Referring responsibility of data link layer and is

    Referring to distributed computer architecture, you are to write an assignment on “The Data Link Layer and Physical Layer”, and in particular, how it addresses the following questions. 1. Does the link layer encapsulates the datagram received from the network layer into a frame?Data link layer is the second layer which locates between physical layer and network layer, when a data message transmits to outside, usually, it will go through multiple layers and each layer will encapsulate the data into a bigger datagram, data link layer will encode the bits into packets before it transmitted to the physical layer. 2. Is the link layer incapable of detecting an error in a received frame?Link layer can not only encode the message from the network layer but also be able to do the logical link control and flow control which can detect an error and recover when the error happened in transmission. When sender side sends a message, it adds a flag to the datagram to represent error detection code. Once the message obtained by the receiver, it will recalculate the datagram to get an error detection code, this error detection code has to be same as the error code sent from the sender. For example, when the sender sends the message, the sender uses an algorithm to generate the error detection code based on the message bits, any changes to the message will cause the error detection code becomes different. The receiver side will use the same algorithm to calculate the error detection code to make sure these two error detection codes are same.3. Is flow control one of the services provided by the link layer?Yes, it is. Flow control is one responsibility of data link layer and is also a very important part of data link layer. The functionality of flow control is managing the amount of data which can be sent from a sender before receiving acknowledgment. The reason is the receiver side has the speed and memory limitation of processing the data received from the outside, for example, when school opens the class registration server access, the first day, students usually experience the slow loading of the website, the reason mostly is because the server is processing the huge amount of request from all students. The receiver will inform the sender before the limitation happened, and allow fewer data to be sent before the limits reached. 4. What operations does the link layer support?The data link layer supports the datagram processing between the network layer and physic layer, which includes encapsulating the datagram from bits to packet before it transmitting to outside, and decode the datagram from the encapsulated packet back to bits when receiver side received the data packet. It also contains the operations for logical link control which is to control the amount of data sending, hardware addressing which is to obtain the MAC address when it transmits data frame to the destination, media access control which is mainly to avoid and recover from congestion and collusions, error detection which is to verify the data message during communication, handling and defining physical layer standards. All these operations supported by link layer is to make sure the data the reliable when it sends out to destination or received the data from outside. 5. A brief description of the IEEE (Institute of Electrical and Electronics Engineers)802 standard development.The IEEE 802 committee was formed in February 1980 and its mission is to set standards for LANs and MANs. The services and protocols defined in IEEE 802 are limited to the lowest two layers of the OSI model In fact, the IEEE 802 divides the OSI data link layer into two sub-layers: Logical Link Control (LLC) and Media Access Control (MAC). The IEEE 802 series of standards are local area network and metropolitan area network standards developed by the IEEE 802 LAN / MAN Standards Committee. One of the most widely used are Ethernet, Token Ring, Bridging, Virtual Bridged LANs, Wireless LAN and more. Each of these series of standards is covered by a dedicated working group within the committee. With the development of internet technology, there are a lot of new communication technology brought into the market and some environment got changed meanwhile, there is a need to provide a standard for those new communication. IEEE 802 has been developed 25 working groups at present, each working group is to provide the standard in specific communication environment. For example, IEEE 802.1 is the standard for higher layer LAN protocols. IEEE 802.3 is the standard for Ethernet. IEEE 802.24 is the new one which was introduced in 2012 for smart Grid Tag. 6. A brief description of WiFi (Wireless Fidelity).Wi-Fi (Wireless Fidelity)is a wireless network communication technology which provides the functionality to connect the electronic devices to a wireless local area network (WLAN). Usually it uses 2.4G UHF or 5G SHF ISM radio frequency. Wi-Fi wireless connection has distance limitation which allows the device in specific the range to connect to the wi-fi network. The father the wifi brand spread out, the weak the strength of the signal. Also, to connect to a wireless LAN can be password protected, or authentication protected, or public opened. The communication protocol is based on the IEEE 802.11 series protocol standard. The category of wireless network in wireless local area network (LAN) refers to the “wireless compatibility certification” is essentially a commercial certification, at the same time is also a kind of wireless network technology, computer via Ethernet cable connection before, while the wi-fi is connected by radio waves; In common is a wireless router, then cover the range of the wireless router waves can be connected to the Internet using wi-fi connection, if connected to a wireless router ADSL line or other Internet access routes, also known as hot spots7. A brief description of the link layer sub-layers.8. A brief description of NICs (Network Interface Cards).9. Types of data link protocols.10. MAC (Media Access Control) design and CRC (Cyclic Redundancy Check) error detection scheme.The assignment is between 15 to 20 pages and should be written in accordance with the specifications given by the instructor, APA style (see www.apa.org).Notes on Assignment 1 WritingAll assignments will be carefully looked at and appropriate marks are given.These marks are given in the following fashion;1.    How close is the written assignment to the actual theme of the given assignment title?2.    How well the idea(s) are presented in the assignment.3.    The amount of plagiarism, do not exceed 15%.The marks are spread out in accordance with the above rubrics.You should include figures in your discussion. And when you do, these should be labeled and referred to in your discussion correctly, not leaving things for the reader to figure out what’s what.Also, always check your text for writing mistakes and never refer to a URL inside your text, URL placement is in the references at the end of your assignment.

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