networking devices

networking devices are used to interconnect the systems to communicate themselves.

 there are 5 mostly used devices. they are 

1. repeater
2. hub
3. bridge
4. switch
5. router

1.repeater:

    A repeater connects two segments of your network cable. It retimes and regenerates the signals to proper amplitudes and sends them to the other segments. When talking about, ethernet topology, you are probably talking about using a hub as a repeater. Repeaters require a small amount of time to regenerate the signal. This can cause a propagation delay which can affect network communication when there are several repeaters in a row. Many network architectures limit the number of repeaters that can be used in a row. Repeaters work only at the physical layer of the OSI network model. repeaters are not important to learn. this devices are outdated.

2.hub:

essentially repeaters operating at bit levels: repeat received bits on one

interface to all other interfaces. Hubs can be arranged in a hierarchy (or multi-tier design), with backbone hub at its top. Each connected LAN referred to as LAN segment. Hubs do not isolate collision domains: node may collide with any node residing at any segment in LAN.

Hub Advantages:

*simple, inexpensive device

*Multi-tier provides graceful degradation: portions of the LAN continue to operate if one hub malfunctions

*extends maximum distance between node pairs

  (100m per Hub).

hub is also outdated.

   

limitations:

*single collision domain results in no increase in max throughput multi-tier throughput same as single segment
throughput.

*individual LAN restrictions pose limits on number of nodes in same collision domain and on total allowed geographical coverage.
*cannot connect different Ethernet types (e.g., 10BaseT and 100baseT)

3.bridges:

Bridges are used to divide larger networks into smaller sections. They do this

by sitting between two physical network segments and managing the flow of

data between the two. By looking at the MAC address of the devices con-

nected to each segment, bridges can elect to forward the data (if they believe

that the destination address is on another interface), or block it from cross-

ing (if they can verify that it is on the interface from which it came). Figure

shows how a bridge can be used to segregate a network.

switches and routers important to learn as the networking engineers. so read complete posts on switches and routers.