CBWFQ with GRE Tunnel

Unanswered Question
Feb 23rd, 2007

hi all,

recently my company has developed network with GRE Tunnel. But when I try to add qos feature using class based weighted fair queue, the router refuse and tell that CBWFQ is not supported in interface tunnel. is there a way for interface tunnel for using qos feature

Thx in advance

I have this problem too.
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eclaereboudt Tue, 02/27/2007 - 05:35


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

ryan.setiawan Sun, 03/04/2007 - 19:39

hi all,

Thx for the solution I very appreciate it.

eclaereboudt, you told me to configure cbwfq in the physical interface, I have already did that, but it didn't make an effect, because when I tried in serial interface the packet have already encapsulated with GRE header, so the serial can't see the ToS field or DSCP. But you're right having a lot of tunell running cbwfq will kill the cpu, so there must be a way running service-policy in physical interface



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