In the smooth functioning of networks, many hardware devices play an important role. These hardware devices, or in other words, Networking hardware may also be known as network equipment or computer networking devices. Hence we’ll be studying a few of them in the following sections. All these devices facilitate the use of a computer network. Specifically, they mediate data in a computer network.
So that would be all my friends. Please check out my other posts if you found this one interesting! Take care :)
MODEM
A Modem is a computer peripheral that allows you to connect and communicate with other computers via telephone lines. In other words, modems allow you to combine the power of your computer with the global reach of the telephone system.
Because ordinary telephone lines cannot carry digital information, a modem changes the digital data from your computer into analog data, a format that can be carried by telephone lines. In a similar manner, the modem receiving the call then changes the analog signal back into digital data that the computer can digest. This shift of digital data into analog data and back again, allows two computers to “speak” with one another. Called modulation/ demodulation, this transformation of signals if how the modem received its name.
Modems come in two cariants:
- Internal Modem: the modems that are fixed within the computer
- External Modem: the modems that are connected externally to a computer as other peripherals are connected.
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| External MODEM |
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| Internal MODEM |
RJ-45
RJ-45 is short for Registered Jack – 45. RJ-45 is an 8 wire connector, which is commonly used to connect computers on LANs i.e. Local Area Networks especially Ethernets.
The RJ-45 connector looks very much similar to standard telephone connector (RJ-11 Connector) but it’s wider than RJ-11 as its houses 8 wires instead of 4. RJ-45 connectors are used to connect computers to Ethernet LANs.
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| RJ-45 Connector |
Ethernet Card
Ethernet is a LAN architecture developed by Xerox Corp. along with BEC and Intel. Ethernet uses either a bus or star topology and supports data transfer rates of up to 10 Mbps. The computers that are part of Ethernet have to install a special card Ethernet Card.
An Ethernet Card contains connections for Coaxial or Twisted Pair Cables (or both). If it is designed for Coaxial Cable, the connection will be BNC. If it’s designed for Twisted Pair it’ll have a RJ-45 Connection. Some Ethernet cards also contain an AUI Connector. This can be used to attach Coaxial, Twisted Pair and Fiber Optics Cable to an Ethernet Card.
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| Ethernet Network Interface Card (NIC) with RJ-45 slot (right) and BNC slot (left) |
Hub
A hub is a hardware device used to connect several hardware devices together. A hub that contains multiple, independent but connected modules of network and inter-networked equipment can also be called as a Concentrator. A Concentrator is a device which provides a central connection point for cables from workstations, servers and peripherals. In a star topology, twisted pair wire is run from each workstation to a central concentrator.
Basically, Hubs are multi-slot concentrators into which a number of multi-port cards can be plugged to provide additional access as the network grows in size. Hubs can be either Passive or Active.
- Passive: Allow the signal to pass from one computer to another without any change.
- Active: Electrically amplify the signal as it moves from one connected device to another. Active concentrators are used like repeaters to extend the length of a network.
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| Ethernet Hub |
Switch
A switch is a device that is used to segment networks into different sub-networks called subnets or LAN segments. Segmenting the network into smaller subnets prevents traffic overloading in a network. A switch is responsible for filtering i.e., transforming data in a specific way and forwarding packets between LAN segments. Switch supports any packet protocol. LANs that are segmented through switches are called switched LANs. In the case of Ethernet LANs, they are called switched Ethernet LANs.
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| Network Switch |
Repeater
A Repeater is a device that amplifies a signal being transmitted on the network. It is used in long network which exceed the maximum rated distance for a single run.
Over distance, the cables connecting a network lose the signal transmitted. If the signal degrades too much, it fails to reach the destination. Or if it does arrive, the degradation of the message makes it useless. Repeaters can be installed along the way to ensure the data packets reach their destination.
Repeaters are of two kinds:
- Amplifier: It merely amplifies all incoming signals over the network. However it amplifies both the signal and any concurrent noise.
- Signal Repeater: It collects the inbound packet and then retransmits the packet as if it were starting from the source station.
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| Network Repeater; Image Courtesy: wiki.microtik.com |
Bridge
A bridge is a device that lets you link two networks together. Bridges are smart enough to know which computers are on which side of the bridge, so they only allow those messages that need to get to the other side to cross the bridge. This improves performance on both sides of the bridge. As a packet arrives at the bridge, the bridge examines the physical destination address of the packet. The bridge then decides whether or not to let the packet cross.
Router
A device that works like a bridge but can handle different protocols is known as a Router. For example, a router can link an Ethernet to a Mainframe. If the destination is unknown to a Router it sends the traffic (bound to unknown destination) to another Router (using logical addresses) which knows the destinations. A Router differs from a bridge in a way that former uses logical addresses and the latter uses physical addresses.
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| Wireless + Ethernet Router |
Gateway
A gateway is a device that connects dissimilar networks. A gateway operates at the highest layer of network abstraction. It expands the functionality of routers by performing data translation and protocol conversion. It is needed to convert Ethernet traffic from the LAN, to SNA (Systems Network Architecture) traffic on a legacy system. It then routes the SNA traffic to the mainframe. When the mainframe answers, the reverse process occurs.
A gateway is actually a node on a network that serves as an entrance to another network. In enterprises, the gateway is the computer that routes the traffic from a workstation to the outside network that is serving the Web Pages. In homes, the gateway is the ISP that connects to the Internet.
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| Network Gateway |
So that would be all my friends. Please check out my other posts if you found this one interesting! Take care :)
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