對(duì)移動(dòng)IPv6支持的綜合高效切換程序 外文資料翻譯

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1、 本科畢業(yè)設(shè)計(jì)（論文） 外文資料翻譯 外文資料題目 A Comprehensive and Efficient Handoff Procedure for IPv6 Mobility Support 對(duì)移動(dòng)IPv6支持的綜合高效切換程序 摘要 移動(dòng) IPv6 路由優(yōu)化的切換性能取決于優(yōu)化的 IP 層自動(dòng)機(jī)制，以及安排和并行化及其信號(hào)的移動(dòng)節(jié)點(diǎn)的靈活性

2、。本文提供了標(biāo)準(zhǔn)的 ipv6 協(xié)議套件和移動(dòng) IPv6切換性能綜合分析延遲的幾個(gè)來(lái)源。雖然一些拖延已是眾所周知的優(yōu)化和廣泛適用的切換方法是尚未被發(fā)現(xiàn)。本文因此繼續(xù)討論現(xiàn)有和新的優(yōu)化建議，其中一些目前正在內(nèi) IETF、標(biāo)準(zhǔn)化，并闡述如何組合的那些可以 顯著的提高切換的經(jīng)驗(yàn)。 1 .介紹 互聯(lián)網(wǎng)服務(wù)滲透的日常生活越來(lái)越多，用戶越來(lái)越希望他們能夠在任何地點(diǎn)、任何時(shí)間使用互聯(lián)網(wǎng)。同時(shí)，實(shí)時(shí)通信的重要性正在增加，如音頻和視頻流媒體、 IP 電話、 視頻會(huì)議等實(shí)時(shí)通信都是高度敏感數(shù)據(jù)延遲，傳播延遲和切換延遲。高效地移動(dòng)支持是下一代互聯(lián)網(wǎng)建設(shè)過(guò)程中的主要目標(biāo)，設(shè)計(jì)和路由優(yōu)化的一種模式被納入移動(dòng) IPv6

3、移動(dòng)性協(xié)議。路由優(yōu)化允許直接路徑通過(guò)。這是補(bǔ)充路由通過(guò)固定的代理服務(wù)器，其代理移動(dòng)節(jié)點(diǎn)修建的經(jīng)典的方法。當(dāng)路由優(yōu)化減少傳播延遲的同時(shí)，切換延遲仍然相當(dāng)有效地排除了有意義的實(shí)時(shí)支持。事實(shí)上，標(biāo)準(zhǔn)的 IPv6 部署中的切換延遲大約是幾秒。這不只是因?yàn)橐苿?dòng) IPv6，但也會(huì)影響標(biāo)準(zhǔn) IPv6 和運(yùn)動(dòng)檢測(cè)機(jī)制。非常幸運(yùn)的是，最近把大量的優(yōu)化技術(shù)提出以簡(jiǎn)化個(gè)人切換相關(guān)的活動(dòng)。測(cè)量數(shù)據(jù)證實(shí)任何特殊技術(shù)化都是有利的。但是，研究如何優(yōu)化集成到目前為止已經(jīng)很大程度上被忽視的。本文從較高的角度來(lái)看流動(dòng)性檢查的挑戰(zhàn) 它解釋標(biāo)準(zhǔn)的 IPv6 部署 IP 層視野中的整體切換過(guò)程和分析方面的期望。由于結(jié)果強(qiáng)烈建議優(yōu)化，文

4、件將繼續(xù)探索有前途的現(xiàn)有和新的建議，最近獲得了互聯(lián)網(wǎng)工程任務(wù)組 (IETF) 和學(xué)術(shù)研究界的勢(shì)頭。對(duì)他們的相互作用也計(jì)算優(yōu)化。本文建議改進(jìn)的切換性能的集成的解決方案。 2 .標(biāo)準(zhǔn)切換過(guò)程 A 移動(dòng)節(jié)點(diǎn)經(jīng)歷 IP 層切換，或者只需切換，當(dāng)它更改 IP 連接。這開(kāi)頭鏈路層附件中的變化，還鏈路層切換，后面跟著發(fā)現(xiàn)新路由器、地址、運(yùn)動(dòng)檢測(cè)和 移動(dòng) IPv6 登記。圖 1 說(shuō)明了這些切換的步驟，分別討論下一步了。 2.1 路由器發(fā)現(xiàn) A 移動(dòng)節(jié)點(diǎn)在路由器發(fā)現(xiàn)的過(guò)程中學(xué)會(huì)有關(guān)本地路由器和鏈路上的前綴。這一過(guò)程被透過(guò)松散定期上的鏈路本地節(jié)點(diǎn)的路由器多播路由器廣告郵件。IPv6 鄰居發(fā)現(xiàn) RF

