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Sunday, January 30, 2011

Network Devices



Network Devices


NIC
Stands for "Network Interface Card." Pronounced "nick," this is the card that physically makes the connection between the computer and the network cable. These cards typically use an Ethernet connection and are available in 10, 100, and 1000 Base-T configurations. A 100 Base-T card can transfer data at 100 Mbps. The cards come in ISA and PCI versions and are made by companies like 3Com and LinkSys. So if you want to connect your computer to a network, you better get yourself a NIC.

ROUTER
A network device that forwards packets from one network to another. Based on internal routing tables, routers read each incoming packet and decide how to forward it. To which interface on the router outgoing packets are sent may be determined by any combination of source and destination address as well as current traffic conditions (load, line costs, bad lines, etc.).


SWITCH
A switch is used to network multiple computers together. Switches made for the consumer market are typically small, flat boxes with 4 to 8 Ethernet ports. These ports can connect to computers, cable or DSL modems, and other switches. High-end switches can have more than 50 ports and often are rack mounted.

Switches are more advanced than hubs and less capable than routers. Unlike hubs, switches can limit the traffic to and from each port so that each device connected to the switch has a sufficient amount of bandwidth. For this reason, you can think of a switch as a "smart hub." However, switches don't provide the firewall and logging capabilities that routers do. Routers can often be configured by software (typically via a Web interface), while switches only work the way the hardware was designed.

The term "switch" can also be used to refer to a small lever or button on computer hardware. And while it has nothing to do with computers, "riding switch" means riding backwards in skateboarding and snowboarding.

BRIDGE
 In communications networks, a device that (a) links or routes signals from one ring or bus to another or from one network to another, (b) may extend the distance span and capacity of a single LAN system, (c) performs no modification to packets or messages, (d) operates at the data-link layer of the OSI--Reference Model (Layer 2), (e) reads packets, and (f) passes only those with addresses on the same segment of the network as the originating user. (188) 2. A functional unit that interconnects two local area networks that use the same logical link control procedure, but may use different medium access control procedures. 3. A balanced electrical network, e.g. , a Wheatstone bridge. Note: A bridge may be used for electrical measurements, especially resistances or impedances..




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