I am connecting to a 100Mbit WAN circuit, that is Burstable to 500Mbit. If I am going to use ASA traffic shaping on this, would I set the shape average to 100Mbit or 500Mbit? My main concern is protecting VOIP, while allowing file transfers access to the burst.

Here is what I have so far.

This is to match the Voice Traffic

class-map voice_traffic
match dscp EF AF31

This is to priorities the voice

policy-map qos_class_policy
class voice_traffic

And here is the shaping policy that will be applied to the outside interface.

policy-map qos_outside_policy
class class-default
shape average 100000000
service-policy qos_class_policy

And here it is applied to the external interface 'outside'

service-policy qos_outside_policy interface outside

Here are the options on the ASA to set the shape, and then set the burst commit.

mpf-policy-map-class mode commands/options:
  <64000-154400000>  Target Bit Rate (bits per second), the value needs to be
                     multiple of 8000
ASA(config-pmap-c)# shape average 10000000 ?

mpf-policy-map-class mode commands/options:
  <2048-154400000>  bits per interval, sustained. Needs to be multiple of 128. 
                    Recommend not to configure it, the algorithm will find out
                    the best value
  • the policy called qos_outside_policy above will shape all traffic (including voice and file transfers) to 100M Jul 13, 2013 at 2:44

1 Answer 1


What you want to have is the VoIP traffic is always inside the 'first' 100M, and data can go outside it. So that when far-end policer/shaper needs to drop, they'll just drop the traffic after the 'first' 100M. This is not possible at all.

Once the provider policer/shaper starts dropping due to you exceeding 100M for long time, if they don't share your view of QoS policy, they'll drop indiscriminately your voice and data.

So config you have right now, is best you can do.

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