TYPES OF COMPUTER NETWORK DEVICES
The devices which are employed for interaction between various hardware applied in the computer network are called network devices. There are various types of electronic devices practiced in networking which are identified as network devices/network equipment. In a computer network, network devices are essentially used for conveying and collecting the data quickly and securely in between computers, printers, fax machines, etc.
Some of these devices can be connected to the internetwork and some can be part of the network. These devices are particularly designed to handle digital or electrical connections to perform their roles efficiently. This article brings to you detailed information on Network Devices including hub, switch, bridge, routers, and more.
Know more about Internet, here.
Network Devices
HUB
Hub is considered as one of the basic icons of networking devices which is implemented at the physical layer and hence connects networking nodes physically together. Hubs are fundamentally utilized in networks that use twisted-pair cabling to connect nodes.
They are created in a way to send the packets to the other appended devices without editing any of the transmitted packets received. They work as pathways to direct electrical signals to travel along. They transmit the information without caring of fact that the data packet is destined for the device linked or not.
Hub falls into two categories
Active Hub
They are more advanced than the passive hubs. They not only facilitate the path for the data signals, but they also regenerate, concentrate and strengthen the signals before transmitting them to their destinations. Active hubs are also called ‘repeaters’.
Passive Hub
They are similar to the point contact for the wires to build in the physical network. They have no work of modifying the signals.
Ethernet Hubs
It is a device linking various Ethernet devices together and makes them carry on the functions as a single device. They are different in speed in terms of data transfer rate. Ethernet utilizes the so-called Carrier Sense Multiple Access with Collision Detect (CSMA/CD) to control Media access. The Ethernet hub connects in a “half-duplex” mode where the possibility of data collision is inevitable most of the time.
Switches
A switch does so by having in-built learning of the MAC address of the devices linked to it. Since the sending of data signals is predefined in a switch, therefore the network performance is consequently effective. Switches work in a “full-duplex” mode where nodes can send and receive data from the switch simultaneously unlike in half-duplex mode.
The transmission bandwidth in switches is double as compared to the Ethernet hub transferring around 20Mbps connection into 30Mbps and around 200Mbps connection to become 300Mbps. Performance enhancements are observed in networking with the extensive utilization of switches in recent days.
The given method will elucidate further how data transmission takes place via switches:
- Cut-through transmission: It enables the packets to be transmitted as soon as they are received. The technique is prompt and quick but the facility of error checking gets overlooked in these kinds of packet data transmission.
- Store and forward: In this switching technique the entire packet is taken and ‘checked’ before being transmitted further. The errors are thus eliminated before being propagated further. The drawback of this process is that error checking spends a relatively long time consequently resulting in a bit slower processing and delivery.
- Fragment Free: In a fragment-free switching environment, a greater part of the packet is examined so that the switch can identify whether the packet has been caught up in a collision. After the collision status is identified, the packet is forwarded.
Bridges
A bridge is a type of computer networking component that builds the connection with the other bridge networks that are present on the same protocol. It is implemented at the Data Link Layer of the OSI Model and links the different networks together and creates communication between them. It combines two local-area networks; two physical LANs into bigger logical LANs or two segments of the already existing LAN that use the same protocol.
Apart from creating larger networks, bridges are also utilized to segment bigger networks into smaller portions. The bridge performs this by placing itself between the two portions of two physical networks and managing the flow of the data between them.
Types of Bridges
There are three types in which bridges can be segmented:
- Transparent Bridge: As the name implies, it resembles being transparent for the other devices on the network. The other devices are ignorant of their existence. It only restricts or permits the data according to the MAC address.
- Source Route Bridge: It received its name from the fact that the way which packet takes via the network is implanted within the packet. It is mainly utilized in Token ring networks.
- Translational Bridge: The process of conversion happens via Translational Bridge. It transforms the data format of one network to another. For example, conversion of Token rings to Ethernet and vice versa.
Switches Superseding Bridges
Ethernet switches are gaining trend consecutively as compared to bridges. They are progressing in terms of logical divisions and segments in the networking area. Switches are being referred to as multiport bridges because of their high-level functionality.
Routers
Routers are network layer components and are particularly categorized as Layer- 3 components of the OSI Model. They work on logical addressing information in the Network header of a packet like IP Addresses.
A router is utilized to implement bigger complex networks by complex traffic routing. It has the authority to connect dissimilar LANs on the same protocol. It also has the authority to restrict the flow of broadcasts. A router mainly comprises a hardware component or a system of the computer which has multiple network interfaces and routing software.
