Chapter 1 Introduction

 

1. Introduction   簡介

The Internet is a structured, organized system.  Before we discuss how it works and its relationship to TCP/IP, we first give a brief history of the Internet. We then define the concepts of protocols and standards and their relationships to each other. We discuss the various organizations that are involved in the development of Internet standards. These standards are not developed by any specific organization, but rather through a consensus of users. We discuss the mechanism through which these standards originated and matured. Also included in this introductory chapter is a section on Internet administrative groups.

 互聯網是一個結構化、有組織的系統。在討論互聯網的工做原理和與TCP/IP的關係以前，咱們首先介紹一下互聯網的簡史。而後，咱們定義協議和標準的概念及其彼此之間的關係。咱們討論參與互聯網標準發展的各類組織。這些標準不是由任何組織開發的，而是用戶造成的共識。咱們討論這些標準的起源和成熟的機制。本入門課程還包括有關互聯網管理小組的部分。 

 

OBJECTIVES    （章節目標）

The chapter has several objectives:　　(本章有幾個目標)

• To give a brief history of the Internet.　　（簡要介紹互聯網歷史）
• To give the definition of the two often-used terms in the discussion of the Internet: protocol and standard.    （在互聯網討論中給出兩個常用的術語的定義: 協議和標準）
• To categorize standard organizations involved in the Internet and give a brief discussion of each.         （對參與互聯網的標準組織進行分類，並對每一個組織進行簡要的討論）
• To define Internet Standards and explain the mechanism through which these standards are developed.（定義互聯網標準，並解釋這些標準的機制）
• To discuss the Internet administration and give a brief description of each branch. （討論互聯網管理， 並簡要說明每一個分支機構。）

 

 

1.1 A BRIEF HISTORY

 一個簡短的歷史

A network is a group of connected, communicating devices such as computers and printers. An internet (note the lowercase i) is two or more networks that can communicate with each other. The most notable internet is called the Internet (uppercase I), composed of hundreds of thousands of interconnected networks. Private individuals as well as various organizations such as government agencies, schools, research facilities, corporations, and libraries in more than 100 countries use the Internet. Millions of people are users. Yet this extraordinary system only came into being in 1969.

 網絡是一組鏈接的通信設備，如計算機和打印機。 互聯網（注意小寫字母i）是兩個或多個能夠互相通訊的網絡。最著名的互聯網叫作互聯網（大寫I）, 由數十萬個互聯網絡組成。我的以及100多個國家的政府機構，學校，研究機構，公司和圖書館等各類組織使用互聯網。

ARPANET  

 

In the mid-1960s,mainframe computers in research organizations were stand-alone devices. Computers from different manufacturers were unable to communicate with one another.The Advanced Research Projects Agency (ARPA) in the Department of Defense (DOD) was interested in finding a way to connect computers together so that the researchers they funded could share their findings, thereby reducing costs and eliminating duplication of effort. 

 

在20世紀60年代中期，研究機構的型計算機是獨立設備。來自不一樣製造商的計算機沒法相互通訊。國防部（DOD）高級研究計劃署有興趣找到將計算機鏈接到一塊兒的方法，使他們資助的研究人員能夠分享他們的發現，從而下降成本，消除重複工做。

　　In 1967, at an Association for Computing Machinery (ACM) meeting, ARPA presented its ideas for ARPANET,a small network of connected computers. The idea was that each host computer (not necessarily from the same manufacturer) would be attached to a specialized computer, called an interface message processor (IMP). The IMPs, in turn, would be connected to each other. Each IMP had to be able to communicate with other IMPs as well as with its own attached host. 

 

　　在1976年，在計算機協會（ACM）會議上，ARPA向ARPANAET提出了一個小型網絡鏈接計算機的想法。這個想法是每一個主機（不必定來自同一製造商）將附加到稱爲接口消息處理器（IMP）的專用計算機。這些IMP又會相互聯結。每一個IMP必須可以與其它IMP以及本身

　　By 1969, ARPANET was a reality. Four nodes, at the University of California at Los Angeles (UCLA), the University of California at Santa Barbara (UCSB), stanford Research Institute (SRI) ,and the University of Utah, were connected via the IMPs to form a network. Software called the Network Control Protocol (NCP) provided communication between the hosts. 

