Network Devices

What is Network Devices ?

@ Networking hardware, also known as network equipment or computer networking devices, are electronic devices which are required for communication and interaction between devices on a computer network. 

@ These devices transfer data in a fast, secure and correct way over same or different networks. Network devices may be inter-network or intra-network. 

What is the use of networking device ?

Network devices or internetworking devices are used to establish a network connection inside the corporate environment.

What is collision ?

A network collision occurs when two network devices tries to transmit the same data at the same point of time. If network detect such as the collision, it discards both the packets received.

Direction of Data Transmission:-

--------------------------------

1. Simplex − A simplex modem can transfer data in only one direction, from digital device to network (modulator) or network to digital device (demodulator).
2. Half duplex − A half-duplex modem has the capacity to transfer data in both the directions but only one at a time.
3. Full duplex − A full duplex modem can transmit data in both the directions simultaneously.

Types of Network Devices:-

--------------------------

1. NIC_(Network Interface Card)
2. Repeter
3. HUB
4. Switch
5. Router
6. Modem
7. Bridge
8. Gateway

NIC_(Network Interface Card):-

------------------------------

1. Network Interface card
2. NIC has 48 bit address.
3. This address known as "Ethernet Address or MAC Address.
4. MAC stand for Media Access Control.
5. You can use hexadecimal format to write this address.
6. "getmac" or "ipconfig" is a command to check the the physical address or mac address in windows   o/s.
7. "ifconfig" command you can use to check the mac address in opensource operating system.
8. You can use wire & wireless ethernet card.
9. Wire ethernet card use RJ-45 port & wireless has no RJ-45 port

Speed of Ethernet:-

--------------------

A) Old Ethernet card use the maximum spped of 10 Mbps

B) Modern Ethernet card use the maximum speed of 100 Mbps

C) Some Ethernet card use the moe than 1 Gbps

Repeter:-

----------

1. A repeater is a device that operates only at the Physical Layer of OSI model.
2. A repeter can be used to increase the length of the network by eliminating the effect of attenuation on the signal.
3. It connect two segments of the same network, overcoming the distance limitations of the transmission media.
4. A repeater forwords every frame; it has no filtering capacity.
5. Since a signal loses strength as it passes along a cable, it is often necessary to boost the signal with a device called a repeater.

Example:- A good example of the use of repeaters would be in a local area network using a star topology with unshielded twisted-pair cabling. The length limit for unshielded twisted-pair cable is 100 meters. The most common configuration is for each workstation to be connected by twisted-pair cable to a multi-port active concentrator. The concentrator amplifies all the signals that pass through it allowing for the total length of cable on the network to exceed the 100 meter limit.

HUB:-

------

1. A central device that connects multiple computers on a single network.
2. A network hub has I/O ports that can be used to link several network devices together.
3. A signal would enter the hub through one port and the hub will broadcast it on every other port expect the port the data came in through.
4. The data sent in the form of frame.
5. A hub uses the "Physical Layer" of OSI model.
6. A hub can connect different nodes using the twisted pair cable or fiber optic cable.
7. HUB use in star topology.
8. Hub do not read any of the data passing through them and are not aware of their source or destination. It just broadcasts the packets out to all devices on the network including the one that originally sent the packet.

Types of Hub:-

--------------

1. Active Hub:- Amplify the electrical signal of incoming packets before broadcasting them out to the network.(2000 feet distance).Active hubs amplify and regenerate the incoming electrical signals before broadcasting them. They have their own power supply and serves both as a repeater as well as connecting centre. Due to their regenerating capabilities, they can extend the maximum distance between nodes, thus increasing the size of LAN.
2. Passive Hub:- Do not amplify the electrical signal of incoming packets before broadcasting them out to the network.(300 feet distance). Passive hubs connects nodes in a star configuration by collecting wiring from nodes. They broadcast signals onto the network without amplifying or regenerating them. As they cannot extend the distance between nodes, they limit the size of the LAN.
3. Intelligent Hub:- Regenrate the signals and perform network management and inteligent path selection. Intelligent hubs are active hubs that provide additional network management facilities. They can perform a variety of functions of more intelligent network devices like network management, switching, providing flexible data rates etc.

Switch:-

---------

1. A switch operates in the layer 2, i.e. data link layer of the OSI model.
2. It is an intelligent network device that can be conceived as a multiport network bridge.
3. Switch works on Star Topology.
4. It uses MAC addresses (addresses of medium access control sublayer) to send data packets to selected destination ports.
5. It uses packet switching technique to receive and forward data packets from the source to the destination device.
6. It is supports unicast (one-to-one), multicast (one-to-many), and broadcast (one-to-all) communications.
7. Transmission mode is full duplex, i.e. communication in the channel occurs in both the directions at the same time. Due to this, collisions do not occur.
8. Switches are active devices, equipped with network software and network management capabilities.
9. Switches can perform some error checking before forwarding data to the destined port.
10. The number of ports is higher – 24/48. 

• Unmanaged Switch:− These are inexpensive switches commonly used in home networks and small businesses. They can be set up by simply plugging in to the network, after which they instantly start operating. When more devices needs to be added, more switches are simply added by this plug and play method. They are referred to as  unmanaged since they do not require to be configured or monitored.

