FIT1047 Tutorial 8 – Sample Solution

FIT1047 Tutorial 8 – Sample Solution Topics and goals • Network layers and protocols, learn about addresses at various layers • Application layer – HTTP • Familiarise yourself with some of the networking tools Instructions The tasks are supposed to be done in groups of two or three students. Task 1: Basic knowledge Briefly explain the following terms: 1. Bit rate, bandwidth Bit rate: the numbers of bits that can be transmitted over a data communications channel per time unit, usually measured in bits per second (or kilobits, megabits, gigabits per second). Bandwidth: strictly speaking, the width of a range of fre-quencies (i.e. highest minus lowest frequency). E.g. each channel in WiFi has a bandwidth of 20 MHz. But it’s often used as a synonym for bit rate. 2. Latency The time it takes for a message from being sent to being received. Note that a network can have a very high bit rate but still feel slow: e.g. consider using a satellite connection for a video conference: you can stream very high quality video over the satellite connection, but due to the high latency, you could experience a delay of several seconds, which makes the connection almost unusable for real-time communication. This is also often a problem when playing real-time online video games. 3. Networks layers, PDU, encapsulation 1 The network layer is the third level of the five layer architecture (TCP/IP Model) and the layer that provides data routing paths for network communication. Data is transferred in the form of packets via logical network paths in an ordered format controlled by the network layer. PDU: Short for Protocol Data Unit. The term used to describe data as it moves from one layer of the TCP/IP model to another. In this reference, PDU is often used synonymously with packet. Encapsulation is the process of taking data from one layer protocol and translating it into another layer protocol, so the data can continue across a network. For example, a TCP/IP packet contained within an ATM frame is a form of encapsulation.