Network that is confined to a small area: writing lab, school or building.

Computers that are connected to a network are broadly categorized as servers or workstations.

Servers generally aren't used by humans directly, run continuously to provide "services" to the other computers on the network.

workstations have human users which interacts with the network through them. Workstations-desktop, consisting of a computer, keyboard, display, and mouse or a laptop.

Servers more powerful than workstations, configurations are guided by need.

Networks in larger geographic areas- such as United States or the world. Transoceanic cabling or satellite uplinks may be used to connect this type of global network.

Disadvantages: expensive to install, requires administrative time, servers fail, cables may break, and security and compliance.

OSI- Open Systems Interconnection defines seven layers of networking protocols.

OSI Layers: Application, Presentation, Session, Transport, Network, Data Link, Physical

Ethernet developed in 1983, had a maximum speed of 10 Mbps over coaxial cable. This cable was heavy, expensive to purchase, install, and maintain and difficult to retrofit into existing facilities.

Fast Ethernet supports transmissions up to 100 Mbsp. requires the use of different more expensive network concentrators/hubs and network interface cards.

Gigabit Ethernet has a transmission speed of 1 Gbps. Can be used with both fiber optic cabling and copper.

Every network device have a physical address called a MAC- (Media Access Control) address. Networks using the IP and IPX protocols assign logical addresses to the devices on the network.

Laptops/Mobile- these are becoming more and more common. Have decent internal storage, but also enough power to serve as a workstation on the go. Usually always have a wireless adapter to allow quick network connections.

Ethernet Cards- usually included with a computer, although additional cards can be purchased and installed on most computers.

ethernet switch is a device that provides central connection points for cables from workstations, servers, and peripherals.

Bridges are devices that allows you to segment a large network into two smaller more efficient networks. It monitors the information traffic on both sides of the network so that it can pass packets of information to the correct location.

2) Shielded Twisted Pair (STP) cable

3) Coaxial Cable

4) Fiber Optic Cable

5) Cable Installation Guides

6) Wireless LANs

7) Unshielded Twisted Pair (UTP) cable

Shielded is the least expensive, may be susceptible to radio and electrical frequency interference.

Great for allowing laptop computers, portable devices, or remote computers to connect to the LAN. Wireless networks are beneficial in older buildings where it may be difficult or impossible to install cables.

Two most common types of infrared communications used in schools are line-of-sight and scattered broadcast.

Line-of-sight must be an unblocked direct line between the workstation and the transceiver.

Scattered broadcast of infrared transmissions sent out in multiple directions that bounces off walls and ceilings until it eventually hits the receiver.

Encryption- use the strongest encryption supported by the devices. Strong passwords.

Isolation- use wireless router that places all wireless connections on a subnet independent of the primary private network.

Hidden SSID- Disable this feature

Main Types of Physical Topologies:

1) Linear Bus

2) Star

3) Tree

4) Considerations When Choosing a Topology

5) Summary Chart

Advantages of a linear bus topology:

1)easy to connect a computer or peripheral to a linear bus

2)requires less cable length than a star topology

Disadvantages of a linear bus topology:

1)entire network shuts down if there is a break-in the main cable.

2)Terminators are required at both ends of the backbone cable.

3)Difficult to identify the problem if the entire network shuts down.

4)Not meant to be used as a stand alone solution in a large building.

Data on a star network passes through the hub, switch, or concentrator before continuing to its destination.

Advantages:

1)easy to install and wire

2)no disruptions to the network when connecting or removing devices

3)easy to detect faults and to remove parts

Disadvantages:

1)requires more cable length than a linear topology

2)if the hub, switch, or concentrator fails, nodes attached are disabled

3)more expensive than linear bus topologies because of the cost of the hubs, etc.

Advantages-

1) point-to-point wiring for individual segments

2) supported by several hardware and software venders

Disadvantages-

1) overall length of each segment is limited by the type of cabling used

2) if the backbone lien breaks, the entire segment goes down

3) more difficult to configure and wire than other topologies

Length of Cable Needed- the linear bus network uses shorter lengths of cable.

Future Growth- with a star topology, expanding a network is easily done by adding another concentrator.

Cable Type- The most common cable in schools is unshielded twisted pair, which is most often used with star topologies.

Two major types of network operating systems

1) Peer-to-Peer

2) Client/Server

Nearly all modern networks are a combination of both.

Advantages-

1) less initial expense- no need for a dedicated server

2) setup- an operating system already in place may only need to be reconfigured for peer-to-peer operations.

Disadvantages-

1) Decentralized- no central repository for files and applications

2) Security- does not provide the security available on a client/server network.

Advantages-

1) Centralized-resources and data security controlled through server.

2) Scalability- any or all elements can be replaced individually as needs increase.

3) Flexibility- New technology can be easily integrated into system.

4) Interoperability- all components work together.

5) Accessibility- server can be accessed remotely and across multiple platforms.

Disadvantages-

1) Expense- requires initial investment in dedicated server.

2) Maintenance- large networks will require a staff to ensure efficient operation.

3) Dependence- when server goes down, operations will cease across network.