NIC (Network Interference Card)
The most important PC device is the network interface card (NIC). Each computer on the network, including the servers, is required to have one installed. It is the NIC that provides connectivity between the PC and the network's physical medium, the copper or fiber-optic cable.
Most of the new motherboards available today for PCs and servers have the network interface card integrated with the motherboard. Older computers and some newer computers do not provide onboard network interfaces which will equire a NIC to be added.NICs provide computers with a connection to the network, but they also handle an important data-conversion function. Data travels in parallel on the PCI's bus system, but the network medium demands a serial transmission. The transceiver, a transmitter and receiver, on the NIC has the ability to move data from parallel to serial and vice versa. This isn't any different than an automobiles travelling down a multi-lane superhighway where all lanes must merge into one lane.
Network interface cards also have the ability of supplying a basic addressing system that can be used to get data from one computer to another on the network. The hardware or MAC address is burned into a ROM chip on the NIC. This is referred to as the MAC address because the Media Access Control (MAC) layer is acutally a sublayer of the OSI model's Data Link layer.
HUB
A common connection point for devices in a network. Hubs are commonly used to connect segments of a la. A hub contains multiple ports When a packets arrives at one port, it is copied to the other ports so that all segments of the LAN can see all packets.
A passive hub serves simply as a conduit for the data, enabling it to go from one device (or segment) to another. So-called intelligent hubs include additional features that enables an administrator to monitor the traffic passing through the hub and to configure each port in the hub. Intelligent hubs are also called manageable hubs. A third type of hub, called a switching hub actually reads the destination address of each packet and then forwards the packet to the correct port.
SWITCH
A network switch is a small hardware device that joins multiple computers together within one. Technically, network switches operate at layer two (Data Link Layer) of the OSI MODEL.
Network switches appear nearly identical to NETWORK HUB, but a switch generally contains more intelligence (and a slightly higher price tag) than a hub. Unlike hubs, network switches are capable of inspecting data PACKETS as they are received, determining the source and destination device of each packet, and forwarding them appropriately. By delivering messages only to the connected device intended, a network switch conserves NETWORK BANDWIDTH and offers generally better performance than a hub.
ROUTER
Routers are physical devices that join multiple wired or wireless networks together. Technically, a wired or wireless router is a Layer 3 gateway, meaning that the wired/wireless router connects networks (as gateways do), and that the router operates at the network layer of the OSI model.
Home networkers often use an Internet Protocol (IP) wired or wireless router, IP being the most common OSI network layer protocol. An IP router such as a DSL or cable modem broadband router joins the home's local area network (LAN) to the widearea network (WAN)of the Internet.
BRIDGE
A bridge device filters data traffic at a network boundary. Bridges reduce the amount of traffic on a LAN by dividing it into two segments.
Bridges operate at the data link layer (Layer 2) of the OSI model. Bridges inspect incoming traffic and decide whether to forward or discard it. An Ethernet bridge, for example, inspects each incoming Ethernet frame - including the source and destination MAC addresses, and sometimes the frame size - in making individual forwarding decisions.
Bridges serve a similar function as switches, that also operate at Layer 2. Traditional bridges, though, support one network boundary, whereas switches usually offer four or more hardware ports. Switches are sometimes called "multi-port bridges" for this reason.
REPEATER
Network repeaters regenerate incoming electrical, wireless or optical signals. With physical media like Ethernet or WI, FI data transmissions can only span a limited distance before the quality of the signal degrades. Repeaters attempt to preserve signal integrity and extend the distance over which data can safely travel.
Actual network devices that serve as repeaters usually have some other name. Active hubs, for example, are repeaters. Active hubs are sometimes also called "multiport repeaters," but more commonly they are just "hub" Other types of "passive hubs" are not repeaters. In Wi-Fi, access point function as repeaters only when operating in so-called "repeater mode."
SWITCH
A network switch is a small hardware device that joins multiple computers together within one. Technically, network switches operate at layer two (Data Link Layer) of the OSI MODEL.
Network switches appear nearly identical to NETWORK HUB, but a switch generally contains more intelligence (and a slightly higher price tag) than a hub. Unlike hubs, network switches are capable of inspecting data PACKETS as they are received, determining the source and destination device of each packet, and forwarding them appropriately. By delivering messages only to the connected device intended, a network switch conserves NETWORK BANDWIDTH and offers generally better performance than a hub.
ROUTER
Routers are physical devices that join multiple wired or wireless networks together. Technically, a wired or wireless router is a Layer 3 gateway, meaning that the wired/wireless router connects networks (as gateways do), and that the router operates at the network layer of the OSI model.
Home networkers often use an Internet Protocol (IP) wired or wireless router, IP being the most common OSI network layer protocol. An IP router such as a DSL or cable modem broadband router joins the home's local area network (LAN) to the widearea network (WAN)of the Internet.
BRIDGE
A bridge device filters data traffic at a network boundary. Bridges reduce the amount of traffic on a LAN by dividing it into two segments.
Bridges operate at the data link layer (Layer 2) of the OSI model. Bridges inspect incoming traffic and decide whether to forward or discard it. An Ethernet bridge, for example, inspects each incoming Ethernet frame - including the source and destination MAC addresses, and sometimes the frame size - in making individual forwarding decisions.
Bridges serve a similar function as switches, that also operate at Layer 2. Traditional bridges, though, support one network boundary, whereas switches usually offer four or more hardware ports. Switches are sometimes called "multi-port bridges" for this reason.
REPEATER
Network repeaters regenerate incoming electrical, wireless or optical signals. With physical media like Ethernet or WI, FI data transmissions can only span a limited distance before the quality of the signal degrades. Repeaters attempt to preserve signal integrity and extend the distance over which data can safely travel.
Actual network devices that serve as repeaters usually have some other name. Active hubs, for example, are repeaters. Active hubs are sometimes also called "multiport repeaters," but more commonly they are just "hub" Other types of "passive hubs" are not repeaters. In Wi-Fi, access point function as repeaters only when operating in so-called "repeater mode."
