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Troubleshooting Serial Lines

383

Last input 00:00:08, output 00:00:07, output hang never

Last clearing of "show interface" counters never

Input queue: 0/75/0 (size/max/drops);

Total output drops: 0

Queueing strategy: weighted fair

Output queue: 0/1000/64/0 (size/max total/threshold/
drops)

Conversations 0/1/256 (active/max active/max total)

Reserved Conversations 0/0 (allocated/max allocated)

5 minute input rate 0 bits/sec, 0 packets/sec

5 minute output rate 0 bits/sec, 0 packets/sec

1307 packets input, 85380 bytes, 0 no buffer

Received 695 broadcasts, 0 runts, 0 giants, 0
throttles

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored,

0 abort

1308 packets output, 85652 bytes, 0 underruns

0 output errors, 0 collisions, 116 interface resets

0 output buffer failures, 0 output buffers swapped

out

238 carrier transitions

DCD=up DSR=up DTR=up RTS=up CTS=up

Router_A>

The output tells you that the interface is up and the line protocol is

also up. The information contained in the

show interface serial

command will be discussed in more detail in just a moment. For now, it is
important to recognize that many of the counters have elevated numbers.
Also, notice that the seventh line of the output declares that the counters
were never cleared.

You cannot effectively troubleshoot if you do not have accurate data

returned through the many diagnostic commands. One way to ensure
that the data you are analyzing is accurate and directly applies to the prob-
lem at hand is to perform the

clear counters serial

number>

com-

mand, which resets the interface counters to zero. This ensures that the data
retrieved from the

interface

command is representative of what is happen-

ing at that moment on the network.

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