Functionality
When a router receives the data, it analyses the destination address by checking the header of the packet. Once the address is analyzed, it finds in its routing table to know how to connect to the destination and then transmits the packet to the higher hop on the route. The hop might be the last destination or another router.
Routing tables play a very crucial role in enabling the router to make a decision. That is why a routing table needs to be updated and complete. The two methods using which a router can receive data are:
- Static Routing: In static routing, the routing information is fed into the routing tables manually. It is not only a time-taking task but gets prone to mistakes as well. Manual updating is also required in the case of statically configured routers when a change in the topology of the network or the format takes place. Thus static routing is considered for the smallest environments with the least number of routers.
- Dynamic Routing: For a larger environment dynamic routing proves to be the practical solution. The process includes the use of peculiar routing protocols to establish communication. The purpose of these protocols is to facilitate the routers to transmit information to other routers so that the other routers can build their routing tables.
Brouters
Brouters are the collaboration of bridges and routers. They take up the functionality of both networking components working as a bridge when forwarding data between networks and serving as a router when routing information to individual systems. Brouter works as a filter that permits some data into the local network and redirects unknown packets to the other network.
These days Brouters are not used because their functionality is embedded into the routers to work as bridges as well.
Gateways
It facilitates computer programs, either on the same device or on a different device to share information across the network via protocols. A router is also a kind of gateway because it interprets data from one network protocol to another.
Other components such as a bridge translate the data into different forms among two networking systems. Then a software application transforms the data from one format into another. Gateway is a crucial tool to translate the data format, even though the data itself remains unchanged. Gateway might be implemented in some other device to add its functionality into another.
Network Card
Network cards are sometimes referred to as Network Interface Cards (NICs). These are hardware components that link a computer with the network. They are installed on the motherboard. They work to develop a physical connection of the network to the computer. Computer data is transformed into electrical (analog) signals sent to the network via Network Interface Cards.
They are also able to manage some important data-transformation functions. These days’ network cards are software controlled unlike in older days when drivers were required to configure them.
Modems
A modem is a device that transforms computer-generated digital signals into analog signals to enable their traveling through phone lines. The ‘modulator-demodulator or modem may work as a dial-up for LAN or connect to an ISP.
Modems can be both external, as in the device which correlates to the USB or the serial port of a computer, or proprietary elements for handheld smart appliances and other devices, and as internal, in the form of add-on expansion cards for computer systems and PCMCIA cards for laptop computers.
The design of a modem varies for both the external and internal modem. In internal modems, IRQ – Interrupt request is utilized to configure the modem in addition to I/O, which is a memory address. Usually, before the installation of the built-in modem, integrated serial interfaces are disabled, assigning them the COM2 resources at the same time.
For external types of modem, the modem assigns and uses the resources itself. This is especially helpful for the USB port and laptop users as the non-complex and simpler nature of the process renders it far much more useful for daily usage.
The modem working efficiency and processing is decided by two factors:
- Speed of UART –An acronym for Universal Asynchronous Receiver or Transmitter chip (installed on the motherboard to which the modem connection is established)
- Speed of the modem itself.
RJ45 Connector
Devices in a wired network are ordinarily connected physically to a server, router, modem, or each other with Ethernet cables. The individual end of an Ethernet cable has a connector named an RJ45 connector.
RJ45 is a kind of connector generally applied for Ethernet networking. It resembles a telephone jack but is somewhat wider. As Ethernet cables have an RJ45 connector on each terminal, Ethernet cables, therefore, are identified as RJ45 cables. The “RJ” in RJ45 stands for “registered jack,” as it is a standardized networking interface.
Firewall
A firewall is a network protection device that controls incoming and outgoing network traffic and determines whether to allow or block specific traffic based on a determined set of security rules. A firewall can be hardware, software, or both. A firewall builds a boundary between secured internal networks and outside untrusted networks, such as the Internet.
Types of firewalls
- Proxy firewall
- Stateful inspection firewall
- Unified threat management (UTM) firewall
- Next-generation firewall (NGFW)
- threat-focused NGFW
Which Device Works on Which Layer
- HUB works in the physical layer(Layer 1) of the OSI model.
- Switches operate in the data link(Layer 2) layer of the OSI model.
- Bridge operates at the data link layer of the OSI model.
- The router is essentially a Network Layer device.
- Gateways operate at the network layer of the OSI model.
- Brouter can work either at the data link layer or a network layer.
- NIC card works on both the physical and data link layer of the OSI model.
- The firewall operates on the network layer of the OSI model.
- RJ45 works on the Physical Layer of the OSI model.
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