Assignment: read Part I: Introduction chapter 1 in text ur goa Overview: get contex↑ what's the Internet overview.\feel\of what's a protocol?

Link Layer: setting the context actual PDu flow Router r1 applicatio pp lication transport trar sport network net vork data link

Summary of mac protocols What do you do with a shared media? Channel Partitioning by time, frequency or code Time Division, Code Division, Frequency Division Random partitioning dynamic

Network layer functions transport packet from sending to receiving hosts network layer protocols in physical every host, router data link physical data link

TCP segment structure 32 bits URG: urgent data (generally not used) source port #f dest port counting by bytes sequence number

IP datagram format IP protocol version 32 bits Imber total datagram header lenath lver/head pe length(bytes) (bytes) Hlen service

Chapter Overview: understand principles transport layer services behind transport layer 0multiplexing/demultiplexing services: 0connectionless transport: UDP multiplexing/demultiplex

Part 2: Application Layer Our goals: More chapter goals conceptual specific protocols implementation http aspects of network ftp

第12讲网页设计与编程(三) 一、CG概念和PHP程序设计基础

一、什么是安全性? 二、密码术 三、报文鉴别