5、C 指出未經(jīng)請(qǐng)求的路由器廣告郵件發(fā)送 3 和 4 秒之間的隨機(jī)間隔至少和 1350年 1800年秒之間最。由于這些保守的限制旨在平穩(wěn)的節(jié)點(diǎn)，而不能有意義地支持移動(dòng)，移動(dòng) IPv6 RFC 減少下限，一個(gè)信標(biāo)每 30 至 70 毫秒為單位）。因此，移動(dòng)節(jié)點(diǎn)可以期待收到 25 毫秒之后的第一次切換的廣告，這減少了50 毫秒連續(xù)廣告之間的平均時(shí)間。另一方面，高頻率的多址廣播廣告可能是在低帶寬、 廣域網(wǎng)絡(luò)，其中許多用戶可能經(jīng)常離開(kāi)受同一 IP 子網(wǎng)的地理區(qū)域的問(wèn)題。圖 1 顯示的廣告相關(guān)的切換過(guò)程中 ；掩蓋了其他的廣告。 2.2 地址配置 移動(dòng)節(jié)點(diǎn)配置新的全球 IP 地址收到的未知的前綴路由器

6、廣告郵件。這種情況通常發(fā)生符合無(wú)狀態(tài)地址自動(dòng)： 移動(dòng)節(jié)點(diǎn)或者隨機(jī)選擇的接口標(biāo)識(shí)符，或基于接口的 MAC 地址，及在此將添加前獲得的前綴。然后，它會(huì)發(fā)送多播偵聽(tīng)程序報(bào)告消息要訂閱請(qǐng)求節(jié)點(diǎn)多播組相對(duì)應(yīng)的新地址。如果路由器通告消息是多播的傳輸，通常是這種情況，多播偵聽(tīng)程序報(bào)告消息被延誤第二解脫與相鄰的節(jié)點(diǎn)，可能對(duì)相同的廣告作出的反應(yīng)。移動(dòng)節(jié)點(diǎn)，然后運(yùn)行重復(fù)地址檢測(cè)協(xié)議，以驗(yàn)證是否是唯一的新地址： 它傳輸?shù)刂返泥従诱?qǐng)求消息，并且，如果在 1 秒的時(shí)間內(nèi)收到?jīng)]有響應(yīng)，為標(biāo)志的接口的地址。如果是一個(gè)唯一的地址，因此總 期范圍 1 和 2 秒之間。可能已在另一個(gè)節(jié)點(diǎn)使用 IPv6 地址的可能性很小，可以使

7、其可以忽略不計(jì)。即使該鏈接本地地址保持其前綴在切換過(guò)程中，移動(dòng)節(jié)點(diǎn)必須重新仍驗(yàn)證此地址的唯一性時(shí) IP 連接更改，因?yàn)樾碌逆溌飞系墓?jié)點(diǎn)可能已經(jīng)使用相同的鏈接本地地址。這是通過(guò)另一個(gè)運(yùn)行的重復(fù)地址檢測(cè)。因?yàn)橹挥羞\(yùn)動(dòng)檢測(cè)可以建立 IP 連接是否已更改，re-核查的鏈接本地地址通常運(yùn)動(dòng)檢測(cè)后開(kāi)始。這不是顯示在圖像，但是，鑒于鏈接本地地址的可用性并不是影響其他切換 活動(dòng)的日程安排。 2.3 運(yùn)動(dòng)檢測(cè) 移動(dòng)節(jié)點(diǎn)執(zhí)行運(yùn)動(dòng)檢測(cè)，以識(shí)別 IP 連接的更改。這種變化意味著移動(dòng)節(jié)點(diǎn)選擇新的默認(rèn)路由器、 無(wú)效陳舊的全局地址，其鏈路本地地址，再核實(shí)唯一性和啟動(dòng)移動(dòng) IPv6 登記。運(yùn)動(dòng)檢測(cè)依賴于分析廣告路由器廣