 

Birth of the Internet

 

In 1972, Vint Cerf and Bob Kahn, both of whom were part of the core ARPANET group, collaborated on what they called the Internet Project. They wanted to link different networks together so that a host on one network could communicate with a host on a second, different network. There were many problems to overcome: diverse packet sizes, diverse interfaces, and diverse transmission rates, as well as differing reliability requirements. Cerf and Kahn devised the idea of a device called a gateway to serve as the intermediary hardware to transfer data from one network to another. 

 

Transmission Control Protocol/Internetworking Protocol (TCP/IP)

 

Cerf and Kahn's landmark 1973 paper outlined the protocols to achieve end-to-end delivery of data. This was a new version of NCP.  This paper on transmission control protocol(TCP) included concepts such as encapsulation, the datagram, and the funcions of a gatway. A radical idea was the transfer of responsibility for error correction from the IMP to the host machine. This ARPA Internet now became the focus of the communication effort. Around this time responsibility for the ARPANET was handed over the Defense Communication Agency (DCA).

　　In October 1977, an internet consisting of three different networks (ARPANET, packet radio, and packet satellite) was successfully demonstrated. Communication between networks was now possible. 

　　Shortly thereafter, authorities made a decision to split TCP into two protocol: Transmission Control Protocol (TCP) and Internet Protocol(IP). IP would handled datagram routing while TCP would be responsible for higher level functions such as segmentation, reassembly, and error detection. The new combination became known as TCP/IP.

　　In 1981, under a DARPA contract, UC Berkeley modified the UNIX operating system to include TCP/IP. This inclusion of network software along with a popular operating system did much for the popularity of networking. The open (non-manufacturer-specific) imp[lementation on Berkeley UNIX gave every manufacturer a working code base on which they could build their products.

　　In 1983, authorities abolished the original ARPANET protocols, and TCP/IP became the official protocol for the ARPANET. Those who wanted to use the Internet to access a computer on a different network had to be running TCP/IP. 

 

MILNET

In 1983, ARPANET split into two networks: MILNET for military users and ARPANET for nonmilitary users. 

 

CSNET

 

Another milestone in Internet history was the Creation of CSNET in 1981. CSNET was a network sponsored by the National Science Foundation (NSF). The network was conceived by universities that were ineligible to join ARPANET due to an absence of defense ties to DARPA. CSNET was a less expensive network; there were no redundant links and the transmission rate was slower. It featured connections to ARPANET and Telenet, the first commercial packet data service. 

　　By the middle 1980s, most U.S. universities with computer science departments were part of CSNET. Other institutions and companies were also forming their own networks and using TCP/IP to interconnect. The term Internet, originally associated with government-funded connected networks, now referred to the connected networks using TCP/IP protocols.

 

NSFNET

 

With the success of CSNET, the NSF, in 1986, sponsored NSFNET, a backbone that connected five supercomputer centers located throughout the United States. Community networks were allowed access to this backbone, a T-1 line with a 1.544-Mbps data rate, thus providing connectivity throughout the United States. 

　　In 1990, ARPANET was officially retired and replaced by NSFNET. In 1995, NSFNET reverted back to its concept of a research network. 

 

ANSNET

 

In 1991, the U.S. government decided that NSFNET was not capable of supporting the rapidly increasing Internet traffic. There companies, IBM, Merit, and MCI, filled the void by forming a nonprofit organization called Advanced Network and Services (ANS) to build a new, high-speed Internet backbone called ANSNET.

 

 

The Internet Today

 

The Internet today is not a simple hierarchical structure. It is made up of many wide and local area networks joined by connecting devices and switching stations. It is difficult to give an accurate representation of the Internet because it is continuously changing--new networks are being added, existing networks need more addresses, and networks of defunct companies need to be removed. Today most end users who want Internet connection use the service providers (ISPs). There are internet service providers, national service providers, regional service providers, and local service providers. The Internet today is run by private companies, not the government. Figure 1.1 shows a conceptual (not geographical) view of the Internet.

