v Router
Introduction
From the view point of networking, Routers is more intelligent, sensitive protocol linking small device which is especially used to link separate network and provide access of internet to the users. Similarly, Due to its capability of working at the layer 3 of OSI Layer it is more complicated than any other exiting networking devices. Specially routers can be a hardware, software or both which can connect two different networks such as (a) Ethernet to Ethernet , (b) token ring to Ethernet, (c) MAN to WAN. As a result, the routers are similar to bridge and networking HUB but in fact there is incomparable difference between them and routers are more function able.
Advantages:
We know routers works at the third layer of OSI Model it is basically used for communication which include the internet. Likewise, Routers find the shortest and the easiest path to transfer the data, information between the different sending and receiving computers without any disturbance. During the addressing of the data routers uses the IP Addressing for accessing and also for forwarding the data in the one hand. On the other hand, routers manage or provide the alternative solution for the broadcast problems as it break the networks into many broadcast domain. Similarly, without using MAC address it implement quality of service using traffic shaping, protecting traffic by using encryption and filtering the traffic by Access Control List.
Disadvantages:
Leaving the advantages of the routers there we can find some disadvantages also. Typically in case of performance speed, system cost, and working protocol. In case of static routing the users of the networks administrator must update the routing table manually but this is automatically update during the data transfer process between different computers in dynamic routing. Similarly as compare to the price of the routers it is more expensive than other networking devices. Basically the performance speed is quite slow than that of bridge because of its complex calculation in network layer. Finally its works with some specific protocols like TCP/IP, DECnet, OSI, XNS, IPX/SPX etc.
Function: Some of the function of routers is listed below:
ü Removal of corrupt packets or data
ü Interconnection between different networks architectures, physical media etc.
ü Provide a suitable path for packets transfer
ü Performs complex mathematical calculations
Conclusion:
Apart from the advantage and disadvantage of the routers we came to the conclusion that it is able to reduce the traffic in the network by avoiding corrupt data & transferring data to the destination through the suitable path.
v Gateway
Introduction:
A networking device which is used to link the different LANs. It can perform the overall function of bridge & routers and also capable to converts the entire protocol of different networks. On the other hand gateway operates at all the seven layer of OSI model. Hence, it is good protocol converter.
Reasons and Advantages:
Unlike the routers that performs at the network layer of the OSI model which is able to accepts, relays & transfers of packets only under the network using the same protocol. But a normal gateway is able to convert a packet designed for one protocol to different existing protocol e.g. in case of connection of Token ring with Ethernet, the gateway also converts the Token ring protocol to Ethernet protocol. It works as a server for other server because it can understand the protocol used by each of the network link into the routers & able to translate it into others protocol.
Disadvantages:
Generally a normal gateway used in the connection between the dissimilar LANs is software installed on a router. Therefore, it is very much expensive in cost as similar as router. As a gateway is a pre-installed software programmer in a router it is more difficult to network user to install it or configure it without any knowledge. Due to the complex conversion process & greater requirement a gateway is slower than other devices such as bridge & routers.
Function:
As moving deeply in the complex function that the gateway performs is task dedication. Gateway is completely dedicated to the specific task at once & contributes to complete the task very well. And the another function that a gateway play is the interconnection between the completely different system together. Likewise, the main & important function of the gateway is protocol conversion. i.e. a gateway can control the entire protocol of a network to other.
Conclusion:
Gateway is an internetworking device but it can perform the whole function which is performed by the interworking bridge and routers. Gateway works on the seven different layer of OSI model & are often used as server-side portals through network firewalls & also used as the translators for access to the resources stored on http system. Hence, protocol conversion is the wise part which is particularly handled by gateway.
v Switch:
Introduction:
The foundation of the communication link between the two different nodes is noticed as switching. And the device which is used is known as switching & the system is called switching system. The work at the data link layer of OSI model. Typically, the switches are made to solve the problems regarding the bandwidth & collision in the networks. With the help of ASICs they make their switching decision in hardware.
Reasons and Function:
During the process of switching the frame in hardware, the switch may utilize multiple methods of switching which supports half-duplex or full-duplex connection with hundreds of ports. The main function is to switch the frame very fast. Here, switch learns MAC address statically or dynamically in CAM table & forward the frame very intelligently without high traffic. Similarly we can configure different ports of different speed at the switch.
