Networks

What a network is

A network is 2 or more devices connected together to share data, resources or communication.

1. Why we network - 3 reasons

a. Communication
Administrators, instructors, and even students and guests can be connected using the campus network.

b. Share Resources
The school can provide access to special purpose computing devices which individual users would not normally own. For example, a school network might have high-speed high quality printers strategically located around a campus for instructor or student use.

c. Share Data
Computers allow users to create and manipulate information. Information takes on a life of its own on a network. The network provides both a place to store the information and mechanisms to share that information with other network users.

1. Topology - 6 different types - pros & cons
a. Peer to Peer
Two devices connected directly together.
b. Linear Bus
A linear bus topology consists of a main run of cable with a terminator at each end (See fig. 1). All nodes (file server, workstations, and peripherals) are connected to the linear cable.
c. Star
A star topology is designed with each node (file server, workstations, and peripherals) connected directly to a central network hub, switch, or concentrator (See fig. 2).
Data on a star network passes through the hub, switch, or concentrator before continuing to its destination. The hub, switch, or concentrator manages and controls all functions of the network. It also acts as a repeater for the data flow. This configuration is common with twisted pair cable; however, it can also be used with coaxial cable or fiber optic cable.
d. Tree
a tree topology combines characteristics of linear bus and star topologies. It consists of groups of star-configured workstations connected to a linear bus backbone cable (See fig. 3). Tree topologies allow for the expansion of an existing network, and enable schools to configure a network to meet their needs.
e. Token Ring
Token ring local area network (LAN) technology is a protocol which resides at the data link layer (DLL) of the OSI model. It uses a special three-byte frame called a token that travels around the ring.
f. Wireless
Wireless networking is a method by which homes, telecommunications networks and enterprise (business) installations avoid the costly process of introducing cables into a building, or as a connection between various equipment locations.


2. Devices
a. PC
The letters 'PC' stand for 'personal computer' – that is, a computer that can fit on a single desk for use by ordinary people, as opposed to a huge mainframe or supercomputer.
b. Server
A computer or computer program which manages access to a centralized resource or service in a network.
c. Printer
In computers, a printer is a device that accepts text and graphic output from a computer and transfers the information to paper, usually to standard size sheets of paper.
d. Hub
A common connection point for devices in a network. Hubs are commonly used to connect segments of a LAN. A hub contains multiple ports. When a packet arrives at one port, it is copied to the other ports so that all segments of the LAN can see all packets.
e. Switch
A network switch (also called switching hub, bridging hub, officially MAC bridge) is a computer networking device that connects devices together on a computer network, by using packet switching to receive, process and forward data to the destination device.
f. Router
A router is a networking device that forwards data packets between computer networks. Routers perform the "traffic directing" functions on the Internet. A data packet is typically forwarded from one router to another through the networks that constitute the internetwork until it reaches its destination node.
g. Patch panel
A patch panel serves as a sort of static switchboard, using cables to interconnect computers within the area of a local area network (LAN) and to the outside for connection to the Internet or other wide area network (WAN).


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1. Bandwidth - amount of data, equates hose pipe
Bandwidth refers to the amount of information that can be transmitted over a network in a given amount of time, usually expressed in bits per second or bps. It is often confused with speed. Speed is the time it takes for one piece of information to get from point A to point B. Think of two moving carpets or "bands" of different widths, both moving at identical speeds. Two boxes, one placed on each moving carpet will both reach the end at the same time, but the wider carpet can carry more boxes than the narrow one. Thus, a network with more bandwidth can carry more information per second than one with less bandwidth.
2. Wireless vs Hardwired comparison
Typical 802.11g Wireless has a theoretical maximum of 54Mbps. Typical wired 10/100 Ethernet has a theoretical maximum of 100 Mbps. So in theory wired is faster.
However, these speeds are only on your local network. Most high-speed internet connections range from 1Mbps to 25 Mbps. Even on faster internet connections you're only approaching 1/2 of the full throughput of your wireless system. In practice, it’s not likely you will see much of a difference unless you are transferring very large amounts of data across your local network. I typically make the wired/wireless decision based on the usage of the machine. If it is a desktop that will never move, wired is the way to go. If it’s a laptop that will be mobile, the convenience of wireless by far outweighs any difference in transmission speed.
3. Peer to Peer vs Client Server comparison
A peer-to-peer network has no central server. Each workstation on the network shares its files equally with the others. There’s no central storage or authentication of users. Conversely, there are separate dedicated servers and clients in a client/server network. Through client workstations, users can access most files, which are generally stored on the server. The server will determine which users can access the files on the network.
Peer-to-peer networks should be installed in homes or in very small businesses where employees interact regularly. They are inexpensive to set up (comparatively speaking); however, they offer almost no security. On the other hand, client/server networks can become as big as you need them to be. Some support millions of users and offer elaborate security measures. As you can imagine, client/server networks can become very expensive.



Downloads

1. Network devices - Click Here
2. Network Terms - Click Here
3. Communication Methods - Click Here

School Topology
School Topology - Click Diagram for Larger Picture