8、告郵件中的鏈接上前綴和可能還探討了路由器考慮關(guān)閉鏈接的可到達(dá)性。當(dāng)移動(dòng)節(jié)點(diǎn)使用的前綴不再被視為刊登公告，但新的前綴 顯示相反時(shí)，移動(dòng)節(jié)點(diǎn)通常決定它已移動(dòng)到不同的網(wǎng)絡(luò)。另一方面，收到的前綴 也可能表示 IP 連接未改變鏈接層切換，盡管中例如，當(dāng)移動(dòng)節(jié)點(diǎn)交換機(jī)連接到同一子網(wǎng)的接入點(diǎn)。運(yùn)動(dòng)檢測(cè)被復(fù)雜的路由器通告消息可能包含不完整集前綴 的這一事實(shí)。接待處的單個(gè)因此通常是廣告的不足，以決定是否已更改 IP 連接。它也是通常不可能確定當(dāng)廣告應(yīng)已收到，但沒(méi)有出現(xiàn)，以保證的廣告時(shí)間間隔的缺乏。移動(dòng) IPv6 RFC 幫助，在這方面，它引入了路由器廣告郵件廣告時(shí)間間隔選項(xiàng)。路由器使用此選項(xiàng)可以指示對(duì)其信標(biāo)期間

9、的上限。這是低至 70 毫秒 （參見(jiàn)第 2.1 節(jié)），為了計(jì)算調(diào)度中移動(dòng)節(jié)點(diǎn)和路由器的粒度添加額外 20 毫秒。然后，移動(dòng)節(jié)點(diǎn)期望路由器通告消息到達(dá)的最 90 毫秒的時(shí)間間隔。不過(guò)，沒(méi)有一種單一的預(yù)期廣告仍然并不意味著變化可能給數(shù)據(jù)包丟失的 IP 連接。三個(gè)丟失的廣告更可靠地表明運(yùn)動(dòng)。然后決定最 270 毫秒后從舊的默認(rèn)路由器接收到最后的廣告。實(shí)際的鏈路層切換稍后就會(huì)出現(xiàn)最多 70 毫秒，以便運(yùn)動(dòng)檢測(cè)可以采取任何 200 和 270 毫秒之間的時(shí)間。平均而言，從舊的默認(rèn)路由器的最后一個(gè)廣告的接待和鏈路層切換期間是 25 毫秒，收益率平均運(yùn)動(dòng)檢測(cè) 245 毫秒的延遲。 2.4 移動(dòng)IPV6注冊(cè)

10、 移動(dòng) IPv6 注冊(cè)后地址 和運(yùn)動(dòng)檢測(cè)移動(dòng)節(jié)點(diǎn)選擇其新的全球地址注冊(cè)轉(zhuǎn)交地址作為其家鄉(xiāng)代理和對(duì)應(yīng)的節(jié)點(diǎn)之一。這樣就建立關(guān)懷的地址與移動(dòng)節(jié)點(diǎn)的家鄉(xiāng)地址，已從家鄉(xiāng)代理的網(wǎng)絡(luò)的前綴和跨運(yùn)動(dòng)保持穩(wěn)定之間的綁定。住宅地址 IP 之上的堆棧層用作終點(diǎn) 鑒定的一部分。與同行交流的移動(dòng)節(jié)點(diǎn)的數(shù)據(jù)包有 IP 報(bào)頭中的護(hù)理的地址和在電線上的 IPv6 擴(kuò)展標(biāo)頭中的家庭住址。同時(shí)結(jié)束節(jié)點(diǎn)交換地址時(shí)遍歷的數(shù)據(jù)包的 IP 層這樣的運(yùn)輸協(xié)議和應(yīng)用程序可以訪問(wèn)的住址，像往常一樣。圖 1 說(shuō)明了家鄉(xiāng)代理和記者的單個(gè)節(jié)點(diǎn)的移動(dòng) IPv6 的注冊(cè)過(guò)程。首頁(yè)注冊(cè)包含綁定更新消息的通告新轉(zhuǎn)交地址和綁定確認(rèn)的一條消息，指示成功或失

