Networking Devices

Networking devices are component used to connect computer or other electronic devices together so that they can share data and other resources. Devices which are used to create a LAN are most common networking devices. These devices also known as communication device.

Different networking devices have different roles  in a computer network. These network devices also work at different segments of a computer network performing different works.

NIC (Network Interface Card):

NIC is the primary and most important networking device, without this device networking cannot be done. NIC allows our PC to connect and communicate with other PC or networking device through a medium or we can say that a NIC connect a computer to a network with a dedicated full-time connection. Most of computer & workstation are inbuilt NIC present on the motherboard. NIC convert parallel data stream into serial data stream and serial data stream into parallel data stream. Every NIC has a unique 48-bit MAC address.

There are different types of network interface card according to network design and required medium.

Modem:

A modem is a networking device that convert analog signals to digital signal and digital signals to analog signal for two-way network communication. The term  MODEM is short for MOduletor-DEModulater.

Conversion of one type of signals to another is called modulation, their re-conversion to the original type is called demodulation. A modem is a hardware device that allows a computer to send and receive information over telephone lines by converting digital data into an analog signal used on phone lines.

The basic modulation techniques used by a modem to convert digital data to analog signals are :

 

• Amplitude shift keying (ASK).

• Phase shift keying (PSK).

• Differential PSK (DPSK).

• Frequency shift keying (FSK).

 Network HUB: 

A network HUB  is a device which is used to connect multiple network host into a network. HUB centralize network traffic through a single connecting point.

 A HUB is a Layer-1 device works on physical layer of OSI modal. Hub receive data packet from one host and broadcast it to all connected node including the host who send this data  and the destination node whom the packet is intended, claims the packet. Because of this broadcast mechanism hubs are not safe and secure. The point to remember that Hub always do Broadcast.

Switch:

A network Switch is a device used to connect multiple computer or host to a single network like a Hub but have more added feature and intelligence than a HUB.

Switch takes data packet from one connected port and forward it to the specific destination port. Unlike hub, network switches are capable of inspecting incoming messages, are they are received and direct them to a specific communications port. This technology is called packet switching. A switch determines the source and destination addresses of each packet and forwards data only to the specific devices. Switch uses MAC address of each connected host for reliable data transfer between sender & receiver. It simply looks at each packet or data unit and determines physical address (MAC address).Switch is a Layer-2 device works on Data-Link layer of OSI modal.

The network switches can be categorized into two category:

Modulator Switch:

In a modulator switch some expansion slots are available so we can add some expansion module Required for our network.

Fixed Switch

These Switches have fixed numbers of port available and typically are not expandable. These switches are available in various size and number of ports according to network requirement.

We can categorize fixed switches into two sub category

1. Unmanaged Switch                    2)   Managed Switch

We can batter understand different types of switches by the following diagram:

Unmanaged Switch: 

These switches are most commonly used in home or small office network. Unmanaged switches works on plug & play mechanism, very simple to use and no need of any configuration. If we need to connect any device to our network just connect it to any available port on switch and the device will instantly be connected to whole network.

Managed Switch:

Managed switches provide all the features of an unmanaged switch and also provide additional capability to configure, manage and monitor our network. The managed switch gives us complete control over how the data will travel on the network and the data will reach. We can sub-classify our network in VLAN to control and make the network more secure. SNMP (Simple Network Management Protocol) has been managed to monitor network connected computers.

 Managed switches make the network more secure by using the port-security feature. Port security feature enables the user to control the access of the port on the basis of the MAC address. By default, the Port Security feature has been disabled on the managed switch, which has to be manually enabled.

 Console port & auxiliary port are available on each managed switch for network configuration. Console port is the primary port for manual configuration. Managed switches can also be configured with remote access. Switch (L2-Switch) layer-2 or OSI model works on the data-link layer.

Managed switches are categorized into two category:

1. Layer-2 Switch
2. Layer-3 Switch

Layer-3 switches provide all the features of the switch-2 switch and provide additional capability to work on Layer-3 protocols. Layer 3 switches can work on Layer-3 protocols like router, while Layer-2 switches are not capable of working on Layer-3 protocols. L2 switches can work only on the data link layer, while L3 switches can work on both the data-link layer and the network layer of the OSI model.

Repeaters:

Repeater is a networking device that amplifies the received signal and forward it to other end. In other terms, we can think that repeater receive signal and re-transmits it at a higher level or higher power so that the signal can cover longer distance. Repeater connects two segment of network cable. Repeater receives signal from one segment and regenerates it to proper amplitudes and sends them to the other segment. Repeater requires a small amount of time to regenerates signals so if there are several repeater in network it can cause a delay which can affect network communication in network. Repeaters works on Layer-1 or Physical layer of OSI modal.

 Bridge:

A bridge is a networking device that creates a single network from different network segment. A bridge connect a local area network to other local area network which uses the same protocols ( Ethernet or Token-ring). A bridge typically works on frame-by-frame basis of data. A bridge examines each message on a LAN, passing those known to be within the same LAN, and forwarding those known to be on the other interconnected LAN.

Router:

A router is a networking device which is used to connect two or more different network together. Router transmit data packets between computer networks. Router perform the traffic direction on the internet.  a router acts as a dispatcher as it decides which way to send each information packet based on forwarding table or routing table of connected network, or it decides that which route is best to send packets.

 A router may create or maintain a table of the available routes and their conditions and use this information along with distance and cost algorithms to determine the best route for a given packet. Routers use headers and forwarding tables to determine the best path for forwarding the packets, and they use protocols such as ICMP to communicate with each other and configure the best route between any two hosts.

Wireless Access-Point:  Wireless access points are special-purpose networking devices that allows a Wi-Fi compliant device to connect to a wired network. The WAP usually connects to a router (via a wired network) as a standalone device, but it can also be an integral component of the router itself . Access points act as a central transmitter and receiver of wireless radio signals.

Each access point can serve multiple users within a defined network area; as people move beyond the range of one access point, they are automatically handed over to the next one. Mainstream wireless Access points support Wi-Fi and are most commonly used to support public Internet hotspots and other business networks where larger buildings and spaces need wireless coverage.

You can download these notes from google drive, use this link-

https://drive.google.com/open?id=0B6Ov-Oe4YuYUYTc4MGVXMl9haG8