Lab: VoIP Traffic Engineering

Objectives

In this lab, students will examine the following objectives.

•Calculate the VoIP traffic load in access trunks to the packet network.
•Calculate the number of IP PBX access channels to the packet network.
•Calculate the number of backup access channels to PSTN.

Scenario

ABC Inc. is planning to retire an analog PBX serving its location, and to deploy an IP PBX to integrate telephone services into the TCP/IP network using VoIP technologies. It plans to use primarily the packet network (Internet) to make and receive phone calls. To meet its phone service objectives, ABC Inc. must size access links to the Internet and determine the number of SIP trunk connections that are needed. In addition, the company wants to have a backup connection (i.e., a subscription to a few analog lines) to the PSTN through a trunk gateway in case of failure in the packet network.

Your task is to calculate the following traffic engineering parameters to correctly size access connections to WAN.

1) Calculate VoIP traffic load in access trunks to the Internet.

2) Calculate the access bandwidth required and the number of SIP trunks needed for VoIP calls to the Internet.

3) Calculate the number of backup access channels to PSTN.