11、敗的家鄉(xiāng)代理。必須注意防止非法綁定，哪些惡意的節(jié)點(diǎn)可以嘗試模擬或重定向的目的建立基于洪水。移動(dòng)節(jié)點(diǎn)和家鄉(xiāng)代理通常根據(jù)相同的管理和共享憑據(jù)，以引導(dǎo) IPsec 安全關(guān)聯(lián)。首頁(yè)注冊(cè)可以因此被身份驗(yàn)證和加密。記者注冊(cè)允許路由優(yōu)化。它包括傳達(dá)對(duì)應(yīng)的節(jié)點(diǎn)，并響應(yīng)的綁定的確認(rèn)新轉(zhuǎn)交地址的綁定更新消息。這些無(wú)法一般保護(hù)通過(guò) IPsec，不過(guò)，因?yàn)橐苿?dòng)節(jié)點(diǎn)均可能要共享的身份驗(yàn)證憑據(jù)，他們可能在某一時(shí)刻的所有相應(yīng)節(jié)點(diǎn)進(jìn)行溝通，也不是"全局"公鑰基礎(chǔ)結(jié)構(gòu)，可任意對(duì)的節(jié)點(diǎn)，才能投入存在任何時(shí)間很快 。記者注冊(cè)而是通過(guò)身份驗(yàn)證和授權(quán)通過(guò)返回路徑能力的程序，基于非加密的家庭和照顧的地址在移動(dòng)節(jié)點(diǎn)的可訪問(wèn)性的核查。在這兩

12、個(gè)地址可達(dá)憑移動(dòng)節(jié)點(diǎn)，以啟動(dòng)地址之間的綁定。 家庭地址測(cè)試中，移動(dòng)節(jié)點(diǎn)隧道主測(cè)試初始化消息到家鄉(xiāng)代理，將轉(zhuǎn)發(fā)到通信節(jié)點(diǎn)的消息。通信節(jié)點(diǎn)返回到首頁(yè)測(cè)試郵件內(nèi)的家庭住址的不可預(yù)知的家庭關(guān)鍵一代令牌。家鄉(xiāng)代理截獲此消息和隧道它到移動(dòng)節(jié)點(diǎn)。護(hù)理的地址測(cè)試是移動(dòng)節(jié)點(diǎn)和通信節(jié)點(diǎn)之間的直接交流。它包括照顧的測(cè)試初始化消息和照顧的測(cè)試消息具有不可預(yù)知的護(hù)理的關(guān)鍵一代令牌。國(guó)內(nèi)外護(hù)理的關(guān)鍵一代標(biāo)記的知識(shí)證明分別接收數(shù)據(jù)包的家庭住址和照顧的地址，在移動(dòng)節(jié)點(diǎn)的能力。移動(dòng)節(jié)點(diǎn)通過(guò)使用來(lái)自這兩個(gè)標(biāo)記密鑰驗(yàn)證通信節(jié)點(diǎn)的綁定更新消息演示了這方面的知識(shí)。通信節(jié)點(diǎn)使用相同的密鑰進(jìn)行身份驗(yàn)證的最后綁定的確認(rèn)消息。移動(dòng) IPv6

13、 RFC 葉片對(duì)調(diào)度信號(hào)和數(shù)據(jù)包中移動(dòng)節(jié)點(diǎn)的自由。圖 1 顯示了一個(gè)保守的移動(dòng)節(jié)點(diǎn)，等待來(lái)自家鄉(xiāng)代理的綁定的確認(rèn)消息之前它啟動(dòng)的返回路徑能力的過(guò)程。與此相反，樂(lè)觀的移動(dòng)節(jié)點(diǎn)并行執(zhí)行首頁(yè)注冊(cè)和回報(bào)擊潰能力的過(guò)程。樂(lè)觀的移動(dòng)節(jié)點(diǎn)而且開(kāi)始發(fā)送數(shù)據(jù)包到通信節(jié)點(diǎn)等通信節(jié)點(diǎn)的綁定更新消息已在路上，而保守的移動(dòng)節(jié)點(diǎn)接收的確認(rèn)后，才使用的新的護(hù)理的地址。在任一情況下，直到它接收到的綁定更新消息，不知道有新的轉(zhuǎn)交地址的通信節(jié)點(diǎn)。?rst 數(shù)據(jù)包發(fā)送到新的護(hù)理的地址將因此會(huì)送交移動(dòng)大約隨綁定的確認(rèn)消息，假設(shè)這一要求移動(dòng)節(jié)點(diǎn)的節(jié)點(diǎn)。首頁(yè)注冊(cè)失敗的情況下，保守的移動(dòng)節(jié)點(diǎn)避免無(wú)用的返回路徑能力的過(guò)程。他們亦不可能不久后

