Networking devices Explained (System fundamnetals)

Networking Devices

Network devices are devices that are used to setup, manage and secure the networking environment. They are the devices that makes it possible for humans to send and receive messages or data across the digital world. Below are the list of the basic networking devices.

• Hub
• Repeater
• Bridge
• Switch
• Access Point
• Firewall
• Router

Hub

This network device is the most simple and most commonly used network device. It is used to connect devices together, in other to send and receive data. Hub is a layer 1 (Physical layer) device. Hub doesn't filter traffic nor maintain any table. To make work easier for Hub, when it receives packet it send it to all active devices that are connected to it. The devices will collect the data check the credentials (address) if it matches its own it keep it and when it doesn't match its credentials it discard it respectively. This network device is sometimes call Non-intelligent switch. Yeah non intelligent because all it knows is sending out any packet that comes to it without filtering who is suppose to get it. Hubs are cheap and easy to set up. But they comes with many disadvantages. Hub it self is one collision domain. Meaning it has only one path to send and receive data. Take for example: computer A is sending data and computer B decided to send data too. What do U think will happen since they only follow one path! Definitely they will collide! When they collide all the ports receives a gaggle message or in another term a destroyed and useless message and the packets will never reach its destination. A hub can another be seen as a road without traffic! Think of what will happen on the road if no traffic light or traffic warden exist. There always will be accident right? That is what always happens on the Hub since there is no control. Hub comes with many ports which devices can connected through it. Collision occurrence causes traffic which slows down the network.

Repeater

This sometimes called an amplifier. I know you are familiar with what an amplifier does, it regenerate signal so as to cover a long distance. An Ethernet only covers 100 meters but with repeaters at every end it can go far. The work of repeater is just to repeat the signal to avoid downgrading before reaching its destination.

Bridge

A bridge is networking device which is capable of helping LANs to to interconnect. As the name already gave the reader a clue, bridge does exactly what normal bridge does i.e. linking two things or roads together. Bridge has the capability of forwarding data to its destination. Unlike hub it knows where to forward the data, because it maintains a table which it keeps all the MAC addresses of all the devices connected to it.

Example of Bridge Table

Interface A	MAC Address
Interface B	MAC Address
Interface C	MAC Address
Interface D	MAC Address

For example when two different departments wants to send and receives data simultaneously bridge can help. Switches limits the number of collision domains too. Lets say department A and B LAN uses two Hubs one in each departments. When connected together the collision domain remains the same one! But when a bridge is introduced into the network they will be two different collision domains. Computers in department A can only got its collision within its domain same with department B, thus helping the network to be a bit efficient. Bridge is a layer 2 (Data-link layer) device. Each port in bridge is a different collision domain. In other words each port is equivalent a hub. A bridge is a broadcast domain. Which means it has the capability to send unicast messages and broadcast respectively.

Switch

A switch is a bridge with additional features. The additional features of switch to bridge are as follows:

• Switches are faster than bridges
• Switches has more ports than Bridges
• It operates on full duplex mode.
• It checks the packet for error
• It supports Broadcast domain per VLAN

Access Point

Access point is a device which allows devices to connect to the network wirelessly. This device has a wired or wireless connection with the networks, thus helping devices to be present in to the wired networks. Access point uses WIFI, WiMax or other related standard. Good example of APN is what people often called a router, which is issued to them by telecoms companies or ISP (internet service providers) to have access to the internet. The device serves as an interface between the ISP and the end user.

Firewall

This is a network security device which filters traffic based on the rules set. A firewall makes sure traffics blocked doesn't have access to the network and traffic that is not meant to go out are restricted respectively. Some organization do restrict staffs to certain sites especially social networking sites, while some countries do restrict certain sites like porn from entering into their country. Firewall can be a software, windows machine do comes with firewall already installed, while some proprietary antivirus do offer firewall services.

Router

This can be seen as the heart of the network. Router connects different networks together to share resources. Routers are highly intelligent impact its the most intelligent in all the network devices. Router can be seen as a computer too, because it carries out computing jobs. They are sometimes called layer 3 (Network layer) switches. Router is responsible for packet forwarding which makes it very paramount in internetworking. Without router there is definitely no internet. Internet is all about linking different networks (ISPs) together with the purpose of exchanging data. As already discussed in the introduction OSI reference model, layer 3 deals with logical addressing (IP internet protocol). When packet arrive the router it de-encapsulate it and check for the network portion of the IP address, then checked its routing table then re-encapsulate it back without altering the data and send the data to the network or the best path to reach the network. Each port in router stands as a single broadcast domain. This is one of the reason that routers doesn't forward broadcast messages. Router maintains a table called routing table. Unlike the switch and bridge, routing table doesn't only contains network address and interface, it also include how the devices are been connected. Below is an example of routing table.

Network destination	Netmask	Gateway	Interface	Metric
This defines the destination network address.	The subnet mask of the Network goes here.	The gateway address goes here. This is the address of the next router on the path to the destination.	The router interface to reach to the destination is here.	This is the distance to reach to the destination. The better (less) the metric the best the path.

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