Ch 13 Network Troubleshooting Laboratorium Telematika ITB Cisco

Ch 13. Network Troubleshooting Laboratorium Telematika - ITB Cisco Regional Networking Academy Semester 2 Version 2. 1 Duration: 60 minutes

Overview n Errors and their cause u Layer 1 u Layer 2 u Layer 3 n Troubleshooting tools

Layer 1 Errors n Devices turned off u Turn n it on! Disconnected cable u Connect n Cable connected to the wrong port u Move n the cable Wrong cable type (check visually or with a cable tester) u Change n the cable Broken cable (test with a cable tester) u Change cable

Layer 1 Errors (cont) n Intermittent cable connection u Check connectors and change cable if necessary n Transceiver problem u Service the device

Layer 2 Errors n Improperly configured serial interface u Reconfigure n Improperly configured Ethernet interface u Reconfigure; make sure it uses the correct media-type n Improper encapsulation set u Check that all devices on the network uses the same encapsulation (e. g. , HDLC for serial, ARPA for Ethernet) n Improper clock rate settings u Matters only when router is DCE and not connected to another router

Layer 3 Errors n Routing not enabled u Check for the presence of ip routing command (or, absence of no ip routing command) n No routing protocol enabled u Activate the routing protocol with the router protocol command n Wrong routing protocol u Disable the wrong protocol with no router protocol command u Activate the right protocol with router protocol command

Layer 3 Errors (cont) n Incorrect IP address u IP address on an interface must be part of the subnet connected to the interface n Incorrect subnet mask u All devices on a subnet must have the same subnet mask n Presence of static routing u Remove static routing

Troubleshooting Resources n n n n Team members — someone with more experience Journals — yours and your colleagues’ Experts IOS Help & Cisco Documentation Web resources Troubleshooting tools Troubleshooting strategies

Troubleshooting Tools n n n Multimeter Cable tester Protocol Inspector Network Inspector Router commands: u ping u trace u show cdp neighbor u show ip route u show run

OSI Layer Troubleshooting n n n It is best to start troubleshooting at layer 1. Then proceed upward through the layers. Very often difficult problems turn out to be Layer 1 issues. u Usually, troubleshooting internetworking devices is limited to layers 1, 2, and 3.

5 Step Troubleshooting 1. Collect all available information u Analyze symptoms of failure 2. Localize the problem u Segment, module/unit, user 3. Isolate the trouble u Specific hardware or software 4. Locate and correct the problem u If necessary, repair and replace 5. Verify that the problem has been solved u If not, restart procedure and find other likely culprit

The End