 

 

Backbone ISPs

 

Backbone ISPs are created and maintained by specialized companies. There are many backbone ISPs operating in North America; some of the most well-known are sprintLink, PSINet, UUNet Technology, AGIS, and internet MCI. To provide connectivity between the end users, these backbone networks are connected by a complex switching stations (normally run by a third party) called network access points (NAPs). Some regional ISP networks are also connected to each other by private switching stations called peering points. Backbone ISPs normally operate at a high data rate (10Gbps, for example).

 

Regional ISPs

 

Regional ISPs are small ISPs that are connected to oneor more backbone ISPs. They are at the second level of hierarachy with a lesser data rate.

 

 

Local ISPs

 

 

Local ISPs provide direct service to the end users. The local ISPs can be connected to regional ISPs or directly to backbone ISPs. Most end users are connected to the local ISPs. Note that this sense, a local ISP can be a company that just provides Internet services, a corporation with a network to supply services to its own employees, or a nonprofit organization, such as a collage or a university, that runs its own network. Each of these can be connected to a regional or backbone service provider.

 

 

 

World Wide Web

 

 

The 1990s saw the explosion of the Internet applications due to the emergence of the World Wide Web (WWW). The web was invented at CERN by Tim Berners-Lee. This invention has added the commercial applications to the Internet. 

 

 

Time Line 

 

The following is a list of important Internet events in chronological order:

• 1969. Four-node ARPANET established.
• 1970. ARPA hosts implement NCP.
• 1973. Development of TCP/IP suit begins.
• 1977. An internet tested using TCP/IP.
• 1978. UNIX distributed to academic/research sites.
• 1981. CSNET established. 
• 1983. TCP/IP becomes the official protocol for ARPANET.
• 1983. MILNET was born.
• 1986. NSFNET established.
• 1990. ARPANET decommissioned and replaced by NSFNET. 
• 1995. NSFNET goes back to being a research network.
• 1995. Companies known as Internet Service Providers(ISPSs) started.

Growth of the Internet

 

The Internet has growth tremendously.   In just a few decades, the number of networks has increased from tens to hundreds of thousands. Concurrently, the number of computers connected to the networks has grown from hundredsto hundreds of millions. The Internet is still growing. Factors that an impact on this growth include the following:

• • New Protocols　　New protocols need to be added and deprecated ones need to be removed. For example, a protocol superior in many respects to IPv4 has been approved as a standard but is not yet fully implemented (See IPv6, Chapter27)
  • New Technology　　New technologies are under development that will increase the capacity of networks and provide more bandwidth to the Internet's users.
  • Icreasing Use of Multimedia  It is predicted that the Internet, once just a vehicle to share data, will be used more and more for multimedia (audio and video).

1.2 PROTOCOLS AND STANDARDS   (協議和標準)

 

In this section, we define two widely used terms: protocols and standards. First, we define protocol, which is synonymous with "rule". Then we discuss standards, which are agreed-upon rules. 

在這節中，咱們定義了兩個普遍使用的詞語：協議和標準。首先，咱們定義協議， 這是規則的同義詞。接着， 咱們討論標準，這是一致的規則。

 

 

Protocols

 協議

 

Communication between two people or two devices needs to follow some protocol. A protocol is a set of rules that governs communication. For example, in a face-to-face communication between two persons, there is a set of implicit rules in each culture that define how  two persons should start the communication, how to continue the communication, and how to end the communication. Similarly, in a telephone conversation, there are set of rules that we need to follow. There is a rule how to make connection (dialing the telephone number), how to respond to the call (picking up the receiver), how to greet, how to let the communication flow smoothly by listening when the other party is talking, and finally how to end the communication (hanging up).

　　In computer networks, communication occurs between entities in different systems. An entity is anything capable of sending or receiving information. However, two entities cannot simply send bit streams to each other and expect to be understaood. For communication to occur, the entities must agree on a protocol. A protocol defines what is communicated, how it is communicated, and when it is communicated. The key elements of a protocol are syntax, semantic, and timing.

