Data link layer pdf nptel

Switch works in physical layer, hub works at datalink layer. Class 4 network topology designdelay analysis tuesday, feb 2 network topology is the arrangement of the various elements links, nodes, etc. Tcp and udp application transport network data link physical transport network data link physical. The most important functions of data link layer to satisfy the above requirements are error control and flow control. For communication to occur, two devices must be connected in some way to the same link at the same time. Lecture 3 data link layer data link control protocols. Control information can be inserted as bits depending on the information to be contained in the frame bitoriented protocol can pack more information into shorter frames.

For vi sualization purpo ses, it is simple st to imagine any link as a line drawn bet ween two point s. Lecture notes data communication networks electrical. Data link layer performs the most reliable node to node delivery of data. The control done by the data link layer is data link control. Data link layer silvia giordano ica, epfl the datalink layeris responsible for transferring a datagram across an individual link. A link is a communications pathway that transfers data from one device to another. This lesson will focus upon the functioning of the datalink layer in the seven layer osi model. Data link layer design issues providing a welldefined service interface to the network layer. Lecture 3 data link layer digital data communication techniques. The logical link control and adaptation protocol l2cap. The data link layers first sublayer is the media access control mac layer.

Data structures and algorithms nptel video lectures naveen garg, nptel video lectures, nptel online courses, youtube iit videos nptel courses. The data link and physical layer is where network abstractions are implemented. Link layer security provided at the application layer with pgp, smime, etc c four layer representation of the tcpip protocol stack see lecture 16 figure 1. Computer networks 04 data link layer total delay duration. Sdlc synchronous data link control was being employed previously. The protocols are developed in increasing complexity to help students understand the data link layer issues. Download cbse notes, neet notes, engineering notes, mba notes and a lot more from our website and app. This path, or vc, is a bidirectional logical connection across the widearea network between two end node dte devices. The data link layer is the protocol layer in a program that handles the moving of data in and out across a physical link in a network.

Data structures and algorithms nptel online videos. The mac sub layer physical layer provides binary sendreceive to data link layer 117. It forms frames from the packets that are received from network layer and gives it to physical layer. Data link layer is the second layer in osi reference model and lies above the physical layer. Computer networks by andrew s tanenbaum 4th edn pdf. Solved multiple choice questions on computer networking. Computer networking and management lesson 5 the data link layer. Link channel complexity causes the logical link and mediaaccess control sublayers split. It mainly does three controls that are its functions and their advantages. Data structures and algorithms nptel online videos, courses. Linkchannel complexity causes the logicallink and mediaaccess control sublayers split. Data link layer 6 data link layer model assume the sending host has infinite supply of messages.

This means that a defined communication exists between each pair of devices and that. The endtoend argument becomes clear at the data link layer. Network protocols cannot work with multiple layers. In this lecture, though, our focus is primarily on email security. Chapter 1 introduction to network interfaces network. Jan 30, 2015 data link layer design issues providing a welldefined service interface to the network layer. Computer networking and management lesson 5 the data. A node constructs a framefrom a single packet message. It will be useful to discuss a real datalink layer. The data link layer is layer 2 in the open systems interconnect osi model for a set of telecommunication protocols. On the sending end, ethernet or similar software organizes the data into packets of appropriate size and packages them. Oct 20, 2008 lecture series on data communication by prof. A link isthe communication channels that connect two adjacent hosts or routers. The datalink and physical layer is where network abstractions are implemented.

A dlci is used to identify this dedicated communication path between two end nodes. Data link layer this layer provides reliable transmission of a packet by using the services of the physical layer which transmits bits over the medium in an unreliable fashion. Data link layer in computer networks and its responsibilities duration. The packaging includes the physical address of the intended receiver. The mac sublayer physical layer provides binary sendreceive to datalink layer 117. Data link control in data communication iosr journals. Find materials for this course in the pages linked along the left.

At the receiving end, data link layer picks up data from hardware which are in the form of electrical signals, assembles them in a recognizable frame format, and hands over to upper layer. The mac sub layer but, different media have different constraints about multiple nodes accessing the medium 118. Data link layer and due to port a ddressing transport layer is enable to deliver data to the right process. Computer networks and internet protocol usb media storage type. Nov 05, 2012 cisco ccna 01 chapter 07 data link layer.

Data link protocols data link protocols are sets of rule and regulations used to implement data link layer. Data link layer of osi reference model studytonight. This header provides the information needed for routing e. The mac sublayer but, different media have different constraints about multiple nodes accessing the medium 118. Essentially, it is the topological structure of a network and may be depicted. The main task of the data link layer is to transform a raw transmission facility into a line that appears free of undetected transmission errors to the network layer. Frame relay provides connectionoriented data link layer communication. The three bottom layers are the physical layer, datalink layer, network layer, and are together. The data link layer provides service to the network layer above it.

Examples of linklayer protocols include ethernet, token ring, fddi, and ppp. Data link layer it is responsible for nodetonode delivery of data. It accomplishes this task by having the sender break up the input data into data frames typically a few hundred or few thousand bytes and transmit the frames sequentially. In this paper, data link control in data communication is discussed.

