross-connects, and straight-through cables correctly)

Transceiver problems DCE cable problems DTE cable problems

Typical layer 2 errorsTypical layer 2 errors

Improperly configured serial interf. Improperly configured Ethernet interfa

ces Improper encapsulation set (HDLC is

default for serial interfaces) Improper clockrate settings on serial i

nterfaces

Typical layer 3 errorsTypical layer 3 errors

Routing protocol not enabled Wrong routing protocol

enabled Incorrect IP addresses Incorrect Subnet Masks Incorrect DNS to IP bindings

SummarySummary Layer 1 errors Layer 2 errors Layer 3 errors Network Problems