Chap7assignment - Michael S Murphy | NET 125 Chapter 7 OSI...

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Michael S Murphy | NET 125 Chapter 7: OSI Data Link Layer Vocabulary Exercise: Matching Term Definition a. Frame a . Two or more devices connected to a common medium b. Node d . A layer of the Open Systems Interconnection (OSI) model that frames upper-layer data and controls how data is placed on a medium c. Media b . A device on a network d. Network e . The physical means used to carry data signals e. Data Link c . The protocol data unit (PDU) used in Layer 2 of the OSI model Concept Questions 1. What are the two main jobs of the data link layer? Allows the upper layers to access the media using techniques such as framing. Controls how data is placed onto the media and is received from the media using techniques such as media access control (MAC) and error detection. 2. What is the difference between a logical network and a physical network? Logical network refers a group of devices that associated by the arrangement of a hierarchical addressing scheme. Physical network refers the connection of devices on a common media. 3. If the data link layer didn’t exist, what changes would be required of a network layer protocol such as Internet Protocol (IP)? Without the data link layer, a network layer protocol, like IP, would require provisions for connecting to every type of media that could exist along a delivery path. Vocabulary Exercise: Completion 1. The technique for getting a frame on and off a medium is called the MAC method. 2. To connect to a network, an end device uses an adapter, such as a Network Interface Card (NIC) on a Local Area Network (LAN). The adapter manages the framing and media access method . 3. An intermediary device, such as routers , has physical interfaces that can encapsulate a packet into the appropriate frame and handle the MAC method to access each link. 4. A router uses data link layer services to receive a frame from one medium, decapsulate the frame to the Layer 3 PDU, encapsulate the Layer 3 PDU into a new frame, and place the frame on the medium of the next link in the network.
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Concept Questions 1. Compare and contrast controlled media access control and contention-based media access control. Although controlled media access is well ordered and provides predictable throughput, these methods can be inefficient because a device has to wait for its turn before it can use the medium. Contention-based media access allows any device to try to access the medium whenever it has data to send. 2. List the steps in the carrier sense multiple access collision detect (CSMA/CD)
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Chap7assignment - Michael S Murphy | NET 125 Chapter 7 OSI...

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