Netw 320 Lab 5 Insturctions

NETW320 -- Converged Networks with Lab

Lab #5 Title: Codec Selection for Campus Network

Introduction

A codec is a device capable of performing encoding and decoding on a digital signal. Each codec provides a different level of speech quality. The reason for this is that codecs use different types of compression techniques in order to require less bandwidth. The more the compression, the less bandwidth you will require. However, this will ultimately be at the cost of signal quality, as high compression/low bandwidth algorithms will not have the same voice quality as low compression/high bandwidth algorithms.

The following table shows three standard codec types along with their corresponding Coder Type, Bit Rate, Frame Size Delay, and Look Ahead Delay. These particular three were chosen because these are the ones we will use in this lab, but there are others.

ITU Recommended Delay Values/G.114

Compression Method | Coder Type | Bit Rate | Frame Size Delay (milliseconds) | Look Ahead Delay (milliseconds) |

G.711 | PCM | 64 kbps | 0.125 | 0 |

G.729 | CS-ACELP | 8 kbps | 10 | 5 |

G.723.1 | ACELP | 5.3 kbps | 30 | 7.5 |

A common scale used to determine the quality of sound produced by various codecs is the Mean Opinion Score (MOS). This standard is based on a scale from 1 to 5 where 1 is very poor and 5 is excellent. Here is a common table used to rate values of MOS.

MOS | Listening Quality | Listening Effort |

5 | Excellent | Complete Relaxation |

4 | Good | Attention Necessary |

3 | Fair | Moderate Effort |

2 | Poor | Considerable Effort |

1 | Bad | No Meaning Understood |

Objectives

In this lab, you will build a campus network that will consist of several LANS. Then, you will configure two types of traffic to traverse the network: data and voice. You will then configure three scenarios to compare and analyze. For all three scenarios, the data and voice traffic generated will be held constant. The...