The question of how much bandwidth does a call consume  is something that has occupied the minds of many “collaboration” engineers over the years and specifically is something that you should be aware of if you plan on sitting the CCIE Collaboration lab exam. I’m going to tell you how to do it without referencing any resources.

To set the scene, I want to police Voice/RTP traffic from a phone in my Headquarters office. We shall call this HQ Phone 2.

The policer will be applied on the switchport of HQ Phone 2 (ingress). I am using a 3560X switch.

The details of the policer are as follows: we will assume that conforming packets are all RTP packets for 1 g722 call. Any traffic above and beyond what is needed by 1 call is going to be non-conforming and is subject to an “exceed” action within the policer. The conforming action of the policer is to set the DSCP to the PHB of Expedited Forwarding (EF) and transmit. The exceed action of the policer is to drop packets.

Let’s look at our configuration:

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