1. Syntax. Syntax refers to the structure or format of the data, meaning the order in which they are presented. For example, a simple protocol might expect the first 8 bits of data to the address of the sender, the second 8 bits to be the address of the receiver, and the rest of stream to be the message itself. The data order is also applied to the order of bits when they are stored or transmitted. Different computers may store data in different bit orders. When these computers communicate, this difference needs to be resolved. 
2. Semantic.  Semantics refers to the meaning of each section of bits. How is a particular pattern to be interpreted, and what action is to be taken based on that interpretation? For example, does an address identify the route to be taken or the final destination of the message?
3. Timing. Timing refers to two characteristics: when data should be sent and how fast it can be sent. For example, if a sender produces data at 100 megabits per second (100 Mbps) but the receiver can process data at only 1 Mbps, the transmission will overload the receiver and data will be largely lost.

Standards 

Standards are essential  in creating and maintaining an open and competitive market for equipment manufacturers and also in guarateeing and international interoperability of data and telecommunications technology and processes. They provide guidelines to manufactures, verdors, government agencies, and other service providers to ensure the kind of inter connectivity necessary in today's marketplace and in international communications .

　　Data communication standards fall into two categories : de facto (meaning "by fact" or "by convention") and de jure (meaning "by law" or "by regulation").

　　1. De facto. Standards that have not been  approved by an organized body but have been adopted as standards through widespread use are de facto standards. Defacto standards are often established originally by manufacturers that seek to define the functionality of a new product or technology. Examples of de facto standards are MS office and various DVD standards. 

　　2. De jure. De jure standards are those that have been legislated by an officially recognized body. 

 

 

 

 

 

       兩我的或者設備之間的通訊須要遵循一些協義。協議是一組管理通訊的規則。例如，在兩我的面對面交流中，每一個文化都有一套隱含的規則，定義兩我的應該如何開始交流, 如何繼續溝通，以及如何結束溝通。一樣，在電話交談中，咱們須要遵循一系列的規則。 有一套規則， 如何進行鏈接（撥打電話號碼），如何響應呼叫（接通接收器），如何打招呼，當對方正在說話的時候，經過聽時，如何讓通訊流暢順利，最後，如何結束通訊（掛斷）。

　　在計算機網絡中，通訊發生在不一樣系統之間的實體方間。一個實體是可以發送或者接收信息的任何東西。然而，兩個實體之間不能將比特流相互直接發送，而且指望不太理想。爲了發生通訊，實體必須就協議達成一致。一個協議定義了所傳達的內容，如保通訊，以及什麼時候通訊。協議的關鍵要素是：語法，語義和時序。

　　1. 語法： 語法是指數據的結構和格式， 意思是表示數據的順序。例如，一個簡單的協議，可能會將第一個8位的比特數據預期定爲發送方地址，另外一個8位比特數據定爲接收方地址，其他的數據流就是信息自己。數據順序也適應於比特順序，當他們被儲存或傳輸時。不一樣的計算機可能用不一樣的位順序儲存。 當這些計算機通訊時， 須要解決這些差別。

 

 

 

1.3 STANDARDS ORGANIZATIONS 

標準組織

 

Standards are developed through the cooperation of standards creation committees, forums, and government regulatory agencies. 

標準是經過標準制定委員會，論壇和政府監管機構合做制定的。

 

Standards Creation Committees

 標準建立委員會。

While many organizations are dedicated to be the establishment of standards, data communications in North America rely primarily on those published by the following: 