Cn lecture notes veer surendra sai university of technology. Layer at the sending end and what is sent up by the link layer to the ip layer at the receiving end. The data link layer s first sublayer is the media access control mac layer. The physical layer provides only a raw bitstream service between computers. Gate cs topic wise preparation notes geeksforgeeks. Jan 12, 2009 the mac sub layer data link layer provides packet sendreceive service to network layer 116. Typically, the network layer adds its own header to the packets received from the transport layer. Computer networks nptel online videos, courses iit video. This document contains the specification of the ethernet, a local area network developed jointly by digital equipment corporation, intel corporation, and xerox corporation. For communication to occur, two devices mu st be connected in some way to the same link at the same time. This page contains gate cs preparation notes tutorials on mathematics, digital logic, computer organization and architecture, programming and data structures, algorithms, theory of computation, compiler design, operating systems, database management systems dbms, and computer networks listed according to the gate cs 2020 syllabus. The data link layer provides data reliability and provides tools to establish, maintain, and release data link connections among the network nodes.

Data packets are framed and addressed by this layer, which has two sublayers. The mac sublayer datalink layer provides packet sendreceive service to network layer 116. Link access protocol balanced lapb, bit oriented protocol. Insert dle before accidental dle in data remove stuffed character at destination fig 34 8 the ohio state university raj jain bit stuffing delimit with special bit pattern bit flags stuff bits if pattern appears in data remove stuffed bits at destination fig 35. Data and computer communications mei yang based on lecture slides by william stallings lecture 3 data link layer digital data communication techniques 1 asynchronous and synchronous transmission timing problems require a mechanism to synchronize the transmitter and receiver receiver samples stream at bit intervals. The protocols used here are ip ethernet y modelo osi explain tcpip model in detail explain the 5 layer tcpip model in detail firewall y modelo osi first 3 layers osi model ftp function of layer 1 osi model h. The transport layer provides a virtual end to end message service to the higher layers. A host with a packet to send transmits it to the nearest router, either on its own lan or over a pointtopoint link to the carrier. The endtoend argument becomes clear at the datalink layer.

Tcp segment structure reliable data transfer flow control connection management 4. The network layer provides a virtual end to end packet pipe to the transport layer. The datalink layer has responsibility of transferring datagram from one node to adjacent node over a link goto top link layer and local area networks in this lesson we examine the data link layer its services, the principles underlying its operation, and a number of important data link layer protocols. The remote network layer peer should receive the identical message generated by the sender e. The layer also transmits the message packets and retransmits them if needed. The network layer is interested in getting messages to the corresponding network layer module on an adjacent machine. For communication to occur, two devices must be connected in some way to the same link at. The data link layer is used for the encoding, decoding and logical organization of data bits. The data link layer offers transmission service to the network layer. It also synchronizes the information which is to be transmitted over the data. Introduction dlc is the service provided by the data link layer of function defined in the open systems. The ethernet a local area network data link layer and physical layer specifications digital equipment corporation intel corporation xerox corporation maynard, ma santa clara, ca stamford, ct version 2. Data link layer is responsible for converting data stream to signals bit by bit and to send that over the underlying hardware.

Pal, department of computer science engineering,iit kharagpur. The datalink layer offers transmission service to the network layer. Data networks lecture 1 introduction mit opencourseware. Primary controls operation of link secondary under control of primary station combined issues commands and responses link configurations unbalanced 1 primary, multiple secondary balanced 2 combined stations. In osi reference model terminology the tcpip protocol suite covers the network and transport layers. Breaking input data into frames typically a few hundred bytes and caring about the frame boundaries and the size of each frame. Framing in data link layer iit lecture series computer networks. Frame relay is a connectionoriented service, operating at the data link layer layer 2 of the osi model. The data link layer, also sometimes just called the link layer, is where many wired and wireless local area networking lan technologies primarily function.

For visualization purposes, it is simplest to imagine any link as a line drawn between two points. Link layer and local area networks in this chapter we examine the data link layerits services, the principles underlying its operation, and a number of important data link layer protocols. We learn that the basic service of the data link layer is to move a networklayer datagram from one node host or router to an adjacent node. Lecture 3 data link layer digital data communication. Defines the methods and provides addressing information for communication between network devices. The ethernet a local area network, data link layer and. This lesson will focus upon the standard of the datalink layer in the seven layer osi. Invented 1970 by ibm for sdlc synchronous data link protocol eytan modiano slide 9 1 1 1 1 1 1 0 1 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 1 0.

Discuss the services provided to the transport layer by the network layer. Regulating the flow of data so that slow receivers are not swamped by fast senders 4 for this, the data link layer takes the packets it gets from the network layer and encapsulates them into frames for transmission. Data link layer layer 2 page 1 of 2 the secondlowest layer layer 2 in the osi reference model stack is the data link layer, often abbreviated dll though that abbreviation has other meanings as well in the computer world. Analog and digital, analog signals, digital signals, analog versus digital, data rate limits, transmission impairment, more about signals. Used to multiplex multiple logical connections between two devices.