14、丟失或被拒絕的綁定更新消息發(fā)送的數(shù)據(jù)包的丟失。對(duì)應(yīng)的節(jié)點(diǎn)將丟棄這些安全措施綁定不匹配的面孔的數(shù)據(jù)包。這是額外的切換延遲為代價(jià)的當(dāng)兩次注冊(cè)成功。傳出路由優(yōu)化的包，這是移動(dòng)節(jié)點(diǎn)和家鄉(xiāng)代理加移動(dòng)節(jié)點(diǎn)和通信節(jié)點(diǎn)之間的往返時(shí)間之間的往返時(shí)間。傳入的數(shù)據(jù)包，額外的切換延遲是移動(dòng)節(jié)點(diǎn)和家鄉(xiāng)代理之間的往返時(shí)間。樂(lè)觀的移動(dòng)節(jié)點(diǎn)性能更好，一般情況下。但他們可能白費(fèi)嘗試返回路徑能力過(guò)程或有包損失應(yīng)家庭或代理注冊(cè)失敗。 3 .基于現(xiàn)有條件的解決方法 現(xiàn)有和改善的切換性能的標(biāo)準(zhǔn)切換過(guò)程可以顯著延遲損害質(zhì)量的實(shí)時(shí)應(yīng)用程序，即使路由優(yōu)化設(shè)計(jì)意圖改善建議方法對(duì)這些應(yīng)用程序支持。研究社會(huì)一直在努力減少一些時(shí)候的切換延遲，并

15、取得了多項(xiàng)建議。特別是有前途的是下列方法。 3.1 路由器發(fā)現(xiàn) 更復(fù)雜的調(diào)度路由器中的時(shí)間間隔可以提高路由器發(fā)現(xiàn)對(duì)帶寬消耗和限度地優(yōu)化。加快融入允許移動(dòng)節(jié)點(diǎn)請(qǐng)求立即的廣告。當(dāng)移動(dòng)節(jié)點(diǎn)的鏈路層可以指示在網(wǎng)絡(luò)連接中的更改時(shí)，這非常有用?；阪溌飞系穆酚善鞯逆溄颖镜氐刂泛驼?qǐng)求的來(lái)源地址，每個(gè)路由器自主計(jì)算動(dòng)態(tài)的排名，指示路由器應(yīng)響應(yīng)立即和可能的其它路由器應(yīng)該不久發(fā)送更多的廣告?？焖俾酚善靼l(fā)現(xiàn)建議接入點(diǎn)重播高速緩存的路由器廣告郵件，一旦相關(guān)聯(lián)的節(jié)點(diǎn)。這種網(wǎng)絡(luò)一側(cè)的鏈路層支持消除了在移動(dòng)節(jié)點(diǎn)的鏈路層觸發(fā)器的要求。 3.2 地址配置 為了避免手關(guān)閉造成的延誤標(biāo)準(zhǔn)重復(fù)地址檢測(cè)，取得了地址 不同的提

16、案。IPv6 工作組內(nèi)的 IETF 正在樂(lè)觀重復(fù)地址檢測(cè) ，它允許有限使用可能重復(fù)的 IP 地址。移動(dòng)節(jié)點(diǎn)暫時(shí)更改的規(guī)則，他們做了 IPv6 鄰居發(fā)現(xiàn)，以免污染可能是非法的地址解析信息與其他節(jié)點(diǎn)的鄰居高速緩存的信號(hào)。先進(jìn)的重復(fù)地址檢測(cè)，路由器生成，他們?cè)俜峙浣o移動(dòng)節(jié)點(diǎn)的唯一地址的池。重復(fù)地址檢測(cè)執(zhí)行地址上提前這樣，移動(dòng)節(jié)點(diǎn)可以配置他們立即無(wú)需驗(yàn)證自己的唯一性。 3.3 運(yùn)動(dòng)檢測(cè) DNA 內(nèi) IETF 工作組處理慢運(yùn)動(dòng)檢測(cè)的兩種互補(bǔ)的方法的問(wèn)題。前綴的完整列表協(xié)議適用于路由器。移動(dòng)節(jié)點(diǎn)維護(hù)學(xué)術(shù)上鏈接前綴，可能獲得多個(gè)路由器通告消息接收的列表。列表中已經(jīng)成熟了一會(huì)兒后，移動(dòng)節(jié)點(diǎn)可以假定更改

