铁铝土是热带亚热带地区的主要土壤类 型。包括砖红壤、赤红壤、红壤和黄壤 等土类。 北起长江两岸,南至南海诸岛,东起台 湾、澎湖列岛,西达云贵高原及横断山 脉。涉及十四个省区,面积约15.28亿亩。 约占全国土地总面积的15%。是我国重 要的土壤资源

上一章讨论的局域网是单个的同种协议网,即网络中每台机器对应层所用协议相同,通信 是在同一个网络内不同主机之间进行的。而所谓“网络互连”,就是采用各种网络互连设备将 同一类型的网络或不同类型的网络相互连接起来,形成所谓“ internet“(互连网络),使一个 网络上的主机能与另一网络上的主机相互通信。因特网( Internet)是世界上最大的 internet 此外,为了保证网络的传输性能、可靠性及安全性,一般要求一个网络所管理的范围不要 太大,这就要求把一个大的网络分解成若干个较小的子网,通过网络互连技术,形成所谓的 Intranet(内部互连网),以便隔离故障,提高安全保密性,方便网络管理

任何一台机器的设计,除了运动分析、结构设计、强度、刚度计算外,还要进行精度设 计。研究机器的精度时,要处理好机器的使用要求与制造工艺的矛盾。解决的方法是规定合 理的公差,并用检测手段保证其贯彻实施。由此可见,“公差”在生产中是非常重要的

Network is divided into several smaller subnetworks Each subnetwork(subnet) has its own subnetwork address Hierarchy in IP addressing IP addresses are designed with two levels of hierarchy

CONTENTS LANS POINT-TO- POINT WANS SWITCHED WANS CONNECTING DEVICES

Mobile IP Discussion Overview Will cover: Why IP routing breaks under mobility Mobile IPv44 basics Some low-level- protocol details(message formats, headers, etc.) Lots more detail in the specifications(see RFC)

Introduction X Presents the sequence of steps a programmer takes to first create a conventional program and then divide the program into local and remote components w Uses an example application to show the output from rpcgen and additional code required to create the client and server components of a distributed program that uses rpc

Introduction Continues the discussion of middleware (i.e., tools and libraries programmers used to construct client-server software) Y Introduces the remote procedure call (RPC) concept, and describes a particular implementation of an rpc that uses XDr standard for data representation

Introduction Examines a de facto standard for external data representation and presentation as well as a set of library procedures used to perform data conversion Describes the general motivations for using an external data representation and the details of one particular implementation

Contents NAME SPACE DOMAIN NAME SPACE DISTRIBUTION OF NAME SPACE DNS IN THE INTERNET RESOLUTION DNS MESSAGES TYPES OF RECORDS COMPRESSION EXAMPLES