Telecommunication
Advantages and disadvantages of packet switched networks over circuit switched networks
These two types of switched networks are both used in various transmissions of data from one end to another. A circuit switched network is a virtual connection that connects two ends and has a bandwidth, while a packet switched network is where packets of information is send from the source to the destination through any suitable connection available. Both two types of switched networks have advantages as well as disadvantages
One advantage of the packet switching network is that it utilizes the available networks because of its capability to distribute the available traffic through various connections available. This makes it much effective than circuit when sending huge amount of information. Furthermore, packet switching has much higher flat tolerance compared to the circuit network because bad performance is enhanced by the available network as well as capability of putting in sequence of the incoming packets by the involvement or assistance of the extra overhead. On the other hand, packet switching network has some disadvantages, which includes the need to resent some of the packets that may get lost in their transmission. This may cause delay in the transmission of data packets. This is best explained by Time-to-Live for packets concept. This concept means that after the packets expires or time is out, they are dropped to the next devices, which receives them and sends them to the end. This explains why this network might delay sending of information. Furthermore, some packets may not be transmitted to the end as some are dropped on their way hence may reach the destination in bad sequence.
Some of the disadvantages of circuit switched network are that messages are end quickly in wholesome as opposed to sending through paths. The message send arrives as a whole and therefore there is no need of reassembling the message hence ensures that communication is fully enhanced.
Suppose transmission channels become virtually error-free. Is the data link layer still need?
This data link layer provides/ensures that there is error free transfer of frames from two computers over the application layer. Layers that are above data link layers are able to assume virtually free transmission over the network but those below this are not able. It is therefore an important layer if reliable delivery of data is required. Even though there are many routable protocols such as internet protocol and TCP, they are not able to provide and utilize the services of data-link layer delivery services. Therefore, for reliable transmission of data this layer is of importance since for data to be transmitted well it must be provided by protocol operating at the transport layer. Furthermore, data link layer provides a range of services in the transmission of data. These includes it terminates and establishes logical links; it controls frames transported between computers and can allow or restrict transmission of frame buffers. It ensures transmission and reception of frames sequentially, listens and provides frame acknowledgement by identifying errors in the physical layer. It also manages media by checking whether the computer is allowed to use physical media, it delimits and creates frame boundaries and checks frames for errors as well as inspection of the addresses of each received frame and sending it to its required layer. Therefore, it is paramount that these data link layer is still needed even if the transmission channel becomes virtually error free.
Mr. Not To Bright decides to do away with DNS. Instead, he stores the mapping between domain names and IP addresses in a local file that is stored on his computer. He argues that this approach is better since it resolves domain names much faster. What is the problem with this approach?
The approach that Mr. Not to Bright has chosen is not appropriate. This is because; it will be difficult for him to remember the sites that he wants to browse. It is also time consuming and may not be able to locate the address easily. Second is that he would not be able to update the addresses and therefore will not be able to find new domains. Their names or IP connections will not be available to him because, he is not the one who creates them. The reasons why this approach he has chosen is bad is because every computer has its IP address. This address comes from DNS, which consists of series of servers that translates IP addresses to information that is easily recognized by human beings. For instance, a domain name of Yahoo maybe 216.109.112.135. This is a difficult code to remember and to type into the browser. Therefore, DNS allows people to use links such as www.yahoo.com to access easily to yahoo. This therefore saves time and agony of remembering four-digit code number. Therefore, use of DNS helps to direct users to internet service providers that help them to find the server and locate information easier, hence the reason why he should not use this approach.
What protocol (between UDP and TCP) do the following protocols use? Give reasons accordingly.
FTP, HTTP and DNS
TCP is a connection-oriented kind of protocol that transmits data. This protocol requires that data is consistent at the source. On the other hand, UDP also called User Datagram Protocol in less of connection protocol. It does not require data to be consistent like the TCP and does not need connection to be available between the host computers for consistency of data. It has smaller data packets not more than 512 bytes. It communicates with each other and it transfers information in form of queries because of its being not able to connect. TCP on the other hand is used in transmission of data between secondary and primary DNS. This is because it is able to transmit information between different servers.
FTP also called file transfer protocol, is a network protocol that is used in transferring of files from one computer to another. Therefore, this transfer is necessitated by TCP such as the internet. UDP is not conducive for this. TCP protocol is able to send huge files and over a distance. Furthermore, TCP is able to send encrypted files over the internet hence appropriates. It is also appropriate protocol to send FTP files because; these files can be edited and changed by the receiver.
HTTP also called hypertext transfer protocol is an application layer protocol that is designed in the framework of an internet protocol suite. It operates as a request –response protocol in a client-computing model. It communicates over TCP connections. Even though it may be used on UDP like Simple Service Discovery Protocol, it is however effective when used under TCP. The reason is because HTTP is used to transmit data over the internet and is built of the internet protocol suite.
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