This video covers how to police voice, signaling and video traffic from phones on the Catalyst 3750 . It is one of a series of videos taken from the CollabCert LMS self-study product.
Vik Malhi, CCIE#13890
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Twitter: @vikmalhi
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In this example we want to apply a policer to each individual phone at a branch office so that each phone can only produce enough bandwidth for 1 g711/g722 audio call. Non-conforming voice traffic (RTP packets above the 93Kbps used for that single g711/g722 audio call) will be dropped. The idea here is there must be something sinister going on if a phone is producing more than 1 calls worth of traffic and we want to protect our network by dropping this sinister traffic at the source. The other requirements are that video traffic from each individual phone is policed to 1Mbps and signaling is policed to 24kbps. In both of these cases we won’t drop the non-conforming traffic but instead mark down the layer 3 DSCP Per Hop Behavior to a lower priority (CS1 or DSCP 8).
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:
Continue reading Per Call bandwidth Consumption over Ethernet+802.1Q
