This note is an introduction to the design and analysis of computer networks and their applications, including the basics of data communication, network topologies, protocols, routing and switching, naming and addressing. The data link layer provides service to the network layer above it. Protocol data unit pdu is a term to define any one of the following. Sdlc protocol or the synchronous data link control was first developed by ibm. Ip addressing as with any other network layer protocol, the. The osi model open system interconnection model defines a computer networking framework to implement protocols in seven layers. Data communication and computer network 2 all devices connected together with a single device, creating starlike structure. The logical link control llc is an interface to the media access control mac layer.
The remote network layer peer should receive the identical message generated by the sender e. Needed when ip datagram size link layer mtu ipv4 performed by the router meeting the problem ipv6 performed by the source router only. Pdf data link layer is the protocol layer which transfers data. At the top, we have the logical link control llc layer, which is the one communicating with the cpu, while at the bottom we have the media access control mac layer, the one putting signals on the cable and reading them from it. Then add the segments and use the sum as redundant bits. Handle transmission errors error control noisy links becomes error free as. Verification of protocols using finite state machine. All devices connected arbitrarily using all previous ways to connect each other. Introduction to internetworking 17 characteristics of the osi layers layer 7application layer layer 6presentation layer layer 5session layer layer 4transport layer layer 3network layer layer 2 data link layer layer 1physical layer figure 12 illustrates the seven layer osi reference model. To intermediate the communication between the media and the cpu, the data link layer is divided into two sub layers.
A protocol in the networking terms is a kind of negotiation and rule in between two networking entities. They are slower than synchronous protocols in transmitting data. Osi model data communication and networking notes in pdf. In this system all the functions in a network can be defined and slotted into layers. Osi model is a set of protocols that allows any two system to communication regardless of architecture. Data link protocols can be broadly divided into two categories, depending on whether the transmission channel is noiseless or noisy. It contains multiple choice questions and answers about physical layer, data link layer etc. Tcpip is normally considered to be a 4 layer system. The actual protocols encompassed in the link layer are numerous, and the implementation details can be found in various documents throughout the internet and in trade texts. This layer is also responsible for logical mac addressing and llc processing, creating logical topologies, and controlling media access. The main principle is to divide the data into segments of n bits. Data link layer data link layer protocols create, transmit, and receive packets.
This header provides the information needed for routing e. Reliable data transfer service between two peer network layers. Introduction to computer networks course notes download book. The lowest layer is physical layer and the highest one is known as the application layer.
Data link layer, layer 2 in the tcpipbased layered network, layer 2 is the data link layer. Data link layer it is responsible for nodetonode delivery of data. Each layer usually has more than one protocol options to carry out the responsibility that the layer adheres to. Mcq questions and answers on data communication and computer networks or multiple choice questions with answers on data communication and networks from chapter communication network fundamentals. Computer networks hand written notes download student. The fields in the ppp header and trailer include the. This packaging process is referred to as framing or encapsulation. Pdf implementation of data link control protocols in wired network. This is the seven layer or level in a complete communication system. Data communication and computer networks pdf notes dccn. The transmission over layer 1 is not necessarily free of errors. The llc sublayer is responsible for reliable transfer of frames between two directly connected entities. Typically, the network layer adds its own header to the packets received from the transport layer.
The simplex protocol is hypothetical protocol designed for unidirectional data transmission over an ideal channel, i. These quiz objective questions are helpful for examinations nielit, bca, b. In connectionless data transfer, data are transferred from one entity to another. Pdf a study on different attacks on transport, network. Data networks lecture 1 introduction free online course. 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.
Networking osi model data link layer fundamental concepts duration. The data link layer is also called as the layer 2 of the osi model. View data link layer ppts online, safely and virus free. The fields in the ppp header and trailer include the following. The protocols are developed in increasing complexity to help students. Ip defines the address thats unique to each computer\n4. Datalink layer protocols that are reliant on a specific physical layer may be limited to the transmission medium involved, but, in some cases e. We will exam how various data link layer protocols deal with these issues. Synchronous protocol characteroriented user data is a sequence of delimited characters bitoriented user data is encapsulated by frames.
The remote network layer peer should receive the identical message generated by. Osi model 7 layers explained pdf layers functions what is osi model. Download cbse notes, neet notes, engineering notes, mba notes and a lot more from our website and app. Go back and selective repeat arqs, performance and efficiency. Data link layer 48 network layer 49 transport layer 51 session layer 53 presentation layer 54 application layer 55 summary of layer functions 56 3. A link isthe communication channels that connect two adjacent hosts or routers. Data link layer protocols transmission control protocol. Here are the basic functionalities of the data link layer.
Link protocol types synchronous asynchronous masterslave peertopeer 4. Communication networks i data link layer institut fur. There are different types of layers and each of these layers has its own functionality which is. The objective of data link layer is to reliably transmit data between 2 nodes. The objectives of tcplike transport layer protocols in wsn include. Data link layer silvia giordano ica, epfl the data link layeris responsible for transferring a datagram across an individual link.
Internet router architecture 8 router 3 layer physical, data link, network device, with 3 key functions. This address is technically called the media access control address mac because it is found on the mac sub layer of the data link layer. Internet protocol ip 304 internetworking technology overview, june 1999 optionsallows ip to support various options, such as security. Computer networking and management lesson 5 the data. The network layer is interested in getting messages to the corresponding network layer module on an adjacent machine. Data at application, presentation and session layers segment at transport layer packet at network layer frame at data link layer bits at physical layer each layer, with the exception of the physical layer, adds its own header. Examples of link layer protocols include ethernet, token ring, fddi, and ppp. Physical layer also defines the way in which the data flows between the two connected devices. Encapsulate the data supplied by the transport layer inside a network layer ip header. It divides one large network into several smaller ones b. Osi model the data link layer continued the data link layer packages the higher layer data into frames, so that the data can be put onto the physical wire.
Data link and network layer tcpip protocols understand the role that data link protocols, such as slip. It is basically a linked layer protocol which can be used with systems network architecture or the sna environment. Computer networks pdf notes free download cn notes. The bottom layers in ethernet and wifi networks, the data link layer is split into two sublayers. Like physical layer protocols, datalink layer protocols are classified as lan protocols, wan. Data link layer protocols the data link layer provides service to the network layer above it. Which provision can resolve overcome the shortcomings associated with duplication or failure condition of stop and wait automatic repeat request protocol especially due to loss of data frames or nonreception of acknowledgement. Data communication and computer networks pdf notes dccn notes sorry download link file is not available. Defines the methods and provides addressing information for communication between network devices. They use start and stop bits, and variable gaps between characters. Noise free and noisy channels, performance and efficiency. Data link layer protocols free download as powerpoint presentation.