17、IP 連接高概率時(shí)新收到的廣告僅包含列表中沒(méi)有的前綴。這種預(yù)測(cè)基于可能不完整的信息，所以移動(dòng)節(jié)點(diǎn)可能會(huì)在沒(méi)有實(shí)際發(fā)生時(shí)，甚至斷言運(yùn)動(dòng)。DNA 協(xié)議使用加快融入及時(shí)傳輸?shù)恼?qǐng)求路由器廣告郵件。路由器選擇某些前綴作為鏈接標(biāo)識(shí)符，并為此所顯示的所有傳播廣告中。這允許移動(dòng)節(jié)點(diǎn)，可靠地檢測(cè)中基于單個(gè)廣告的 IP 連接的更改。另外，移動(dòng)節(jié)點(diǎn)可以顯式檢查路由器征集廣告交換的一部分用于前的鏈路層切換，因此稱為一個(gè)里程碑，網(wǎng)絡(luò) pre?x 是否仍有效的可能是新的鏈接。DNA 協(xié)議作為鏈接與舊式的路由器的回退機(jī)制集成了 前綴的完整列表。 3.4 移動(dòng) IPv6 優(yōu)化許多移動(dòng) IPv6 優(yōu)化減少路由優(yōu)化的切換延

18、遲，通過(guò)修改程序的返回路徑的能力。早期綁定更新和基于信用的授權(quán)的組合達(dá)到這一點(diǎn)，對(duì)純粹的端到端的基礎(chǔ)，具有以下四個(gè)組成優(yōu)化： 1。 主動(dòng)家庭地址測(cè)試： 移動(dòng)節(jié)點(diǎn)主動(dòng)的家庭地址測(cè)試期間獲取未來(lái)的切換回家的注冊(cè)機(jī)里的標(biāo)記。這關(guān)鍵的切換期間保存通過(guò)家鄉(xiāng)代理可能長(zhǎng)的往返行程。移動(dòng)節(jié)點(diǎn)可以調(diào)用只是時(shí)間的基礎(chǔ)上積極家庭地址測(cè)試，如果其鏈路層提供指示即將切換，觸發(fā)器或定期每當(dāng)最近取得的最大主關(guān)鍵一代令牌將過(guò)期。2.同時(shí)照顧的地址測(cè)試： 數(shù)據(jù)包可以已交換，在有限的程度上，通過(guò)新的護(hù)理的地址，而在該轉(zhuǎn)交地址移動(dòng)節(jié)點(diǎn)的可達(dá)性正在北朝鮮。3.試綁定： 移動(dòng)節(jié)點(diǎn)注冊(cè)其家鄉(xiāng)地址與地址未經(jīng)核實(shí)的護(hù)理的暫定綁定通過(guò)交換與通

19、信節(jié)點(diǎn)的早期綁定更新和早期綁定的確認(rèn)消息。僅以家庭的關(guān)鍵一代令牌索取最近的主動(dòng)家庭地址測(cè)試，從而促進(jìn)后續(xù)的并行的護(hù)理的地址測(cè)試情況下，消息進(jìn)行身份驗(yàn)證。一旦移動(dòng)已執(zhí)行并行的護(hù)理的地址測(cè)試，它對(duì)標(biāo)準(zhǔn)的綁定更新消息進(jìn)行身份驗(yàn)證，并與通信節(jié)點(diǎn)注冊(cè)北朝鮮轉(zhuǎn)交地址。 4.家庭和記者注冊(cè)的并行 移動(dòng) IPv6規(guī)格不允許綁定更新消息發(fā)送到對(duì)應(yīng)的節(jié)點(diǎn)之前確認(rèn)收到來(lái)自家鄉(xiāng)代理, 移動(dòng)節(jié)點(diǎn)。如果結(jié)合的主動(dòng)家庭地址測(cè)試和并發(fā)護(hù)理的地址測(cè)試隱藏程序的返回路徑能力滯后時(shí)間，這就會(huì)成為性能問(wèn)題。移動(dòng) IPv6 的規(guī)則因此放寬，以允許移動(dòng)節(jié)點(diǎn)，早期綁定更新的訊息，首頁(yè)注冊(cè)時(shí)仍然掛起。著名安全指引禁止向的可達(dá)性尚未北朝

20、鮮轉(zhuǎn)交地址發(fā)送數(shù)據(jù)包的通信節(jié)點(diǎn)。這是防范惡意，否則可能誘供水請(qǐng)求數(shù)據(jù)包的第三方對(duì)應(yīng)的節(jié)點(diǎn)的節(jié)點(diǎn)。這種基于重定向的洪水攻擊的吸引力是工藝擴(kuò)大的潛力。例如，攻擊者可以完成初始的 TCP 握手，自己地址 （或家庭住址，這件事），通過(guò)大量大 128gb 下載，然后將排放重定向到其受害者的地址。攻擊者可能，并會(huì)，以基于它在初始握手期間學(xué)到的序列號(hào)的受害者的名義欺騙確認(rèn)。但確認(rèn)將小比作通信節(jié)點(diǎn)生成的數(shù)據(jù)段?；谛庞玫氖跈?quán)防止基于重定向的放大的洪水攻擊，但可以通過(guò)為核實(shí)轉(zhuǎn)交地址的雙向通信。通信節(jié)點(diǎn)維護(hù)一個(gè)字節(jié)計(jì)數(shù)器的移動(dòng)節(jié)點(diǎn)，也稱為移動(dòng)節(jié)點(diǎn)的信貸，從移動(dòng)節(jié)點(diǎn)接收的數(shù)據(jù)量的增加而減少發(fā)送到移動(dòng)節(jié)點(diǎn)的轉(zhuǎn)交地址是

