Policing
When an interface becomes congested and packets start to queue, you can apply a queuing method to packets waiting to be transmitted. Cisco IOS logical interfaces do not inherently support a state of congestion and do not support the direct application of a service policy that applies a queuing method. Instead, you need to apply a hierarchical policy as follows:
Create a "child" or lower-level policy that configures a queueing mechanism, such as low latency queueing with the priority command and class-based weighted fair queueing (CBWFQ) with the bandwidth command. See Congestion Management for more information.
policy-map child
class voice
priority 512Create a "parent" or top-level policy that applies class-based shaping. Apply the child policy as a command under the parent policy since admission control for the child class is done based on the shaping rate for the parent class.
policy-map tunnel
class class-default
shape average 2000000
service-policy child Apply the parent policy to the tunnel interface.
interface tunnel0
service-policy tunnelThe router prints the following log message when a tunnel interface is configured with a service policy that applies queuing without shaping.
router(config)# interface tunnel1
router(config-if)# service-policy output child
Class Based Weighted Fair Queueing not supported on this interfaceTunnel interfaces also support class-based policing, but they do not support committed access rate (CAR).
Note: Service Policies are not supported on tunnel interfaces on 7500.
also a cisco guru told me it is not advised to configure cbwfq on tunnel interfaces when you have a lot of tunnels, 30 will kill the cpu, so you should put it on the physical interface
