DATA COMMUNICATIONS NETWORKS

Data Communications

* Data Communications
The movement of computer information from one point to another by means of electrical or optical transmission systems.
Such systems are often called data communications networks.

* Telecommunications
Includes the transmission of voice and video as well as data.

Components of a Network

* Server (or Host computer)
Central computer in the network, storing data or software that can be accessed by the clients.

* Client
The input/output hardware device at the other end of a communications circuit.

* Circuit
The pathway through which the messages travel.

Basic Hardware Components

All networks are made up of basic hardware building blocks to interconnect network nodes, such as Network Interface Cards (NICs), Bridges, Hubs, Switches, and Routers. In addition, some method of connecting these building blocks is required, usually in the form of galvanic cable (most commonly Category 5 cable). Less common are microwave links (as in IEEE 802.12) or optical cable ("optical fiber"). An Ethernet card may also be required.

Network interface cards

A network cards, network adapter, or NIC (network interface card) is a piece of computer hardware designed to allow computers to communicate over a computer network.

Hubs

A network hub contains multiple ports. When a packet arrives at one port, it is copied unmodified to all ports of the hub for transmission. The destination address in the frame is not changed to a broadcast address.

Router

is a device that interconnects two or more computer networks, and selectively interchanges packets of data between them. Each data packet contains address information that a router can use to determine if the source and destination are on the same network.

NETWORK TOPOLOGIES

Mesh Topology-Devices are connected with many redundant interconnections between network nodes. In a true mesh topology every node has a connection to every other node in the network.

Star Topology-All devices are connected to a central hub. Nodes communicate across the network by passing data through the hub.

Bus Topology-All devices are connected to a central cable, called the bus or backbone.

Bus Topology-All devices are connected to one another in the shape of a closed loop, so that each device is connected directly to two other devices, one on either side of it.

Tree Topology -A hybrid topology. Groups of star-configured networks are connected to a linear bus backbone.

COLOR-CODE STANDARDS

Again, please bear with me... Let's start with simple pin-out diagrams of the two types of UTP Ethernet cables and watch how committees can make a can of worms out of them. Here are the diagrams: