Basic Definitions : Basic Definitions Network - A group of computers connected together in a way that allows information to be exchanged between the computers.
Node - Anything that is connected to the network. While a node is typically a computer, it can also be something like a printer or CD-ROM tower.
Segment - Any portion of a network that is separated, by a switch, bridge or router, from other parts of the network.
Backbone - The main cabling of a network that all of the segments connect to. Typically, the backbone is capable of carrying more information than the individual segments. For example, each segment may have a transfer rate of 10 Mbps (megabits per second: 1 million bits a second), while the backbone may operate at 100 Mbps.
Topology - The way that each node is physically connected to the network.
Types of Topology : Types of Topology BUS
RING
STAR
Bus Topology : Bus Topology Bus: each node is daisy-chained (connected one right after the other) along the same backbone. Information sent from a node travels along the backbone until it reaches its destination node. Each end of a bus network must be terminated with a resistor.
Ring Topology : Ring Topology Ring: Similar to a bus network, rings have nodes daisy chained, but the end of the network in a ring topology comes back around to the first node, creating a complete circuit. Each node takes a turn sending and receiving information through the use of a token. The token along with any data is sent from the first node to the second node which extracts the data addressed to it and adds any data it wishes to send. Then second node passes the token and data to the third node, etc. until it comes back around to the first node again. Only the node with the token is allowed to send data . All other nodes must wait for the token to come to them.
Star topology : Star topology In a star network, each node is connected to a central device called a hub. The hub takes a signal that comes from any node and passes it along to all the other nodes in the network.
A hub does not perform any type of filtering or routing of the data.
A hub is a junction that joins all the different nodes together.
Star : Star
Major Categories of Networks : Local Area Networks (LAN)
A network of computers that are in the same general physical location, within a building or a campus.
Metropolitan Area Networks (MAN)
Wide Area Networks (WAN) Major Categories of Networks
Data Communications Through WANs : Data Communications Through WANs WANs were developed to communicate over a large geographical area (e.g. lab-to-lab; city-to-city; east coast-to-west coast; North America-to-South America etc)
WANs require the crossing of public right of ways (under control and regulations of the interstate commerce and institute of telephone and data communications established by the gov’t and international treaties).
WANs around the world relies on the infrastructure established by the telephone companies (“common carrier”) or public switched telephone network (PSTN).
WANs consists of a number of interconnected switching nodes (today = computers). Transmission signals are routed across the network automatically by software control to the specified destination. The purpose of these nodes are to route messages through switching facilities to move data from node to node to its destination.
Metropolitan Area Networks : Metropolitan Area Networks Also known as a MAN, a metropolitan area network is basically a bigger version of a LAN and normally uses similar technology. It might cover a group of nearby corporate offices or a city and might be either private or public. A MAN can support both data and voice, and might even be related to the local cable television network. A MAN just has one or two cables and does not contain switching elements, which shunt packets over one of several potential output lines. Not having to switch simplifies the design.
Number System : Number System Binary System- A number system which uses two symbols or digits 0 and 1 to represent any number is called a binary system.
Octal system- A number system which uses 8 digits “ 0,1, 2, 3, 4, 5, 6, 7” is called octal system
Slide 11 : Decimal System- A number system which uses 10 digits “ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,” is called decimal system.
Hexa- Decimal System- A number system which uses 16 symbols “0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F” IS CALLED Hexa decimal system. In this system A is used to represent 10, B is used to represent 11, C is used to represent 12, D is used to represent 13, E is used to represent 14, F is used to represent 15,