show int command on switch

Answered Question
May 23rd, 2010

Hi every body.

I just want to know   when we use the command "  show int "  on a cisco switch,   it will show different counters such as input error ,output error,  etc.

What are input error and output error? 

what is considered as input  and output?

thanks and have a nice weekend.

I have this problem too.
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Correct Answer by Leo Laohoo about 6 years 6 months ago

This command is not applicable to the 2900/3500XL, 4XXX and 6XXX.  Try the command "sh controller ethernet " for a refine output.

Correct Answer by Reza Sharifi about 6 years 6 months ago

Hi Sarah,

There are a number things that can cause input and output errors. Example:

By default, all layer 2 ports are in dynamic desirablemode, so the layer 2 port tries to form a trunk link and sends out DTP packets to the remote device. When a layer 3 interface is connected to a layer 2 switchport, it is not able to interpret these frames, which results in Input errors, WrongEncap errors, and Input queue drops.

Have a look at this document for more info:

http://www.cisco.com/en/US/products/hw/switches/ps700/products_tech_note09186a008015bfd6.shtml#intro

HTH

Reza

Correct Answer by Giuseppe Larosa about 6 years 6 months ago

Hello Sarah,

input packets = valid packets received on the interface

output packets = valid packets transmitted successfully on the interface

input errors are errors in receiving packets, specific error types apply to different interface type (serial, ATM, fastethernet)

output errors are errors in sending packets out the interface.

for ethernet interfaces you can look at:

see the description of all fields here:

http://www.cisco.com/en/US/docs/internetworking/troubleshooting/guide/tr1904.html

http://www.cisco.com/en/US/products/hw/switches/ps700/products_tech_note09186a008015bfd6.shtml

among input errors there are:

giants : frames  too big to be received

runts: frames too short (minimum size is 64 bytes in ethernet)

CRC : FCS checksum fails

possible output errors include collisions, late collisions, multiple collisions

Hope to help

Giuseppe

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Correct Answer
Giuseppe Larosa Sun, 05/23/2010 - 12:45

Hello Sarah,

input packets = valid packets received on the interface

output packets = valid packets transmitted successfully on the interface

input errors are errors in receiving packets, specific error types apply to different interface type (serial, ATM, fastethernet)

output errors are errors in sending packets out the interface.

for ethernet interfaces you can look at:

see the description of all fields here:

http://www.cisco.com/en/US/docs/internetworking/troubleshooting/guide/tr1904.html

http://www.cisco.com/en/US/products/hw/switches/ps700/products_tech_note09186a008015bfd6.shtml

among input errors there are:

giants : frames  too big to be received

runts: frames too short (minimum size is 64 bytes in ethernet)

CRC : FCS checksum fails

possible output errors include collisions, late collisions, multiple collisions

Hope to help

Giuseppe

sarahr202 Sun, 05/23/2010 - 17:05

http://http://www.cisco.com/en/US/products/hw/switches/ps700/products_tech_note09186a008015bfd6.shtml

Thanks Giuseppe  .  The above forwarded link   shows"  no buffer""  and  " ignored"   counters   when " show int" command is issued.   I  still do not understand the difference between the two counters.   Would you please explain the difference?

Thanks  and have a nice weekend.

Correct Answer
Reza Sharifi Sun, 05/23/2010 - 12:48

Hi Sarah,

There are a number things that can cause input and output errors. Example:

By default, all layer 2 ports are in dynamic desirablemode, so the layer 2 port tries to form a trunk link and sends out DTP packets to the remote device. When a layer 3 interface is connected to a layer 2 switchport, it is not able to interpret these frames, which results in Input errors, WrongEncap errors, and Input queue drops.

Have a look at this document for more info:

http://www.cisco.com/en/US/products/hw/switches/ps700/products_tech_note09186a008015bfd6.shtml#intro

HTH

Reza

Correct Answer
Leo Laohoo Sun, 05/23/2010 - 15:21

This command is not applicable to the 2900/3500XL, 4XXX and 6XXX.  Try the command "sh controller ethernet " for a refine output.

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