21、未核實(shí)的數(shù)據(jù)量。指數(shù)老化保證現(xiàn)有信貸表示只最近收到移動(dòng)節(jié)點(diǎn)的數(shù)據(jù)。當(dāng)通信節(jié)點(diǎn)的移動(dòng)節(jié)點(diǎn)的數(shù)據(jù)包時(shí)，發(fā)送至轉(zhuǎn)交地址如果地址是北朝鮮，或者該地址是未核實(shí)，但數(shù)據(jù)包的大小不超過(guò)當(dāng)前可用的信貸。否則為通信節(jié)點(diǎn)可能丟棄數(shù)據(jù)包、 緩沖它直到轉(zhuǎn) 交地址變已查清，或?qū)⑵浒l(fā)送給家鄉(xiāng)的地址。其他路線優(yōu)化增強(qiáng)功能需要某種形式的預(yù)： 端節(jié)點(diǎn)共享密鑰或安全關(guān)聯(lián)，更多的效率，引導(dǎo)的憑據(jù)，并加密的身份驗(yàn)證可以取代家庭地址測(cè)試。這兩項(xiàng)建議目前正在討論中，IETF，預(yù)配置與共享、 秘密身份驗(yàn)證密鑰的移動(dòng)節(jié)點(diǎn)和對(duì)應(yīng)的節(jié)點(diǎn)。使用 IPsec 和互聯(lián)網(wǎng)密鑰交換協(xié)議。這些技術(shù)患可擴(kuò)展性問(wèn)題，但是，鑒于端節(jié)點(diǎn)必須設(shè)置使用成對(duì)的憑據(jù)

22、。此外，技術(shù)都提供了核查的移動(dòng)節(jié)點(diǎn)的可訪問(wèn)性，所以都不能從技術(shù)上講沒(méi)有照顧的地址測(cè)試。端節(jié)點(diǎn)對(duì)等方的可訪問(wèn)性的信任并可進(jìn)一步忽略照顧的地址測(cè)試，，但這種信任是在很多重要的商業(yè)模式中不可用。例如，移動(dòng)電話運(yùn)營(yíng)商可能能夠用秘密身份驗(yàn)證密鑰，配置訂閱服務(wù)器，但可能無(wú)法償還所有訂閱服務(wù)器使用這些注冊(cè)表項(xiàng)，以可靠的方式。移動(dòng) IPv6 優(yōu)化的另一家基于移動(dòng)節(jié)點(diǎn)的訪問(wèn)網(wǎng)絡(luò)中的路由器支持。在快速切換的移動(dòng) IPv6正在部署，移動(dòng)節(jié)點(diǎn)可以請(qǐng)求其當(dāng)前的默認(rèn)路由器建立雙向隧道到一個(gè)新的護(hù)理的地址。這同時(shí)允許暫時(shí)溝通通過(guò)其舊的轉(zhuǎn)交地址后切換，和注冊(cè)新的照顧其家鄉(xiāng)代理地址的移動(dòng)節(jié)點(diǎn)和對(duì)應(yīng)的節(jié)點(diǎn)。代理路由器發(fā)現(xiàn)和輔助的

