Hi
If your looking to limit bandwidth traffic per subnet range use MQC qos , example below , create the class-map and policy-map and then apply to the WAN interface of the 1841
http://www.cisco.com/c/en/us/td/docs/ios/qos/configuration/guide/12_2sr/qos_12_2sr_book/qos_mqc.html#wp1059593
Configuration Examples for Applying QoS Features Using the MQC
Example: Creating a Traffic Class
In the following example, two traffic classes are created and their match criteria are defined. For the first traffic class called class1, access control list (ACL) 101 is used as the match criterion. For the second traffic class called class2, ACL 102 is used as the match criterion. Packets are checked against the contents of these ACLs to determine if they belong to the class.
Router(config)# class-map class1
Router(config-cmap)# match access-group 101
Router(config-cmap)# exit
Router(config)# class-map class2
Router(config-cmap)# match access-group 102
Router(config-cmap)# exit
Example: Creating a Traffic Policy
In the following example, a traffic policy called policy1 is defined. The traffic policy contains the QoS features to be applied to two classes—class1 and class2. The match criteria for these classes were previously defined (as described in the "Example: Creating a Traffic Class").
For class1, the policy includes a bandwidth allocation request and a maximum packet count limit for the queue reserved for the class. For class2, the policy specifies only a bandwidth allocation request.
Router(config)# policy-map policy1
Router(config-pmap)# class class1
Router(config-pmap-c)# bandwidth 3000
Router(config-pmap-c)# queue-limit 30
Router(config-pmap-c)# exit
Router(config-pmap)# class class2
Router(config-pmap-c)# bandwidth 2000
Router(config-pmap-c)# exit
Example: Attaching a Traffic Policy to an Interface
The following example shows how to attach an existing traffic policy to an interface. After you define a traffic policy with the policy-map command, you can attach it to one or more interfaces by using the service-policy command in interface configuration mode. Although you can assign the same traffic policy to multiple interfaces, each interface can have only one traffic policy attached in the input direction and only one traffic policy attached in the output direction.
Router(config)# interface ethernet1/1
Router(config-if)# service-policy output policy1
Router(config)# interface fastethernet1/0/0
Router(config-if)# service-policy output policy1