雖然許多組織致力於創建標準，但北美地區的數據通訊主要依靠如下方式發佈：

1. International Standards Organization (ISO).   The International Standards Organization (ISO; also referred to as the International Organization for Standardization) is a multinational body whose membership is drawn mainly from the standards creation committees of various governments throughout the world.  Created in 1947, the ISO is an entirely voluntary organization dedicated to worldwide agreement on international standards.  With a membership that currently includes representative bodies from many industrialized nations, it aims to facilitate the international exchange of goods and services by providing models for compatibility, improved quality, increased productivity, and decreased prices.The ISO is active in developing cooperation in the realms of scientific, technological, and economic activity. Of primary concern to this book are the ISO's efforts in the field of information technology, which have resulted in the creation of the Open Systems Interconnection(OSI) model for network communications. The United states is represented in the ISO by ANSI.   國際標準組織。 國際化標準組織（ISO,也被稱爲國際標準組織）是一個跨國機構，其成員主要來自各國政府的標準化制定組織。ISO 建立於1947年，是一個致立於全球國際標準協議的徹底自願組織。目前， 成員包括許多工業化國家的表明機構，目的在於經過提供兼容性，提升質量，提升生產力和下降價格的模式，促進貨物和服務的國際交流。ISO 在積極開展科技、經濟領域的合做。本書主要關注的是ISO 在信息技術領域的努力，從而爲網絡通訊建立了開放系統互連（OSI）模型。美國在ISO由ANSI體現。
2. International Telecommunications Union-Telecommunications Standards Sector  (ITU-T).  By the early 1970s, a number of countries were defining national standards for telecommunications, but there was still little international compatibility. The United Nations responded by forming, as part of its International Telecommunication Union (ITU), a committee, the Consultative Committee for International Telegraphy and Telephony (CCITT).This committee was devoted to the research and establishment of standards for telecommunications in general and data systems in particular .On March 1 1993, the  name of this committee was changed to the International Telecommunications Union-Telecommunications Union-Telecommunications Standards Sector (ITU-I). 國際電信聯盟--電信標準組織（ITUT）   到20世紀70年代，一些國家正在界定電信的國家標準，但國際上的兼容性依然不多。做爲國際聯盟（ITU）的一部分，聯合國成立了一個委員會，即國際電報電話諮詢委員會（CCITT）。 
3. American National Standards Institute (ANSI).  Despite its name, the American National Standards Institute (ANSI) is a completely private, nonprofit corporation not affiliated with the U.S. federal government. However, all ANSI activities are undertaken with the welfare of the United States and its citizens occupying primary importance. ANSI's expressed aims include serving as the national coordinating institution for voluntary standardization in the United States, furthering the adoption of standards as a way of advancing the U.S. economy, and ensuring the participation and protection of the public interests. ANSI members include professional societies, industry associations, governmental and regulatory bodies, and consumer groups.美國國家標準學會（ANSI）。 儘管如此，美國國家標準學會（ANSI）是一個徹底非營利性的公司，不隸屬於美國聯邦政府。然而，全部ANSI的活動都是以美國及其公民的福利爲重。ANSI的述求目標包括成爲美國自願標準化國家協調機構，推進標準化做爲推進美國經濟的途徑，確保公衆利益參與和保護。ANSI 成員包括專業協會，行業協會，政府和監管機構以及消費者團體。
4. Institute of Electrical and Electronics Engineers (IEEE)     The Institute of Electrical and Electronics Engineers (IEEE) is the largest professional engineering society in the world.  International in scope, it aims to advance theory, creativity, and product quality in the fields of electrical engineering, electronics, and radio as well as in all related branches of engineering. As one of its goals, the IEEE oversees the development and adoption of international standards for computing and communication. As one of its goals, the IEEE oversees the development and adoption of international standards for computing and communication.             電氣與電子工程師學會（IEEE）   電氣與電子工程師協會（IEEE） 是世界上最大的專業工程學會。 在國際範圍內，旨在推動電氣工程，電子，無線電以及相關工程部門的理論，創造力和產品質量。做爲其目標之一，IEEE 監督制定和採用國際計算和通訊的標準。
   
5. Electronic Industries Association (EIA)     Aligned with ANSI, the Electronic Industries Association (EIA) is a nonproft organization devoted to the promotion of electronics manufacturing concerns. Its activities include public awareness education and lobbying efforts in addition to standards development. In the field of information technology, the EIA has made significant contributions by defining physical connection interfaces and electronic signaling specifications for data communication. 電子工業協會     電子工業協會（EIA）和美國國家標準學會（ANSI) 簽署，而且是一家致力於電子製造業關注的非營利組織。其活動除了標準制定外，還包括公衆意識教育和遊說工做。在信息技術領域，EIA經過定義物理鏈接接口和數據通信的電子信號規範給出了重大規範。
6. World Wide Web Consortium (W3C)    Tim Berners-Lee founded this consortium at Massachusetts Institute of Technology Laboratory for Computer Science.  It was founded to provide computability in industry for new standards. W3C has created regional offices around the world.蒂姆.伯納絲.李  在馬薩諸塞理工學院計算機科學研究所創立了這個聯盟。它的成立是爲了在工業上爲新標準提供可計算性。W3C在全球設立區域辦事處。
   
