Troubleshoot slow Internet connection / Cisco router commands

eddo9696 used Ask the Experts™
For the past few days our internet connection has been running unusually slow. Telekom claims that we are using our full bandwidth. I find this hard to believe but would like to verify what we are using. Does anyone know which commands I can use for a Cisco router to find this information?
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At a glance (using the Telekom interface):

sh int

Look for 5 minute input and output

I would recommend installing either MRTG or Cacti (both are free and both run on Linux or Windows) to monitor your utilization.  You could also consider PRTG but that is a commercial product.
You can enable the netflow feature in Cisco router and use the command

sh ip cache flow

to enable the netflow in your cisco router use the following example

Router#conf  t
Router(config)# int <use your wan interface>
Router(config-if)# ip flow ingress
Router(config-if)# exit
Router(config)# int <use your LAN interface>
Router(config-if)# ip flow ingress
Router(config-if)# exit

Now if you are planning to use a computer setup with a netflow collector you should use the following commands

Router(config)# ip flow-export sour lo 0
Router(config)# ip flow-export  ver 5
Router(config)# ip flow-export  destination <your collector PC IP address>  5000

5000 is the UDP port number to be used by the netflow.

again.. if you do not intend to use a PC as a collector you can still get the info you need by using the command

Router# sh ip cache flow

Oh, by the way, the reason why I told you to monitor both the WAN and LAN interfaces is to get a better picture about the utilization of your network resources.



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