Bandwidth limiting,CB Policing clarification.

vlatkorun · ‎02-27-2009

This is a lab enviroment.The network diagram is in the attachment.PC1 is in Vlan2.The Cisco router has a default route set:

ip route 0.0.0.0 0.0.0.0 192.168.1.1.

I want to limit the bandwidth, input & output, on Vlan 2 interface to 2 Mbps only.

My configuration:

#policy-map bandwidth_limit

#class class-default

#police 2000000 conform-action transmit exceed-action drop

#int vlan 2

#service-policy input bandwidth_limit

#service-policy output bandwidth_limit

Now, as i understanded well what does CB Policing does, traffic from PC1 if does not exceed 2Mbps will be transmited

and packets that exceed 2Mbps will be droped,having this configuration on the router.

I use the Wan Killer utility, from SolarWinds Engineer Toolset, to generate 7Mbps from PC1(this info is from Network Limiter Bandwidth Monitor) traffic(UDP 7 Echo segments)to destination IP 192.168.1.1.

When I run #show int vlan 2 :

5 minute input rate 4147000 bits/sec,410 packets/sec

5 minute output rate 144000 bits/sec, 14 packets/sec

Shouldn't the input rate be below 2000000(2Mbps) because of the policing configured od the interface?

Giuseppe Larosa · ‎02-27-2009

Hello Vladimir,

try to apply the same commands directly on interface fas2.

Hope to help

Giuseppe

vlatkorun · ‎03-01-2009

Thanks for your suggestion, I tried to apply on fastethernet 2 but the result was the same.

I am realy want to know how can I conclude that the policing works,with which command,output etc., I can see the results.

chuckwirth · ‎03-03-2009

Try:

show policy-map interface vlan #

or

show policy-map interface #

How to interpret counters:

http://www.cisco.com/en/US/tech/tk543/tk760/technologies_tech_note09186a0080108e2d.shtml

Joseph W. Doherty · ‎02-27-2009

"Shouldn't the input rate be below 2000000(2Mbps) because of the policing configured od the interface? "

Not for much non-TCP traffic, such as the UDP you're testing with. Even with TCP, the offered rate can be higher than the policed rate.