7. Open Mobile Alliance (OMA). The standards organization OMA was created to gather different forums in computer networking and wireless technology under the umbrella of one single authority. Its mission is to provide unified standards for application protocols. 開放移動聯盟（OMA） 建立標準組織（OMA)的目的是爲了在一個權威的機構的保護傘下收集計算機網絡和無線技術的論壇。其使命是爲應用協議提供統一的標準。

 

 

Forums 

論壇

Telecommunications technology development is moving faster than the ability of standards committees to ratify standard. Standards committees are procedural bodies and by nature slow moving. To accommodate the need for working models and agreements and to facilitate the standardization process, many special-interest groups have developed forums made up of representation from interested corporation. The forums work with universities and users to test, evaluate, and standardize new technologies. By concentrating their efforts on a particular technology, the forums are able to speed acceptance and use of those technologies in the telecommunications community. The forums present their conclusions to the standards bodies. Some important forums for the telecommunications industry include the followwing:  

電信技術發展的速度比標準委員會批准標準的能力要快。標準委員會是程序性機構，本質上是緩慢的移動。爲了適應工做模式和協議的需求，並促進標準化進程， 許多特殊利益集團已經開發了由感興趣公司的表明組成的論壇。論壇與大學和用戶合做，測試，評估和規範新技術。經過集中精力開展行定技術，論壇可以加速電信界對技術的接受和使用。這些論壇將其結論提交給標準組織。

　　1.  Frame Relay Forum.  The Frame Relay Forum was formed by Digital Equipment Corporation, Northern Telecom, Cisco, and StrataCom to promote the acceptance and implementation of Frame Relay. Today, it has around 40 members representing  North America, Europe, and Pacific Rim. Issues under review include flow control, encapsulation, translation, and multicasting. The forum's results are submitted to the ISO. 幀中繼論壇     幀中繼論壇，是由數字設備公司，北方電信，Cisco, 和 StrataCom 公司造成了幀中繼和執行。今天，它具備表明北美、歐洲和太平洋沿岸各地的40名成員。正在審議的問題包括流量控制、封裝、，翻譯和流量控制。論壇的結果提交給ISO.

　　2. ATM Forum        The ATM forum promotes the acceptance and use of Asynchronous Transfer Mode (ATM) technology. The ATM Forum is made up of customer premises equipment (e.g. PBX systems) vendors and central office (e.g., telephone exchange) providers. It is concerned with the standardization of services to ensure interoperability.   ATM 論壇，促進了異步傳輸的模式（ATM）技術的接愛和使用。ATM 論壇由客戶駐地設備（例如PBX系統）和中心局（例如電話交換）提供商組成。它關心的是服務的標準化， 以確保互操做性。

　　3. Universal Plug and play (UPnP) Forum.　　The UPnP forum is a computer network forum that supports and promotes simplifying the implementation of networks by creating zero-configuration networking devices. A UPnP-compatiable device can join a network without any configuration.   通用即插即用（UPnP）論壇。  UPnP 是一個計算機網絡論壇，經過建立零配置網絡設備來支持和促進簡化網絡的設施。

 

 

Regulatory Agencies

 監管機構

All  communication technology is subject to regulation by government agencies such as the Federal Communication Commission in the United States. The purpose of these agencies is to protect the public interest by regulating radio, television, and wire/cable communication. 

　　#  Federal Communication Commission (FCC). The Federal Communications Commission (FCC) has authority over interestate and international commrece as it relates to communication 

　　@The websites for the above organizations are given in Appendix G. 

 全部的通訊技術都受到美國聯邦通訊委員會等政府機構的監管。

 

 

 

1.4 Internet Standards

互聯網標準 

An Internet standard is a thoroughly tested specification that is useful to and adhered to by those who work with the Internet. It is a formalized that must be followed. There is a strict procedure by which a specification attains Internet standard status. A specification begins as an Internet draft. An Internet draft is a working document (a work in progress) with no official status and a six-month lifetime. Upon recommendation from the Internet authorities, a draft may be published as a Request for Comment (RFC). Each RFC is edited, assigned a number, and made available to all interested parties.

