Networking
Networking Links
| An Educators Guide to
School Networks http://fcit.coedu.usf.edu/network/ This site describes networks - LAN, MAN & WAN. Advantages and Disadvantages of installing a School Network. Important terms are defined. |
| A Guide
to Networking a K-12 School District Table of Contents http://devius.cs.uiuc.edu/schools/bl-thesis/toc.doc.html This site introduces the reader to layout and design of a network. Tips on getting connected to other parts of the world. View resources and see where to look for help. |
| Consortium
for School Networking (CoSN) http://www.cosn.org The Consortium for School Networking (CoSN), a national nonprofit organization, promotes the use of information technologies and the Internet in K-12 education to improve learning. Our members represent school districts, state and local education agencies, ,nonprofit companies and individuals who share our vision. |
A Guide to Networking for K-12 Schools http://www.netc.org/network_guide/ This site is a starting point for learning about networks; includes common components and practices in the design and construction of today's networks. Describes some of the benefits that can be derived from school networks and more. |
| School Networking Resources http://www.netc.org/network_guide/f.htm Northwest Educational Technology Consortium The Northwest Educational Technology Consortium (NETC) is operated out of the Northwest Regional Educational Laboratory (NWREL) and is one of six federally funded Regional Technology in Education Consortia (R*TEC). The national program was established in the fall of 1995 to help states, local educational agencies, teachers, school library and media personnel, administrators, and other education entities successfully integrate technologies in K-12 classrooms, library media centers, and other educational settings, including adult literacy centers and teacher education programs. The members of the Northwest consortium include the six state education agencies of Alaska, Idaho, Montana, Oregon, Washington, and Wyoming, the Educational Service District 101 (based in Spokane, Washington), and NWREL as the lead grantee. The activities of the consortium in each member state are tailored to the needs of each state and are coordinated to complement existing delivery mechanisms or programs.Network Montana contact: |
Resources To Be Used When Creating a School Network
Resources
Important Networking Terms
| Peer-to-peer networks
and client/server networks- In peer-to-peer networks
each client has its own storage area, which might be shared with
other clients. There is no central storage in this type of network.
Peer-to-peer networks are often used in small classroom computer
labs. Client/serverfile server used in reference
to these storage devices. A client may use the network to connect
to one of these storage devices to get documents to vi networks
have storage devices on the network that may hold data for users
to share. If you have worked on a client/server network, you have
probably heard the term ew or edit. |
| LAN and WAN-A local area network, or LAN,
is a network in which all clients share a common infrastructure (wires)
and are usually in the same building, or group of buildings.
In contrast, a wide area network, or WAN, is one that spans a larger geographic area. For instance, a network that links two or more LANs that are separated by some distance might be called a WAN. |
| Topology-The
topology defines the shape of a network. Some networks are shaped like
rings with all the client stations connected in a logical circle;
others are shaped like stars with all the client stations connected
to a central point. Probably the most common network topology today
is the star as exemplified by 10BaseT networking. |
| Networks are patterned in three general topologies:
the star, the ring, and the bus.
Star topology. The star topology for a local area network looks like a star. All network wiring runs from the client to a central location or hub. 
Ring topology. The ring or loop topology connects computers in a continuous loop. In local area ring networks, though, the physical wiring topology really looks like a star. The logical ring topology depends on the network electronics you are using. IBM's Token Ring takes advantage of this topology. The token is constantly passing around the network. A computer can transmit when it gets the token. 
Bus topology. The bus topology was the first local area network topology in use. In this pattern network clients are strung along a single cable. The cable must be electrically terminated at each end to function properly. A variation of the bus topology is the daisy chain. In a daisy chain, the first component is connected to the second, the second to the third, the third to the fourth, and so on. 
Each of the topologies creates different needs for support and troubleshooting. Most local area networks today use the star topology because it tends to be the easiest to troubleshoot. Pictures and related information downloaded formhttp://www.netc.org/network_guide/5.html |
Protocol A protocol is a standard for how things are to be done. With
computers and networking a protocol is how devices communicate. Protocols
can be broken down into layers. There are physical protocols
which specify things like voltage levels on wires. Network
protocols specify how a client might request a re-transmit
of some data that it needs. 
