Network Topology

Network Topology: The specific physical, i.e., real, or logical, i.e., virtual, arrangement of the elements of a network. Note 1: Two networks have the same topology if the connection configuration is the same, although the networks may differ in physical interconnections, distances between nodes, transmission rates, and/or signal types. Note 2: The common types of network topology are illustrated [refer to the figure on this page] and defined in alphabetical order below:


bus topology: A network topology in which all nodes, i.e., stations, are connected together by a single bus.
fully connected topology: A network topology in which there is a direct path (branch) between any two nodes. Note: In a fully connected network with n nodes, there are n(n-1)/2 direct paths, i.e., branches. Synonym fully connected mesh network.
hybrid topology: A combination of any two or more network topologies. Note 1: Instances can occur where two basic network topologies, when connected together, can still retain the basic network character, and therefore not be a hybrid network. For example, a tree network connected to a tree network is still a tree network. Therefore, a hybrid network accrues only when two basic networks are connected and the resulting network topology fails to meet one of the basic topology definitions. For example, two star networks connected together exhibit hybrid network topologies. Note 2: A hybrid topology always accrues when two different basic network topologies are connected.
linear topology: See bus topology.
mesh topology: A network topology in which there are at least two nodes with two or more paths between them.
ring topology: A network topology in which every node has exactly two branches connected to it.
star topology: A network topology in which peripheral nodes are connected to a central node, which rebroadcasts all transmissions received from any peripheral node to all peripheral nodes on the network, including the originating node. Note 1: All peripheral nodes may thus communicate with all others by transmitting to, and receiving from, the central node only. Note 2: The failure of a transmission line, i.e., channel, linking any peripheral node to the central node will result in the isolation of that peripheral node from all others. Note 3: If the star central node is passive, the originating node must be able to tolerate the reception of an echo of its own transmission, delayed by the two-way transmission time, i.e., to and from the central node, plus any delay generated in the central node. An active star network has an active central node that usually has the means to prevent echo-related problems. (188)
tree topology: A network topology that, from a purely topologic viewpoint, resembles an interconnection of star networks in that individual peripheral nodes are required to transmit to and receive from one other node only, toward a central node, and are not required to act as repeaters or regenerators. (188) Note 1: The function of the central node may be distributed. Note 2: As in the conventional star network, individual nodes may thus still be isolated from the network by a single-point failure of a transmission path to the node. Note 3: A single-point failure of a transmission path within a distributed node will result in partitioning two or more stations from the rest of the network.




Unshielded Twisted Pair (UTP)-Twisted pair cables were first used in telephone systems by Bell in 1881 and by 1900 the entire American network was twisted pair, or else open wire with similar arrangements to guard against interference. The majority of data or Internet connections use those wires. UTP cables are not shielded. This lack of shielding results in a high degree of flexibility as well as rugged durability. UTP cables are found in many ethernet networks and telephone systems.
Maximum Distance, 600 meters. Wiring, Unshielded Twisted Pair Category 5 or better.
UTP-Unshielded Twisted Pair. Normally UTP contains 8 wires or 4 pair. 100 meter maximum length. 4-100 Mbps speed.
Shielded Twisted Pair (STP)-STP cabling includes metal shielding over each individual pair of copper wires. This type of shielding protects cable from external EMI (electromagnetic interferences). e.g. the 150 ohm shielded twisted pair cables defined by the IBM Cabling System specifications and used with token ring networks.
STP-Shielded twisted pair. 100 meter maximum length. 16-155 Mbps speed. Lower electrical interference than UTP.

Optical fiber-An optical fiber (or fibre) is a glass or plastic fiber designed to guide light along its length by confining as much light as possible in a propagating form. In fibers with large core diameter, the confinement is based on total internal reflection. In smaller diameter core fibers, (widely used for most communication links longer than 200 meters) the confinement relies on establishing a waveguide. Fiber optics is the overlap of applied science and engineering concerned with such optical fibers. Optical fibers are widely used in fiber-optic communication, which permits transmission over longer distances and at higher data rates than other forms of wired and wireless communications. They are also used to form sensors, and in a variety of other applications.



FireWire is Apple Inc.'s brand name for the IEEE 1394 interface (although the 1394 standard also defines a backplane interface). It is also known as i.Link (Sony’s name). It is a personal computer (and digital audio/digital video) serial bus interface standard, offering high-speed communications and isochronous real-time data services. FireWire has replaced Parallel SCSI in many applications, due to lower implementation costs and a simplified, more adaptable cabling system. IEEE 1394 has been adopted as the High Definition Audio-Video Network Alliance (HANA) standard connection interface for A/V (audio/visual) component communication and control[1]. FireWire is also available in wireless, fibre optic and coaxial versions using the isochronous protocols. Wireless FireWire is being integrated into the WiMedia Alliance's WiMedia Ultra-Wideband (UWB) standard.













add-in card
Turn off and unplug your PC, then remove the cover. To avoid static damage, wear an antistatic wrist strap while working inside your PC. Find a free PCI slot, carefully insert the network card into it, and fasten it down with a screw. When you restart your PC, Windows should automatically detect the card. Follow the manufacturer's directions for installing the driver.
USB adapter (phone-line and wireless networks). Plug the USB connector into a free USB port. Windows should automatically detect the unit. Follow the manufacturer's directions for installing the driver.

PC Card. With your notebook running Windows, insert the PC Card into an unused PC Card slot. Windows should automatically detect the unit. Follow the manufacturer's directions for installing the driver.

Hook up your router
If you have a broadband Internet connection, you will need to hook up the router/firewall to the cable modem or DSL box, using the cable that came with the router.

Hook up the wires
If you're using a standard network, plug a Category 5 network cable from each PC network card (A) into your hub or switch (B). Do the same with your router/firewall if you have one. For a phone-line network, plug one end of a phone cable into the correct jack on the card (C) or USB adapter (usually there's an additional jack for hooking up a phone), and plug the other end into a phone jack. With a wireless network, as the name implies, you normally don't need to run any wires unless you're using a router or access point to integrate it with a wired network.

Install the software
In addition to installing the drivers for the network adapters, you'll probably have to install product-specific software in order to set up the hardware and to customize the settings. In each instance, follow the manufacturer's directions.

Get connected
Test your network to make sure everything is talking to everything else. If you can't access the Internet or communicate with other PCs on your network, first check your network product manual or the maker's Web site. Alternatively, go to Start, Help, select Network Troubleshooter





Wifi "wireless fidelity". The term "wifi" refers to certain kinds of wireless local area networks, or WLAN (as opposed to LAN, or computers that are networked together with wires).
Travelers with PDA's (like Blackberries) and other handheld devices or laptops with wireless cards can connect to the internet via wifi. A wireless card is like a modem without a phone line (like an airport card in a Mac).

Travelers care what wifi is because with wifi, travelers can log on to the internet anywhere and find a hostel, or a map and directions, check email, download music and everything else you do with a computer connected to the internet at home.