Advantages:
Besides solving the collision & the bandwidth problems switch is able to perform the full-duplex at all the ports & established the dedicated connection within a routers, PC or the server. Similarly a switch can frame very fast up to the speed of 50,000 per second where we can create a dedication for special ports i.e., simultaneous or multiple session transmission between the ports.
Disadvantages:
As we already know switch play a vital switching role in the hardware with the help of application specific integrated circuits(ASICs) which is a very especial processor designed to perform a very few specific task. Hence ASICs are very expensive or costly as compare to the normal processor. The cut-through switching is only usable if the vendor has included it in its switching product. If the vendor is without dynamic switching there may be the problems switching the bad frame. Since the header could readable but remaining frame are corrupted due to collision. Hence dynamic switching reduces the problems of switching the bad frame.
Conclusion:
Finally, switch is similar to bridge but in facts there is a huge difference between them. Generally switch switches the frame very fast & tries to control the problems of collision & bandwidth. Hence by implementing the entire three methods (cut-through, fragment-free & store and forward) switch is able to switch the frame at a rate of 50,000 & more per seconds.
v Bridge:
Introduction:
Bridge is a networking device which normally works in the physical and data link layer of OSI model. It is capable of connecting two network segments and transferring data between them by using the same protocol. Bridge can also be used as connecting device between the different HUBs that is to say it is capable of connecting different HUB.
Reasons:
Especially bridge is a store & forward device. During the connection of different LANs it receives the frame from one LAN and transfer the same frame without encapsulating or without modification to other LAN. By using local and remote bridge a network administrator can easily extend the network distance i.e. local bridge link the LAN separated by small distance whereas remote bridge link the LAN separated by large distance.
Advantages:
As bridge can work in the data link layer it must be capable of handling physical addressing. As compare to broadcasting HUB it is more intelligent because bridge maintain the physical address tables and transfer the data with the help of receiving and sending computers MAC address. During this process it reduces the unnecessary traffic problems by controlling broadcasting. Similarly by implementing remote bridge network distance can be extended because remote bridge link the different LAN separated by large space. Meanwhile a normal bridge can connect different media within the same network whereas a translation bridge can link the different architecture of the networks.
Disadvantages:
Leaving the advantage of the bridge some sort of disadvantage can be found on the bridge. The speed is slower than the repeaters but it is fast than that of the routers. Likewise comparing the cost it is expansive than repeaters but a bit cheaper than the routers. And the main disadvantage is that it is not able to handle the multiple paths.
Functions:
Apart from the learning, forwarding and removing loop function of bridge there are some more function listed below
ü Solve the problems of collision and bandwidth.
ü Able to connect different media with the networks.
ü Network traffic reduction.
ü Use MAC table during the data transmission.
ü Can link two similar networks together.
Conclusion:
Among the four different types of bridge translation can link (Ethernet to Token ring) different architecture together. Hence in the data link layer bridge can access to information because of the physical address of both source and destination computer. Finally it decides whether to forward data or not to forward it.
v Repeaters:
Introduction:
Another mostly used network connecting device is repeater. In the OSI layer, repeater work at the first physical layer. It is a low-level device of transparent nature it cannot distinguish between the data and noise. When there is noise in the process of communication it amplifies with the data. So repeater is a signal amplifier used to amplify the low signal to high signals.
Advantages:
At the physical layer where the repeaters allow the users to extend the physical length of networks. That is to say repeaters expand the network over the large distance by using remote repeaters. Also a repeater can link the various Ethernet segments of any media type and it is capable of amplifying the signals before the signals became weak.
Disadvantages:
Working in the physical layer they are not able to known the type of data transferring, different
Address and protocol used so they are called unintelligent electronic device that cannot filter and
Translate the information or message. Next the location of repeaters also plays a huge role because
Noise can alter the data and initial data becomes unrecoverable. But the number of repeaters used
Must be least in order to avoid the propagation delay. Hence network architectures maintain the
Limited repeaters in their network. And the other disadvantage of repeaters is that it cannot connect
The network of two different architecture such as Token ring and Ethernet etc.
Functions: The major function of repeaters is as listed below:
ü It amplifies the signals without impacting the speed of the networks.
ü Network administrator can expand the network into large distance with the help of repeater.
ü Concerning the location of repeaters used the signals can be refreshed back without any noise and delay.
Conclusion:
Finally, repeaters are an unintelligent connecting device which operates in the physical layer and contribute to amplifying the data before the signals became weak and noisy.
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