Networks

Morgan Computer Service can solve you networking needs. We want to supply you with some background informtion on what networks are, what tools are used in networks, and how many different arragements they can be set up and designed

Network setups:

Bus.
A type of network in which all tie devices are connected in a line to a single cable. A bus network has two distinct ends. All devices which attached to a bus network have equal access to it and they can see all the messages that are put on to the network. Each device determines which messages are intended for it alone, and selects those.

Star.
A network layout or design in which each node is connected to a central hub. The hub establishes, maintains and terminates all connections between the nodes. In a LAN, the hub is likely to be a workstation, whereas in larger multi-point networks the hub is more likely to a multiplexer.

Ring.
A layout scheme in which the network takes the form of a closed loop with the devices attached into the ring. Every workstation is linked to two others, one on each side. All data is passed from node to node in one direction only, each PC acting as a repeater for the next one in the loop. Response time is determined by the number of stations on the ring - the more there are, the slower it works. If one PC fails, the loop is broken, though most rings have self-healing capacity to reconfigure and continue operation. IBM's Token passing ring ensures that the failed station is removed and its neighbors are then directly connected.

Network Devices:

Transceiver
(transmitter/receiver) or MAU (Medium Attachment Unit). Comprises of hardware circuitry that provides the correct electrical or optical connection between the computer and IEEE 802.3 LAN media. Since MAUs typically support only one type of network medium, a choice of MAUs is available to support different media. It detects carrier and collision activity, passing the information to the Computer. It can be a standalone unit or incorporated in a circuit board inside the computer.

Repeater.
A device that extends the maximum length of cable that can be used in a single network. In fiber networks, it is an optoelectrical module that receives an optical signal and converts it into an electrical form. Works in Level One Physical Layer of OSI model.

Converter.
A repeater that also converts from one media type to another, such as from fiber to copper. Often called a media adapter.

Hub.
The center of a star topology network or cabling system. A multi-node network topology that has a central multiplexer with many nodes feeding into and through the multiplexer or hub. The other nodes do not usually directly interconnect. LAN hubs are increasingly popular with the growth of structured cabling and the need for LAN management. Essentilly a multi-port repeater.

Bridge.
Device connecting two separate networks at the OSI Data Link Layer (Level Two Media Access Control Layer). Once bridging is accomplished, the bridge makes interconnected LANs look like a single LAN, passing data between the networks and filtering local traffic. Bridges connect networks using dissimilar protocols and do not interpret the data they carry. They control network traffic and security, filtering where necessary to boost network, performance and contain sensitive data to particular LAN areas.

Switch.
Essentially a multi-port bridge. Creates multiple independent connections between separate between separate segments, allowing multiple parallel data exchanges.

Router.
Network interconnector device operating at OSI Network Layer (Level Three) that supports a particular Network Layer protocol and related stack, such as TCP/IP, DecNet, XNS, OSI IP, IPX. These days routers tend to support multiple protocols by a variety of methods, such as Protocol Independent Routing. A router can be used to link LANs together locally or remotely as part of a WAN. A network built using routers is often termed an internetwork.

Gateway.
Generic term often used for many routing and/or translating devices.
Protocols
TCP/IP.
The suite of protocols developed and used by DARPA and the US DOD. They build up to Layer Four of the ISO OSI model, but there is no direct correspondence layer for layer.
IPX/SPX. Novell.

ATM
(Asynchronous Transfer Mode) A cell- based data transfer technique in which channel demand determines packet allocation. ATM offers fast packet technology, real time, demand led switching for efficient use of network resources. It is also the generic termadopted by ANSI and the ITU-TS to classify cell relay technology within the realm of broadband WANs, specifically B-ISDN. In ATM, units of data are not time related to each other and, as part of the B-ISDN standard, is specified for digital transmission speeds from34Mbit/s to 622Mbit/s. IBM currently offers ATM at a non standard 25Mbit/s format. ATM will be the high band width networking standard of the decade.