Chapter 09 - Net Testing

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NETWORK TESTING &NETWORK TESTING &

TROUBLESHOOTING TROUBLESHOOTING

TS, PHẠM VĂN TÍNHTS, PHẠM VĂN TÍNH

PART15PART15

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EXAMINING THE ROUTING TABLEEXAMINING THE ROUTING TABLE

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The show ip route CommandThe show ip route Command

The show ip route command displays the contents of the IP routing table. This table contains entries for all known networks and subnetworks, and a code that indicates how that information was learned.

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Determining the Gateway of Last ResortDetermining the Gateway of Last Resort

The term “gateway of last resort” includes the default route, default network, and default gateway.

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Determining Administrative DistanceDetermining Administrative Distance

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Determining the route metricDetermining the route metric

Routing protocols use metrics to determine the best route to a destination.

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NETWORK TESTINGNETWORK TESTING

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Five Steps TroubleshootingFive Steps Troubleshooting

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Typical Layer 1 ErrorsTypical Layer 1 Errors

Broken cables Disconnected cables Cables connected to the wrong

ports Intermittent cable connection Wrong cables used for the task at

hand (must use rollovers, crossover cables, and straight-through cables correctly)

Transceiver problems DCE cable problems DTE cable problems Devices turned of

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Improperly configured serial interfaces

Improperly configured Ethernet interfaces

Improper encapsulation set (HDLC is default for serial interfaces)

Improper clockrate settings on serial interfaces

Network interface card (NIC) problems

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Routing protocol not enabled

Wrong routing protocol enabled

Incorrect IP addresses

Incorrect subnet masks

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Troubleshooting Layer 1 using show Troubleshooting Layer 1 using show interfacesinterfaces

An increasing number of carrier transitions counts on a serial link may indicate one or more of the following problems: – Line interruptions due to problems in the service

provider network. – Faulty switch, DSU, or router hardware.

The following Layer 1 problems could be a cause of interface resets:– Bad line causing carrier transitions – Possible hardware problem at the CSU, DSU, or

switch If carrier transitions and interface resets are

increasing or if input errors are high while interface resets are increasing, the problem is likely to be a bad link or defective CSU or DSU.

Show

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Troubleshooting Layer 2 using show Troubleshooting Layer 2 using show interfacesinterfaces

If the interface is up and the line protocol is down, a Layer 2 problem exists. Among the possible causes are:

No keepalives

No clock rate

Mismatch in encapsulation type

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Troubleshooting routing issuesTroubleshooting routing issues

• Show ip route

• Show ip protocols

Show IP ROUTE & PROTOCOLS

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Troubleshooting using show controllers Troubleshooting using show controllers serialserial

Chapter 09 - Net Testing

Education

Transcript of Chapter 09 - Net Testing