You may have noticed that each device’s address is followed by /24.Thus, in this example, the range of possible host addresses is. 255 address is reserved for broadcast transmission, when devices need to communicate simultaneously with every host in their network, and cannot be assigned to an individual host. The range of possible host addresses is limited by the number of binary bits within the host octet, so in theory the range is. Note that all the PCs in the figure above share the same network address, but have unique host addresses.To make the addresses even easier to work with, they are divided into four 8-bit blocks called octets: Because IP addresses are designed to be used by computing devices, they are actually 32-bit binary numbers, which are converted to decimal to make them easier for people to work with.Therefore, we can say that an IPv4 address contains a network and a host component.The identity of the device, or host, within the network for which the packet is intended is ‘.10’.The address identifies the network that the packet has to be delivered to using the ‘192.168.10’ portion of the address.This is very important, as the house probably contains a number of people and they need to be able to determine who the letters is for. It also identifies the person in the house for whom the letter is intended. The address identifies the house, street and town that the postal service needs to use to deliver the letter.Similarly, networking has many layers of wrapping, or encapsulation, which are each used to help in the reliable transmission of data. Continuing the birthday present analogy, many of you may have sometime in the past played pass the parcel – a children’s game involving a present that has many layers of wrapping.So, encapsulation is the thin, additional layer of information used to wrap around data when it is sent between computers. Think of presents you may be given for your birthday – they are encapsulated in wrapping paper. Encapsulation is a complex term used to describe a simple technical process.The process of adding the IP header to the data is called ‘encapsulation’. The information added to the data to create the packet is called the IP header.IP includes other information within the packets, including its size, and some information about the type of data that the packet contains (e.g.When you send a letter, you normally write the address of the recipient (destination) on the front and your own address (source) on the back. This is very similar to the way that you address a letter that you send through the post.IP is responsible for delivering the packets from source to destination, and regardless of the version being used, packets must use some form of addressing to uniquely identify the message source and message destination.There are two versions of IP: version 4 and version 6. These are placed into containers called packets, typically by the Internet Protocol (IP). When a ‘message’ such as a file, image or video is transmitted across a network, it is first broken down into small blocks called segments.The media chosen will determine the type of transmitter and receiver required.Examples of unguided media include wireless technology such as:.Examples of guided media include wired technology such as:.

The transmission media can be either guided or unguided.Traditionally, the sources and destinations within information networks were computers, but today there are a wide range of devices capable of exchanging data:.The term ‘network’ in this course refers to data or information networks capable of carrying many different types of communications, including traditional computer data, and interactive voice, video and entertainment products.A receiver is used by the message destination to recover data from the transmission media. A transmitter is used by the message source to place data onto a transmission media. In computer networks, the media is usually a type of cable, or a wireless transmission. The bits are then encoded into a signal that can be transmitted over the appropriate medium. These can be sent across a data or information network by first converting them into binary digits, or bits. Consider, for example, communicating a message using words, pictures and sounds.

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