【導(dǎo)讀】自從它最初在1981年[RFC791]被定義后，它的意義已經(jīng)發(fā)生了本質(zhì)的改變。它的目的是隨著Inter近幾年的成指數(shù)級(jí)的增長所帶來的實(shí)質(zhì)上的改變，避免大家對(duì)IP地址的誤解。將有一小節(jié)介紹IPv6與IPv4地址的主要的相似點(diǎn)和。被獨(dú)立的分析[RFC1498]。的定義可以被細(xì)分為至少兩個(gè)的觀點(diǎn)也是很重要的，命名“標(biāo)示”和“定位”，在rfc791出版以前這個(gè)可能是少為人知的。的是一些轉(zhuǎn)發(fā)IPv4包從從一個(gè)主機(jī)或路由到其它主機(jī)或路由的系統(tǒng)。TCP頭[RFC793]或在IP安全協(xié)會(huì)[RFC1825]。習(xí)慣上，在每一個(gè)數(shù)據(jù)包中的源IPv4. 交流的主機(jī)的最大生存時(shí)間內(nèi)有效。時(shí)的唯一性是說對(duì)于TCP實(shí)現(xiàn)來說不象IP地址一樣，需要保持關(guān)于遠(yuǎn)端的狀態(tài)。使用之間發(fā)生沖突時(shí)，定位的使用是主要的。已經(jīng)被認(rèn)為更加有效。換句話說，在路由協(xié)議中這將是集中工作，在地址習(xí)慣用法的其它方面幾乎。網(wǎng)絡(luò)層結(jié)構(gòu)看來，ALG是很簡(jiǎn)單的，在每一個(gè)區(qū)域中它們將表現(xiàn)為Inter主機(jī)，NAT將修改雙方的IP頭中的地址。

　　

【正文】 Inter routing system, the subscriber may need to renumber. Changing providers is just one possible reason for renumbering. The informational document [RFC1900] shows why renumbering is an increasingly frequent event. Both DHCP [RFC1541] and PPP [RFC 1661] promote the use of dynamic address allocation. To summarize, since the development and deployment of DHCP and PPP, and since it is expected that renumbering is likely to bee a mon event, IP address significance has indeed been changed. Spatial uniqueness should be the same, so addresses are still effective locators. Temporal uniqueness is no longer assured. It may be quite short, possibly shorter than a TCP connection time. In such cases an IP address is no longer a good identifier. This has some impact on endtoend security, and breaks TCP in its current form. . Multicast and Anycast Since we deployed multicast [RFC1112], we must separate the debate over meaning of IP addresses into meaning of source and destination addresses. A destination multicast address (. a locator for a topologically spread group of hosts) can traverse a NAT, and is not necessarily restricted to an intra (or to the public Inter). Its lifetime can be short too. The concept of an anycast address is of an address that semantically locates any of a group of systems performing equivalent functions. There is no way such an address can be anything but a locator。 it can never serve as an identifier as defined in this document, since 共 6 頁 第 11 頁 it does not uniquely identify host. In this case, the effective temporal uniqueness, or useful lifetime, of an IP address can be less than the time taken to establish a TCP connection. Here we have used TCP simply to illustrate the idea of an association many UDP based applications (or other systems layered on IP) allocate state after receiving or sending a first packet, based on the source and/or destination. All are affected by absence of temporal uniqueness whereas only the routing infrastructure is affected by spatial uniqueness changes. . Summary Due to dynamic address allocation and increasingly frequent work renumbering, temporal uniqueness of IPv4 addresses is no longer globally guaranteed, which puts their use as identifiers into severe question. Due to the proliferation of Intras, spatial uniqueness is also no longer guaranteed across routing realms。 interconnecting routing realms could be acplished via either ALGs or NATs. In principle such interconnection will have less functionality than if those Intras were directly connected. In practice the difference in functionality may or may not matter, depending on individual circumstances. 5. IPv6 Considerations As far as temporal uniqueness (identifierlike behaviour) is concerned, the IPv6 model [RFC1884] is very similar to the current state of the IPv4 model, only more so. IPv6 will provide mechanisms to autoconfigure IPv6 addresses on IPv6 hosts. Prefix changes, requiring the global IPv6 addresses of all hosts under a given prefix to change, are to be expected. Thus, IPv6 will amplify the existing problem of finding stable identifiers to be used for endtoend security and for session bindings such as TCP state. The IAB feels that this is unfortunate, and that the transition to IPv6 would be an ideal occasion to provide upper layer endtoend protocols with temporally unique identifiers. The exact nature of these identifiers requires further study. As far as spatial uniqueness (locatorlike behaviour) is concerned, the IPv6 address space is so big that a shortage of addresses, requiring an RFC1918like approach and address translation, is hardly conceivable. Although there is no shortage of IPv6 addresses, there is also a welldefined mechanism for obtaining linklocal and sitelocal addresses in IPv6 [RFC1884, section ]. These properties of IPv6 do not prevent separate routing realms for IPv6, if so desired (resulting in multiple security domains as well). While at the 共 6 頁 第 12 頁 present moment we cannot identify a case in which multiple IPv6 routing realms would be required, it is also hard to give a definitive answer to whether there will be only one, or more than one IPv6 routing realms. If one hypothesises that there will be more than one IPv6 routing realm, then such realms could be interconnected together via ALGs and NATs. Considerations for such ALGs and NATs appear to be identical to those for IPv4. 共 6 頁 第 13 頁 指 導(dǎo) 教 師 評(píng) 語 外文翻譯成績(jī)： 指導(dǎo)教師簽字： 2020 年 12 月 10 日 注： 1. 指導(dǎo)教師對(duì)譯文進(jìn)行評(píng)閱時(shí)應(yīng)注意以下幾個(gè)方面：①翻譯的外文文獻(xiàn)與畢業(yè)設(shè)計(jì)（論文）的主題是否高度相關(guān)，并作為外文參考文獻(xiàn)列入畢業(yè)設(shè)計(jì)（論文）的參考文獻(xiàn)；②翻譯的外文文獻(xiàn)字?jǐn)?shù)是否達(dá)到規(guī)定數(shù)量（ 3 000 字以上）；③譯文語言是否準(zhǔn)確、通順、具有參考價(jià)值。 2. 外文原文應(yīng)以附件的方式置于譯文之后。