The administrator.Step 3: Examine the captured data. To support our communication, the OSI model divides the functions of a data network into layers.Modules 4 7: Ethernet Concepts Exam Answers A network administrator is measuring the transfer of bits across the company backbone for a mission critical financial application. Wireshark does not display the preamble field of a frame. This process continues from router to router until the packet reaches its destination IP address. The default gateway receives the packet, strips the Layer 2 frame information from the packet and then creates a new frame header with the MAC address of the next hop.Physical networks represent the interconnection of devices on a common media. Logical networks are defined at the Network layer by the arrangement of the hierarchical addressing scheme. In this chapter media does not refer to content programming such as audio, animation, television, and video as used when referring to digital content and multimedia.** A physical network is different from a logical network. Media is the physical copper cable, optical fiber, or atmosphere through which the signals travel. Here, these words refer to the material that actually carries the signals representing the transmitted data. Controls how data is placed onto the media and is received from the media using techniques such as media access control and error detectionAs with each of the OSI layers, there are terms specific to this layer:Node - The Layer 2 notation for network devices connected to a common mediumMedia/medium (physical)* - The physical means for the transfer of information between two nodesNetwork (physical)** - Two or more nodes connected to a common mediumThe Data Link layer is responsible for the exchange of frames between nodes over the media of a physical network.* It is important to understand the meaning of the words medium and media within the context of this chapter.
At each hop along the path, an intermediary device - usually a router - accepts frames from a medium, decapsulates the frame, and then forwards the packet in a new frame appropriate to the medium of that segment of the physical network.Imagine a data conversation between two distant hosts, such as a PC in Paris with an Internet server in Japan. This layer provides services to support the communication processes for each medium over which data is to be transmitted.In any given exchange of Network layer packets, there may be numerous Data Link layer and media transitions. The Data Link layer relieves the upper layers from the responsibility of putting data on the network and receiving data from the network. Between the PC and the router may be an Ethernet link. Each transition at a router could require a different Data Link layer protocol for transport on a new medium.Notice in the figure that each link between devices uses a different medium. This packet exchange between two hosts requires a diversity of protocols that must exist at the Data Link layer. Borat full movie downloadThis process would hamper protocol and network media innovation and development. Moreover, IP would have to adapt every time a new network technology or medium was developed. A packet is received from and directed to an upper layer protocol, in this case IPv4 or IPv6, that does not need to be aware of which media the communication will use.Without the Data Link layer, a Network layer protocol, such as IP, would have to make provisions for connecting to every type of media that could exist along a delivery path. For the final link, the packet will use a wireless data link frame from the router to the laptop.The Data Link layer effectively insulates the communication processes at the higher layers from the media transitions that may occur end-to-end. In this example, as an IP packet travels from the PC to the laptop, it will be encapsulated into Ethernet frame, decapsulated, processed, and then encapsulated into a new data link frame to cross the satellite link. Miss pooja sorry ji wrong number song downloadFor example, one network environment may consist of many hosts contending to access the network medium on an ad hoc basis. For the data to be transferred across a number of different media, different media access control methods may be required during the course of a single communication.Each network environment that packets encounter as they travel from a local host to a remote host can have different characteristics. The technique used for getting the frame on and off media is called the media access control method. For that reason, please note that any given protocol may or may not support all these Data Link layer services.7.1.2 Data Link Layer - Controlling Transfer across Local MediaLayer 2 protocols specify the encapsulation of a packet into a frame and the techniques for getting the encapsulated packet on and off each medium. Because of the number of communication services provided by the Data Link layer, it is difficult to generalize their role and provide examples of a generic set of services. Determine Ip And Header Information For A Data Packet Frame Serial Interface ToThe router in the figure has an Ethernet interface to connect to the LAN and a serial interface to connect to the WAN. The adapter manages the framing and media access control.At intermediary devices such as a router, where the media type could change for each connected network, different physical interfaces on the router are used to encapsulate the packet into the appropriate frame, and a suitable media access control method is used to access each link. For example, to connect to a LAN, the device would use the appropriate Network Interface Card (NIC) to connect to the LAN media. When communication between individual nodes begins and when it ends Which nodes are in communication with each other Control information may tell: Data Link layer protocols require control information to enable the protocols to function. Trailer - Contains control information added to the end of the PDUThese frame elements will be discussed in more detail later in this chapter. Header - Contains control information, such as addressing, and is located at the beginning of the PDU Data - The packet from the Network layer
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