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frede_frede
Beginner

Limit the bandwidth 3750

Hi,

I would like to limit the bandwidth available to a different target machine. I have been trying to do this on a cisco 3750, but first I came across this message:

% QoS: policy-map with police action at parent level not supported ...

Then this:

% QoS: policy-map child ... ClassMap BackLimit only support MATCH-INPUT INTERFACE

Is there any documentation that can help me, I searched the forum but all I see are complex solutions, I just wanted to limit the bandwidth for a machine that is in a different site. I wanted to apply the policy on an interface SVI.

greetings

Fred

8 REPLIES 8

Frederico Fred wrote:

Hi,

I would like to limit the bandwidth available to a different target machine. I have been trying to do this on a cisco 3750, but first I came across this message:

% QoS: policy-map with police action at parent level not supported ...

Then this:

% QoS: policy-map child ... ClassMap BackLimit only support MATCH-INPUT INTERFACE

Is there any documentation that can help me, I searched the forum but all I see are complex solutions, I just wanted to limit the bandwidth for a machine that is in a different site. I wanted to apply the policy on an interface SVI.

greetings

Fred

Hello Fred,

Check out the below link for Qos for cisco 3750

http://www.cisco.com/en/US/products/hw/switches/ps5023/products_tech_note09186a0080883f9e.shtml

Hope to Help !!

Ganesh

rate if it helps

nkarthikeyan
Rising star

Hi,

thanks for the help.

I have one doubt in the police-map configuration, for example:

police 10000000 8000 exceed-action drop

the first value (10000000) is about what? And the second?

How can I drop the traffic if this exceded 30 mbps, for example

It's possible to overtake the limit to aply the police in the outbound traffic?

thanks to all

Hello,

  • police 10000000 8000 exceed-action drop

In this command, you are policing the user traffic to 10 Mb and giving 8000 bytes burst.

You can assign burst size with any police so it wont drop the packet straight way

after reaching to police limit. In short cut, it is a bit extra bandwidth for the queue

before it actually drops the packet.

It is always good to have some burst so packets will not drop soon in congested network.

Burst—defines the maximum amount of tokens the bucket can hold at any time. Supported

bursts range from 8000 bytes to to 2000000 bytes, and increment by 64 bytes

Hope this will help.

thanks

thanks

and about the limit to apply the police in the outbound traffic? It's possible to overtake?

Yes, you can apply it outbound as well. However, the policy will only kicks in if there is congestion on the interface and will start dropping packets.

Thanks

Hi Amrinder,

but the Catalyst 3750 doesn't support the command, when i apply the police in the outbound traffic I have this message

police command is not supported for this interface

Configuration failed!

Warning: Assigning a policy map to the output side of an interface not supported

thanks

Fred

thats because you have to apply a policy map to the input side. Egress(output) from the port to the computer. Ingress(Input) from the computer to the port.

at the port:

srr-queue bandwidth limit 53 (53% of port bandwidth in this case 10Mbps means a little more than 5 Mbps makes it through)

then for the Ingress create a policy map and apply to the same port:

policy-map limit-upload
class class-default
police 2000000 200000 exceed-action drop

the actual police action here is to limit upload speeds to 2 Mbps. so the port looks like this

interface FastEthernet0/1

 switchport mode access
 speed 10
 srr-queue bandwidth limit 53
 service-policy input limit-upload

 

 

Doing a speed test from the computer shows 5Mbps download and 2Mbps upload. This is why I say the terminology is backward for the port side (switch side)