how to observe lost packets on router?

Unanswered Question
Aug 5th, 2009

Hi :)

guys i need some help please

I was asked to observe the following information on two core routers (CISCO 3560G-48TS-E, each router is connected to 3 remote routers)and prepare an analyze report based on:

- Lost packets

- Dropped Packets

- CPU load

- Any other information could be good for that kind of analyze report.

which command should i use to get those information?

i am suppose to get the above mentioned information for 12 hours.

if there is a command that shows what we want, i am planning to run that command once a hour for 12 hours and prepare a graphics.

any suggestion will be appreciated.

#show controllers command shows something. but is there a better way?

tx in advance for helping :)


I have this problem too.
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Wilson Samuel Wed, 08/05/2009 - 05:01

Hi Alfonzo,

The simplest way to get this info is to use the following commands:

1. sh interface (on the interfaces connected to the remote routers)

2. sh cpu proc history

These would be a very good to begin with.

Also, do you have LMS (or any other SNMP Manager) in your network, if yes, please try to you that, otherwise, you may download SolarWinds (Eval edition, and if you find ok, you may purchase lic.) or if you are a Linux fan, MRTG would be also a great bet.

Please rate, if helpful


Wilson Samuel

alfonzofernando Wed, 08/05/2009 - 07:10

Hi Wilson :)

Tx a lot for your helpful inforrmation. Does sh interface comman shows the packet lost?

bad point is ı've got only one day in the site (where the routers are) and i dont have time learn using LMS kind of programs.

CLI commands would be much better. i guess "sh int" commands tells about lost/dropped packets ?

mbroberson1 Wed, 08/05/2009 - 05:05

Hi Alfonzo,

I would use a FREE program like Cacti and let it go to work for you. You may even consider using it on a permanent basis. You will like it.



yagnesh_tel Wed, 08/05/2009 - 05:21


You can use SNMP based tool to monitor device performance. This is the most convenient way to get these data from router. There are plenty of these tools available on web(some are free).Just allow snmp polling from this tool in your router and tool will give you data in graphical manner without issuing command on router.

Or else use following command to get the data from your router itself.

sh proc cpu history - use this command to get CPU load

sh interface - use this command on your interfaces to see any error/discard/drops

alfonzofernando Wed, 08/05/2009 - 09:21

thanks a lot!

i think whatever GUI i use(like LMS), they won't get me anythink more than i can get from CLI right? bcs i have only one day on site and have no time to learn using that program. i am familiar with CLI so i prefer to use commands you gave me.

#sh proc cpu history

does it show time information of CPU ?

yagnesh_tel Thu, 08/06/2009 - 05:04

sh proc cpu history can give avarage and maximum CPU utilization for the period of 60 sec,60 min & 72 hours. Also for the lost(drop) packets, you can see input and output drop on interface using 'sh int ' command.


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