CCNA Collaboration Question of the Week: Deploying VoIP

Answer: A, B and C.

Per Cisco, when deploying VoIP, there needs to be ample bandwidth to support the voice calls. Also, the support for QoS markings to prioritize the voice data and signaling. Typically the voice data is marked with a Class of Service (COS) of 5 at layer; IP Precedence of 5 or DSCP value of 46 or EF (Expedited Forwarding) at layer 3. The signaling is typically marked as COS of 3; IP Precedence of 3 or DSCP of 24 or CS3 (Class Selector). The final critical piece is the latency or the delay from end to end.  Cisco recommends no more than 150 milliseconds for a one way or 300 milliseconds round trip delay for toll quality voice.