Verifying your cisco Router configuration with the Show Interface Command.

Verifying your cisco router configuration

 

available interfaces to configure. The only cisco router interfaces that are not logical are Ethernet and Serial.

Router#sh int ?

Ethernet IEEE 802.3

Null Null interface

Serial Serial

accounting Show interface accounting

crb Show interface routing/bridging information

irb Show interface routing/bridging information

<cr>

The next command is show interface ethernet 0 and shows us the hardware

address, logical address, and encapsulation method, as well as statistics

on collisions.

Router#sh int e0

Ethernet0 is up, line protocol is up

Hardware is Lance, address is 0010.7b7f.c26c (bia

0010.7b7f.c26c)

Internet address is 192.168.88.2/24

MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec,

reliability 255/255, txload 1/255, rxload 1/255

Encapsulation ARPA, loopback not set, keepalive set (10

sec)

ARP type: ARPA, ARP Timeout 04:00:00

Last input 00:08:23, output 00:08:20, output hang never

Last clearing of “show interface” counters never

Queueing strategy: fifo

Output queue 0/40, 0 drops; input queue 0/75, 0 drops

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

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

25 packets input, 2459 bytes, 0 no buffer

Received 25 broadcasts, 0 runts, 0 giants, 0 throttles

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

0 abort

0 input packets with dribble condition detected

33 packets output, 7056 bytes, 0 underruns

0 output errors, 0 collisions, 1 interface resets 0 babbles, 0 late collision, 0 deferred

0 lost carrier, 0 no carrier 0 output buffer failures, 0 output buffers swapped out

The most important status of the show interface command is the output

of the line and data-link protocol status. If Ethernet 0 is up, line protocol

is up, and the line is up and running.

 

RouterA#sh int e0

The output will be the following

Ethernet0 is up, line protocol is up

The first parameter refers to the Physical layer and is up when it receives carrier

detect.

The second parameter refers to the Data Link layer and looks for keepalives from the connecting end.

verifying the cisco Serial Interface configuration

RouterA#sh int s0

Serial0 is up, line protocol is down

If you see the line is up, but the protocol is down, you are having a clocking

(keepalive) or framing issue. Check the keepalives on both ends to make

sure they match; the clock rate is set, if needed; and the encapsulation type

is the same on both ends.

 

RouterA#sh int s0

Serial0 is down, line protocol is down

If you see the line interface and protocol down, it is a cable or interface problem.

Also, if one end is administratively shut down, then the remote end

would show down and down. To turn on the interface, type the command no

shutdown in interface configuration.

 

RouterB#sh int s0

Serial0 is administratively down, line protocol is down

The next command demonstrates the serial line and the Maximum Transmission

Unit (MTU), which is 1500 bytes by default. It also shows the

default bandwidth (BW) on all Cisco serial links: 1.544Kbs. This is used to

determine the bandwidth of the line for routing protocols such as IGRP,

EIGRP, and OSPF. Another important configuration to notice is the keepalive,

which is 10 seconds by default. Each router sends a keepalive message

to its neighbor every 10 seconds.

If both routers are not configured for the same keepalive time, it will not work.

You can clear the counters on the interface by typing the command clear counters.

 

Router#sh int s0

Serial0 is up, line protocol is up

Hardware is HD64570

MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,

reliability 255/255, txload 1/255, rxload 1/255

Encapsulation HDLC, loopback not set, keepalive set (10 sec)

Last input never, output never, output hang never

Last clearing of “show interface” counters never

Queueing strategy: fifo

Output queue 0/40, 0 drops; input queue 0/75, 0 drops

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

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

0 packets input, 0 bytes, 0 no buffer

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

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort 0 packets output, 0 bytes, 0 under runs

0 output errors, 0 collisions, 16 interface resets 0 output buffer failures, 0 output buffers swapped out 0 carrier transitions

DCD=down DSR=down DTR=down RTS=down CTS=down

 

Router#clear counters ?

Ethernet IEEE 802.3

Null Null interface

Serial Serial

<cr>

 

Router#clear counters s0

Clear “show interface” counters on this interface

[confirm]return

Router#

 

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