OSI seven-layer model compared
to various interconnect device functions and to several media access
protocols 
Reprinted with permission of Fluke Corporation. Network Maintenance & Troubleshooting Guide, copyright 1997. Guide available from Fluke (1-800-90FLUKE, part number 200730) See complete page @ http://www.netc.org/network_guide/c.html
Ethernet. Ethernet
is an industry standard protocol operating at 10 Mbps that is currently
in wide use. The protocol uses a principle called Carrier Sense Multiple
Access/Collision Detection (CSMA/CD) which has two important parts
to it. The first is that it is a multiple access protocol allowing all
the machines to share the same physical wiring instead of requiring separate
wiring for each machine (except in the case of a star topology). The
second is that it operates on collision detection. Since many machines
share the wire, two machines may try to use it at the same time. If this
occurs, a collision has occurred. The network hardware detects the collision
and aborts the network access. After a small random delay, the hardware
tries to transmit again. The result of this protocol is that on very busy
networks with many machines, a large number of collisions can occur, wasting
a significant amount of time retransmitting information. This is why
there is a recommended limit of 25 to 30 machines on a single Ethernet
network. |
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A few technologies for networking
the WAN
Types of internetwork communication connection options. Private fiber, coax, or copper lines. Require know-how, equipment, and installation, but you have no monthly fees. Private radio, microwave, or satellite-based wireless connections. Require know-how, equipment, and installation, but no monthly fees. The technology is emerging and costs are coming down. Channel space on an existing cable-TV system. Works in some places where cable systems are set up with excess capacity, requires cable company cooperation, and will likely incur regular fees. Requires special modems that need to be matched to cable company specifications. Telephone company data lines. This is by far the most common option. It is available most places, and requires equipment, installation, and monthly fees. Many standards are available, and technology is mature, stable, and well understood. See more @http://www.netc.org/network_guide/5.html |
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Network Equipment: Repeaters are the most basic type of active network equipment.They operate solely at the physical layer, receiving a signal on one port, or connection, and rebroadcasting it on all of its other ports. They can extend a network beyond the limits imposed by the wiring by boosting the signal level. Most advertisements for "hubs" are referring to multiport repeaters. They usually come with a number of ports that are multiples of 12 and allow the network to support up to that number of workstations. Some hubs are stackable, which means they have a special connector that allows a district to easily connect more than one hub together. Others come as chassis systems for which support additional cards, each card having another 12 ports. Switches are an advanced form of repeaters. They also act at the physical level by repeating the signal. Unlike repeaters that repeat an incoming packet out all of its ports, a switch looks at the destination of the packet and only sends it to the port of the destination. This can reduce excess traffic on a network since it isolates each port and send fewer packets to each port, thereby reducing collisions and increasing the performance of the network. Bridges operate at a higher level than repeaters, working at the data link layer and looking at the actual packets that are on the network. When they receive a packet, they store the entire packet in memory, verify its correctness, and retransmit it on the correct port. This allows them to connect different types of Ethernet networks together such as a 10baseT and a coax network. They also reset the "3-4-5 rule" for each port, making each port its own network. This is because it stores the entire packet and rebroadcasts it, isolating each port from the others. Like switches, they look at the destination of the packet and only send it to the port where the destination is located, reducing traffic on the network. Routers operate at the network level. They receive a packet, view its destination, and determine if the packet is destined for a network that is directly connected to the router or if it is destined for a network further away. If it is the first it sends the packet to the correct port. If it is the latter, it sends the packet to the next router along the path to the packet's final destination. For this reason, routers typically connect between a LAN and a WAN to limit the traffic on the WAN to only packets that need to cross it. Additionally, because routers look at the network information from a packet, they can convert between different network protocols. http://devius.cs.uiuc.edu/schools/bl-thesis/Implementation.html#3395 The network interface card (NIC) is an add-on board that serves as the connection between the client computer and the network infrastructure. In other words, to hook all your computers together, a special electronic circuit card called a NIC goes inside each computer. That's where you plug in the cable that connects the computer to the network. Some computers come with built-in network interfaces and do not require an additional NIC. You will find that NICs vary in cost depending on the type of protocol they support. For example, 10BaseT NICs are inexpensive when compared to FDDI NICs. http://www.netc.org/network_guide/5.html Unshielded twisted pair (UTP) wire. Unshielded twisted pair has been used by telephone companies for years to attach phones for local service. Today it is used in data-network applications. Because of the use of UTP in data communications, seven specifications have emerged and it has become the most common media type for LANs today. 
Fiber optic cable. Fiber optic cable uses light instead of electricity to carry data. Data can be moved at extremely high speeds without generating radio frequency signals and data transmission is not affected by the proximity of electrical equipment. Most fibers are made of glass, plastic, or plastic-clad glass. There are three components to optical fiber: the core, the cladding, and the coating. The cladding blocks exterior light sources and restricts the internal light to the core only. The coating is usually plastic and its purpose is to protect the fiber from being damaged. 
There are two categories of fiber: single mode and multimode. Single-mode fiber has a smaller diameter core, generally uses laser as a light source, and can transmit data in excess of 25 miles and can transmit data up to a mile. LANs and campus networks usually make use of multimode fiber. Both categories of fiber are generally much more expensive than twisted pair wire. Because of this, fiber is usually limited to situations where long distance runs or very high speeds are needed. Coaxial cable. Coaxial cable is probably the most well-known type of cable. This class of cable has several layers of material surrounding a common axis. A center conductor, either solid or stranded, is surrounded by a nonconductive material, covered by a shielding material, then covered by an abrasion-resistant jacket. At one time, coaxial cable was the only media available for use in data networking. Today, the most common use of coaxial cable is for video distribution, while UTP and fiber are commonly used in data networking. 
Wireless media. Several new technologies allow for the use of radio or microwave transmission for data networks. Wireless systems have special applications in interbuilding communication and might be useful in your campus or district networks. Be aware that there are trade-offs with wireless. Reliability, cost, and performance should be carefully analyzed. UTP is the most widely used and therefore is the most cost effective to maintain. It also has multiple uses and applications and is the one I would use in a school network.Wazza's School Computer Network Info http://members.ozemail.com.au/~wazmac/ Networking and intranet explanations and suggestions for schools. All new networks installed in schools are Ethernet networks. Wierless Networks are not actually
a cable, but rather an alternate means of connecting one site
to another using "radio transmission". This is still fairly
pricey, but an option for sites which are difficult to cable,
due to their construction or their layout. Networking Design and Reserch
Center
http://www.alaska.net/~research/index.htm The Networking Design and Research Center This site has a lot of information, find networking terms listed alphabetically, links to tutorials, downloads, white papers and links to other network resources. Network engineer consulting services are also available! |
