ENVS 1000 Lecture Notes - Lecture 1: User Friendly, Packet Switching, Wide Area Network
10 May 2018
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ENVS 1000 Tutorial 1 Notes – Transmission
Introduction
• Messages are broken into packets for transmission through the network.
• The prevalent transmission media are fiber optic cable, copper wire, and radio.
• Packets are routed using either packet switching or virtual circuit switching.
• With packet switching, each packet is routed individually.
• With virtual circuit switching, all packets in a message follow the same path through the
network.
• Management of packets is performed by protocol suite software.
• The most common suite is TCP/IP.
• TCP/IP tasks are divided into five layers: application, transport, network, data link, and
physical.
• Most messages are created at the source application layer, are converted to packets,
and pass through the other layers, adding header information at each layer along the
way.
• At the destination, the process is reversed; each layer strips off its header, until the
message is finally delivered to the corresponding application.
• There are four types of addresses used in networking.
• Port numbers identify the application.
• IP, or logical, addresses are used for the source and destination.
• Physical addresses identify each hardware component.
• User-friendly addresses, such as domain names, make it easier for users to interact with
the network.
• Topology describes the physical and logical layout of a network.
• The common topologies include bus, start, mesh, and ring.
• Networks are loosely categorized by range as local area networks, backbone networks,
metropolitan area networks, and wide area networks.
• The Internet is a large wide area network.
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