计算机网络课件英文版Chapter5Link Layer and LANs.ppt

5: DataLink Layer 5-1 Chapter 5 Link Layer and LANs A note on the use of these ppt slides: We ’ re making these slides freely available to all (faculty, students, readers). They ’ re in PowerPoint form so you can add, modify, and delete slides (including this one) and slide content to suit your needs. They obviously represent a lot of work on our part. In return for use, we only ask the following: ? If you use these slides (., in a class) in substantially unaltered form, that you mention their source (after all, we ’ d like people to use our book!) ? If you post any slides in substantially unaltered form on a , that you note that they are adapted from (or perhaps identical to) our slides, and note our copyright of this material. Thanks and enjoy! JFK/KWR All material copyright 1996-2007 Kurose and . Ross, All Rights working: A Top Down Approach 4 th edition. Jim Kurose, Keith Ross Addison-Wesley, July 2007. 5: DataLink Layer 5-2 Chapter 5: The Data Link Layer Our goals: r understand principles behind data link layer services: m error detection, correction m sharing a broadcast channel: multiple access m link layer addressing m reliable data transfer, flow control: done! r instantiation and implementation of various link layer technologies 5: DataLink Layer 5-3 Link Layer r Introduction and services r Error detection and correction r access protocols r Link-layer Addressing r r Link-layer switches r PPP r Link virtualization: ATM, MPLS 5: DataLink Layer 5-4 Link Layer: Introduction Some terminology: r hosts and routers are nodes munication channels that connect adjacent nodes along communication path are links m wired links m wireless links m LANs r layer-2 packet is a frame , encapsulates datagram data-link layer has responsibility of transferring datagram from one node to adjacent node over a link 5: DataLink Layer 5-5 Link layer: context r datagram transferred by different link p