• Managed Switch:− These are costly switches that are used in organisations with large and complex networks, since they can be customized to augment the functionalities of a standard switch. The augmented features may be QoS (Quality of Service) like higher security levels, better precision control and complete network management. Despite their cost, they are preferred in growing organizations due to their scalability and flexibility. Simple Network Management Protocol (SNMP) is used for configuring managed switches.

• LAN Switch:− Local Area Network (LAN) switches connects devices in the internal LAN of an organization. They are also referred as Ethernet switches or data switches. These switches are particularly helpful in reducing network congestion or bottlenecks. They allocate bandwidth in a manner so that there is no overlapping of data packets in a network.

• PoE Switch:− Power over Ethernet (PoE) switches are used in PoE Gogabit Ethernets. PoE technology combine data and power transmission over the same cable so that devices connected to it can receive both electricity as well as data over the same line. PoE switches offer greater flexibility and simplifies the cabling connections.

• 
  

• 
  
  

Router:-

--------

1. A router is a layer 3 or network layer device.
2. It connects different networks together and sends data packets from one network to another.
3. A router can be used both in LANs (Local Area Networks) and WANs (Wide Area Networks).
4. It transfers data in the form of IP packets. In order to transmit data, it uses IP address mentioned in the destination field of the IP packet.
5. Routers have a routing table in it that is refreshed periodically according to the changes in the network. In order to transmit data packets, it consults the table and uses a routing protocol.
6. In order to prepare or refresh the routing table, routers share information among each other.
7. Routers provide protection against broadcast storms.
8. Routers are more expensive than other networking devices like hubs, bridges, and switches.

9. Routers are manufactured by some popular companies like −

• Cisco
• D-Link
• HP
• 3Com
• Juniper
• Nortel

Routing Table:-
A router reads its routing table to decide the best available route the packet can take to reach its destination quickly and accurately. The routing table may be of these two types −

1. Static − In a static routing table the routes are fed manually. So it is suitable only for very small networks that have maximum two to three routers.
2. Dynamic − In a dynamic routing table, the router communicates with other routers through protocols to determine which routes are free. This is suited for larger networks where manual feeding may not be feasible due to large number of routers.

• 
  

Modem:-

-------

1. Modem stands for Modulator and Demodulator. It is a device that modulates signals to encode digital information for transmission and demodulates signals to decode the transmitted information.
2. A modem transmits data in bits per second (bps).
3. The main function of the modem is to convert digital signal into analog and vice versa. Modem is a combination of two devices − modulator and demodulator. The modulator converts digital data into analog data when the data is being sent by the computer. The demodulator converts analog data signals into digital data when it is being received by the computer.
4. It is necessary for communication between digital devices and Analog devices.
5. Modem is necessary because it acts as a translator between the devices and rapidly transmits the information.
6. It converts the digital signal to Analog and vice versa to communicate between devices.
7. It encodes the signal and decodes at the other end and vice versa between the devices. 
8. Modems are useful in converting digital signals into analog signals.
9. They help in connecting the devices to the internet.
10. Only a limited number of systems can be connected to the internet through a modem.
11. Modems are prone to cyber-attacks which reduces the probability of secure transmission. 
12. The cost of a modem is dependent on the number of features it offers. More inclusion of features will lead to an increase in the cost of modem. 
13. Modems slow down when it is connected to a hub.
14. They are unable to track traffic between the LAN and the internet.
15. Modems require RJ11 Jack to communicate with telephone lines and RJ45 for connection with computers.
16. For modems to work, device drives must be installed in the operating system for configuration and communication. 
17. These devices must be configured with an Internet Service Provider (ISP) and computer for using the internet.

Bridge:-
--------

Definition: A bridge is a computer network hardware device that works at the data link layer of OSI model, and it also helps to make interconnection in between multiple networks with using of same protocol.

1. It is used for making the interconnection two LAN networks along with single and same protocol.
2. With using of MAC address, bridge gets to filter the all contents of source and destination points.
3. It helps to decrease the traffic over the network.
4. Bridge helps to hold the MAC address of all computers in the network.
6. It performs the all tasks in data link layer in OSI model.
7. Bridge helps to make connection with multiple different LANs network that has a same protocol and then they offer the communication in between the all nodes in them. 
8. Bridge are similar to repeaters and hub in that they broadcast data to every node.
9. Bridge maintain the MAC address table as soon as they discover new segment. 
10. So subsequent transmission are sent to only to the desired recipient.
11. Bridge also known as Layer 2 Switches.

Gateway:-

---------

1. It can connect the devices of two several networks having a different design.
2. It is an intelligent tool with filtering capabilities.
3. It has control over both collisions and the advertisement area.
4. It needs a full-duplex mode of connection.
5. It can make data translation and protocol conversion of the data packet according to the destination network's requires.
6. It is used to encapsulate and decapsulate the data packets.
7. It has enhanced security over any other network relating device.
8. The main disadvantage of the gateway is that gateways are slow because they need to perform intensive conversions. 

9. A device that can bridge several network structure is called a gateway. Thus gateways can link two dissimilar LANs. The major difference between gateways and routers is that routers operate at the OSI model’s network layer. In contrast, gateways operate from the lowest to the topmost layer, i.e., the application layer to the OSI model’s network layer.

Thanks & Regards

Abhishek Pathak

+91-9621134014

abhishek9621134014@outlook.com