互聯網標準是一個通過完全測試的規範，對於使用互聯網的人是有用的和遵照的。規範達到互聯網標準的嚴格程序。規範以互聯網草案開始。

　　RFCs go through maturity levels and categorized according to their requirement level. 

　Maturity Levels

　成熟度級別

　　An RFC， during its lifetime, falls into one of six maturity levels: proposed standard, draft standard, Internet standard, historic, experimental, and information (see Figure 1.2).

　　RFC，在其一輩子中屬於六個成熟度級別之一：提出的標準、標準草案、互聯網標準，歷史，實驗和信息（見圖1.2）

　　Proposed Standard

　　擬議標準

  　  A proposed standard is a specification that is stable, well understood, and of sufficient interest to the Internet community. At this level, the specification is usually tested and implemented by several different groups.

　　一個擬議標準是一個穩定的、很好理理解的規範，以及對互聯網社會足夠的感興趣。在這個級別，規範一般由幾個不一樣的組進行測試和實現。

　　Draft Standard

　　標準草案

　　A proposed standard is elevated to draft standard status after at least two successful independent and interoperable implementations. Barring difficulties, a draft standard, with modifications if specific problems are 　　encountered, normally becomes an Internet standard.

　　在至少兩次相互獨立且交叉操做實現後，擬議標準纔可提高爲草案標準。除了困難，標準草案，若是遇到具體問題，修改一般會成爲互聯網標準。

 

　　Internet Standard

　　A draft standard reaches Internet standard status after demonstrations of successful implementation.

　　Historic 

　　The historic RFCs are significant from a historical perspective. They either have been superseded by later specifications or have never passed the necessary maturity levels to become an Internet standard.

　　Experimental 

　　An RFC classified as experimental describes work related to an experimental situation that does not affect the operation of the Internet. Such an RFC should not be implemented in functional Internet service. 

　　Informational

　　An RFC classified as informational contains general, historical, or tutorial information related to the Internet . It is usually written by someone in a non-Internet organization, such as a vendor.

　　Requirement Levels

　　RFCs are classified into five requirement levels: required, recommended, elective, limited use, and not recommended (see Figure 1.3)

　　Required

　　An RFC is labeled required if it must be implemented by all Internet systems to achieve minimum conformance. For example, IP (Chapter 7) and ICMP (Chapter 9) are required protocols. 

　　Recommended

　　An RFC labeled recommended is not required for minimum conformance; it is recommented because of its usefulness. For example, FTP (Chapter 21) and TELNET (Chapter 20) are recommended protocols.

　　Elective

　　An RFC labeled elective is not requiered and not recommended. However, a system can use it for its own benefit.

　　Limited Use

　　An RFC labeled limited use should be used only in limited situations. Most of the experimental RFCs fall under this category.

　　Not Recommended

　　An RFC labeled not recommended is inappropriate for general use. Normally a historic (deprecated) RFC may fall under this category.

1.5 INTERNET ADMINISTRATION    

　　互聯網管理

　　The Internet, with its roots primarily in the research domain, has evolved and gained a broader user base with significant commercial activity. Various groups that coordinate Internet issues have guided this growth and development. Appendix G gives the addresses, e-mail addresses, and telephone numbers for some of these groups. Figure 1.4 shows the general organization of Internet administration. 

　　Internet Society (ISCO)

　　The Internet Society (ISOC) is an international, nonprofit organization formed in 1992 to provide support for the Internet standards process. ISOC accomplishes this through maintaining and supporting other administrative bodies such as IAB, IETF,and IANA (see the following sections). ISCO also promotes research and other scholarly activities relating to the Internet.

　　Internet Architecture Board(IAB)

　　The Internet Architecture Board (IAB) is the technical advisor to the ISOC. The main purposes of the IAB are to oversee the continuing development of the TCP/IP Protocol Suite and to serve in a technical advisory capacity to research members of the Internet community. IAB accomplishes this through its two primary components, the Internet Engineering Task Force (IETF) and the Internet Research Task Force (IRTF). Anther responsibility of the IAB is the editorial  management of the RFCs, described earlier in this chapter. IAB is also the external liasion between the Internet and other standards organizations and forums.

　　Internet Engineering Task Force(IETF)