Network hardware

Network hardware

How does workstation connect with the network?

Wired and wireless connections

Wired connection. It uses NIC. Computers can be connected through Ethernet cables which connect to the Ethernet port.
Wireless connection. Computers can make a wireless connection if they have a wireless NIC. They connect with wireless access point or wireless router.
A network interface card (NIC) is a circuit board installed in a computer that provides a dedicated network connection to the computer.  
Wireless access points (APs or WAPs) are networking devices that allow     Wi-Fi devices to connect to a wired network.
But what if I have three computers?

Computers need networking hardware in order to connect to each other. Routershubsswitches and bridges are all pieces of networking equipment that can perform slightly different tasks. A router can often incorporate hubs, switches and wireless access within the same hardware.

Hub

Hubs extend the range of a network by receiving data on one port and then regenerating the data and sending it out to all other ports. 

A hub can also function as a repeater. A repeater extends the reach of a network because it rebuilds the signal, which overcomes the effects of data degradation over distance. The hub can also connect to another networking device, like a switch or router that connects to other sections of the network.

Hubs are used less often today because of the effectiveness and low cost of switches. Hubs do not segment network traffic, so they decrease the amount of available bandwidth for all devices connected to them. In addition, because hubs cannot filter data, a lot of unnecessary network traffic constantly moves between all the devices connected to it.

Bridge

LANs are often divided into sections called segments, similar to the way a company is divided into departments, or a school is divided into classes. The boundaries of segments can be defined using a bridge. 

A bridge connect two LAN segments and filters network traffic between LAN segments. 

Bridges keep a record of all the devices on each segment to which the bridge is connected. When the bridge receives a frame, the bridge examines the destination address to determine if the frame is to be sent to a different segment or dropped. The bridge also helps to improve the flow of data by keeping frames confined to only the segment to which the frame belongs.

Switch

Switches are sometimes called multiport bridges. A switch has several ports, depending on how many network segments are to be linked. 
Like a hub, the speed of the switch determines the maximum speed of the network. However, switches filter and segment network traffic by sending data only to the device to which it is sent. This provides higher dedicated bandwidth to each device on the network.

Switches maintain a switching table. The switching table contains a list of all MAC addresses on the network, and a list of which switch port can be used to reach a device with a given MAC address. When a frame arrives that is destined for a particular MAC address, the switch uses the switching table to determine which port to use to reach the MAC address. The frame is forwarded from the port to the destination. By sending frames out of only one port to the destination, other ports are not affected.

Modem

A modem is an electronic device that connects to the Internet via an ISP (Internet Service Provider). 

The modem converts digital data to analog signals for transmission over a phone line. Because the analog signals change gradually and continuously, they can be drawn as waves. In this system, the digital signals are represented as binary bits. The digital signals must be converted to a waveform to travel across telephone lines. They are converted back to bits by the receiving modem so that the receiving computer can process the data.

Wireless access point

Wireless access points provide network access to wireless devices, such as laptops and tablets. 

The wireless access point uses radio waves to communicate with the wireless NIC in the devices and other wireless access points. An access point has a limited range of coverage. Large networks require several access points to provide adequate wireless coverage. A wireless access point provides connectivity only to the network, while a wireless router provides additional features, such as assigning IP addresses.

Routers

Routers connect networks to each other. Switches use MAC addresses to forward a frame within a single network. Routers use IP addresses to forward packets to other networks. A router can be a computer with special network software installed or a device built by network equipment manufacturers.

Firewall 

Hardware firewalls, such as integrated routers, protect data and equipment on a network from unauthorized access. A hardware firewall is a free-standing unit that resides between two or more networks, as shown in the figure. It does not use the resources of the computers it is protecting, so there is no impact on processing performance.

A firewall should be used in addition to security software. A firewall resides between two or more networks and controls the traffic between them as well as helps prevent unauthorized access. Firewalls use various techniques for determining what is permitted or denied access to a network segment.

Considerations when selecting a hardware firewall include:

  • Space - Free standing and uses dedicated hardware
  • Cost - Initial cost of hardware and software updates can be costly
  • Number of computers - Multiple computers can be protected
  • Performance requirements - Little impact on computer performance
     
Категория: Types of networks | Добавил: bzfar77 (29.07.2020)
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