Networking Links:
An Educator's Guide to School Networks
This awesome site is compiled of six networking chapters that are each specifically divided into subjects, with their own links! The site also contains a reference and a glossary section to assist you in further research. In addition to the previous information, you will find an entertaining network game set up in Jeopardy format.
Consortium for School Networking
CoSN's main purpose is to serve as the premier national voice for promoting the use of the Internet and telecommunications to improve K-12 learning. This site is geared toward key technology leaders at the school district, state and national level. It is a great site for engaging in leadership development and also for creating great learning environments for students as well as teachers. They keep up to date on all of the latest technology trends and provide the needed framework for leaders to ask important technology related questions and evaluate their options.
A Guide to Networking K-12 Schools
Venturing to this site will provide basic networking information and planning assistance for technology coordinators and others involved in building networks for K-12 schools. This document assists you with designing a school network that meets teaching, learning, and administrative needs. The information focuses on the first few steps in the networking process. It also includes appendices of a planning worksheet; sample wiring specifications; information on the OSI 7-Layer Model; snapshots of school networks; and networking resources for Northwest schools. A bibliography and a glossary are also included to assist you in finding additional resources and mastering networking terminology.
School Networking Resources - Northwest Education Technology Consortium
Peer-to-Peer Networks: when using this type of network each client has its own storage area, which might be shared with other clients; no central storage in this type of network; often used in small classroom computer labs
Client/Server Networks: these networks have storage devices on the network that may hold data for users to share; a client may use the network to connect to a file server, the storage device, and get some documents to view or edit.
LAN- local area network: a network in which all clients share a common infrastructure (wires) and are usually in the same building, or group of buildings.
A comparison of the different LAN technologies.
Protocol Wiring Maximum bandwidth Maximum length
Topology Cost Ethernet Cat 5 twisted pair 10 Mbps 100 meters Star Low Thick 10 Mbps 500 meters Bus High Coaxial cable 10 Mbps 200 meters Bus Low Fiber 10 Mbps 1000 meters Star Very high Fast Ethernet Cat 5 twisted pair 100 Mbps 100 meters Star High Token Ring Coaxial cable 16 Mbps 100 meters Ring High FDDI Fiber 100 Mbps 1000 meters Star Very high CDDI Cat 5 twisted pair 100 Mbps 100 meters Star Very high Local Talk Cat 3 twisted pair 230 Kbps 300 meters Bus Very low ATM Fiber 1 Gbps 100 meters Star Very high
WAN- wide area network: spans a larger geographic area; example: a network that links two or more LANs that are separated by some distance might be called a WAN.
A Few Technologies for Networking the WAN:
Plain Old Telephone Service (POTS): This technology relies on standard phone lines to connect schools. Using current analog modem technology, this service can run at speeds up to 28.8 Kbps in each direction. It is a cheap and usually easy way to get a machine connected to the Internet quickly. It has low start-up costs and low monthly rates. If an extra phone line is already available, the school can reuse it with no installation charge. An ISP will need to provide Internet connectivity, but these are usually available at reasonable rates as well.Leased Line: Another type of WAN connection is a leased line. With a leased line, the district buys a permanent connection from the phone company, either to another school or to an ISP. The district sets up a router and a Channel Service Unit/Digital Service Unit (CSU/DSU) at each school that will connect and connects the leased line to the CSU/DSU. This establishes a network between the two ends of the leased line.
Integrated Services Digital Network (ISDN): ISDN is a technology that is finally becoming available from most telephone companies. It offers connections at either 64 Kbps or 128 Kbps in each direction. It also expands by multiples of 64 Kbps. The basic service, called a Basic Rate Interface (BRI), contains two 64 Kbps data lines called B-Channels and a 16 Kbps control line called a D-Channel. The phone company meters ISDN lines like a standard phone line. They only bill a district for the actual usage time of the line. Most ISDN connections will close after a few minutes of inactivity, keeping the usage charge down to a minimum. In addition, unlike a normal POTS modem, an ISDN connection is usually "dial on demand." This means that if a need arises to use the connection, the ISDN equipment will automatically establish the connection within one or two seconds. This allows users to continue working normally as the line connection opens and closes automatically.
Wireless: A cheaper approach to networking is to use wireless communications to connect multiple buildings. Offering high speeds and minimal or no recurring costs, these technologies deserve a good look. When compared with the phone company solutions, the up front costs are high, but over time this cost can amortize to the point where it is cost effective. Wireless may require expensive towers to clear natural and man-made obstructions around a school
because all wireless communications require a clear line of sight between the transmitting and receiving equipment.
Networking Definitions:
Protocols: a standard for how devices communicate.
Fast Ethernet: an industry standard protocol operating at 10 Mbps; 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.
Topology: the shape of a network.
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. The logical ring topology depends on the network electronics you are using.Bus Topolgy: 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.
Network
Equipment
Repeater: the most basic type of active network equipment that receives a signal on one port, or connection, and rebroadcasts it on all of its other ports. They can extend a network beyond the limits imposed by the wiring by boosting the signal level.
Hub: a device that serves as the center of a star topology network come in two basic models: stackable and modular. Stackable hubs have a fixed number of ports available to connect network devices. There are 4-, 8-, 12-, 16-, and 24-port models. Modular hubs offer a great deal of flexibility. It is possible to have an Ethernet network, AppleTalk network, and token ring network running in the same hub.
Bridge: 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.
Router: 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.
NICs: 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.
Cables
Unshielded Twisted Pair: cable used by telephone companies for years and now used in data communications. Seven specifications have emerged, ranging from Category 1 for voice grade to Category 7 for ultra high speed data. It has become the most common media type for LANs today.I believe that the unshielded twisted pair cable would be the most appropriate choice in a school setting. It is one of the most common types of cable used and is fairly reasonable in cost. Twisted cable is also very reliable in performance, which is an important contributing factor.
Fiber Optic: uses light instead of electricity to carry data. This accounts for two of its advantages: (1) Data can be moved at extremely high speeds without generating interfering RF (radio frequency) signals and (2) Data transmission is not affected by the proximity of electrical equipment or high voltage transmission.
Coaxial: a class of cable that 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.
Wireless: use of radio or microwave transmission for data networks. Wireless systems have special applications in inter building communication, but be
aware that there are trade-offs with wireless, reliability, cost, and performance should be carefully analyzed.
Wazza's
School Computer Network Information
Wazza's School Computer Network Info.
Networking and intranet explanations and suggestions
for schools.
*All new school computers are Ethernet networks.
*The recommended school standard for cabling is the Unshielded
Twisted Pair or a UTP cable.
*Wireless school networking uses "radio transmissions" to
connect computers and transmit data. This is an option for
schools
that have a strange layout for wiring and need to have all classrooms
connected.
*A school intranet is an internal computer network
which uses
tools and protocols normally associated with the internet.
Students
using the intranet are able to feel as if they are using the
internet.
Students are able to browse web sites send and send email through
computers
that may have no connection outside the school.
Design and Research Center: This site has an alphabetical listing of networking terms, networking categories, and other networking resources. This site also includes information on cyber terrorism and security and encryption issues.
Sites-topology
images courtesy
of netc.org/
-table
of LAN technologies
courtesy of devius.cs.uiuc.edu/