23、地址的幫助，移動(dòng)節(jié)點(diǎn)可能會(huì)要求隧道之前切換，只要它可以預(yù)測(cè)變動(dòng)。附加功能優(yōu)化的意外的鏈接中斷的情況下無(wú)功的切換管理。與此相反，媒體獨(dú)立預(yù)身份驗(yàn)證使用舊的轉(zhuǎn)交地址和一個(gè)新的默認(rèn)路由器之間的雙向隧道。移動(dòng)節(jié)點(diǎn)分配新轉(zhuǎn)交地址從遠(yuǎn)程和影響家庭和記者注冊(cè)之前，它將更改鏈接。如果相鄰單元格之間的重疊是充分的大允許切換準(zhǔn)備工作及時(shí)完成，化的這種做法是類(lèi)似的快速切換。然而，細(xì)胞重疊在哪里小相對(duì)于節(jié)點(diǎn)的速度，推遲全球后切換到一個(gè)階段信號(hào)是有利，因?yàn)闊o(wú)線信號(hào)質(zhì)量則通常更高和更持久。媒體獨(dú)立預(yù)身份驗(yàn)證的力量是進(jìn)行預(yù)身份驗(yàn)證切換之前，新的網(wǎng)絡(luò)移動(dòng)節(jié)點(diǎn)的能力。分層移動(dòng) IPv6可以綁定到一個(gè)更穩(wěn)定的區(qū)域護(hù)理的地址的其當(dāng)

24、前的鏈路上照顧的地址從移動(dòng)錨點(diǎn)網(wǎng)絡(luò)的移動(dòng)節(jié)點(diǎn)位于其他位置訪問(wèn)域中。移動(dòng)節(jié)點(diǎn)發(fā)送和接收數(shù)據(jù)包通過(guò)雙向隧道本身和移動(dòng)錨點(diǎn)之間的區(qū)域護(hù)理的地址。它對(duì)應(yīng)的節(jié)點(diǎn)，家鄉(xiāng)代理注冊(cè)的區(qū)域轉(zhuǎn)交地址，并更新移動(dòng)錨點(diǎn)，每當(dāng)運(yùn)動(dòng)后的變化及其對(duì)鏈接的地址。運(yùn)動(dòng)可以使隱藏從家鄉(xiāng)代理和對(duì)應(yīng)的節(jié)點(diǎn)，只要移動(dòng)節(jié)點(diǎn)在同一移動(dòng)錨點(diǎn)領(lǐng)域內(nèi)的山巔。 5. 結(jié)論 高效端到端切換需要優(yōu)化，不僅為移動(dòng)性協(xié)議，路由器發(fā)現(xiàn)、地址和運(yùn)動(dòng)檢測(cè)。在今天的 IPv6 協(xié)議標(biāo)準(zhǔn)，探討了自己的缺點(diǎn)和各種現(xiàn)有的優(yōu)化，審查這些交互，以及如何可以將它們合并到一個(gè)完整和高效的移動(dòng)解決方案。它是必須認(rèn)識(shí)到明天的流動(dòng)性支持的基礎(chǔ)是今天提交。這尤其適用于路徑的優(yōu)化，

25、并需要從兩個(gè)同行的支持，因此取決于相應(yīng)的節(jié)點(diǎn)中實(shí)現(xiàn)了堅(jiān)實(shí)的基礎(chǔ)。因此應(yīng)包括路由優(yōu)化功能早期新興 IPv6 堆棧。增強(qiáng)功能還必須訪問(wèn)路由器，其響應(yīng)能力至關(guān)重要的高效IPv6 和運(yùn)動(dòng)檢測(cè)到他們的方式。越早的必要優(yōu)化的一組被廣泛接受這套將最終的可能性會(huì)無(wú)處不支持。 A Comprehensive and Efficient Handoff Procedure for IPv6 Mobility Support Abstract Handoff performance with Mobile IPv6 Route Optimization strongly depends on

26、the ef?ciency of IP-layer autocon?guration mechanisms as well as the ?exibility of mobile nodes to schedule and parallelize their signaling. This paper provides a comprehensive analysis of the handoff performance with the standard IPv6 protocol suite and Mobile IPv6, and it identi?es several sources

27、 for delay. While some of the delays are already well known, an optimized and widely applicable handoff approach is yet to be found. The paper hence proceeds to discuss existing and new optimization proposals, some of which are currently under standardization within the IETF, and elaborates how a co

28、mbination of those can signi?cantly improve handoff experience. 1.Introduction As Internet-based services pervade daily life more and more, users increasingly desire them to be accessible at any place and any time. At the same time grows the importance of real-time communications [19] such as au

29、dio and video streaming, IP telephony, or video conferencing. Realtime communications are highly delay-sensitive and exhibit a susceptibility to long propagation latencies and handoff delays. Ef?cient mobility support was hence amongst the primary objectives during the design of the next-generation

30、Internet, and a mode for Route Optimization was incorporated into the Mobile IPv6 [9] mobility protocol. Route Optimization allows peers to communicate via a direct path.This complements the classic approach of routing a mobile node’s traf?c through a stationary proxy, its home agent. While Route O

31、ptimization mitigates the problem withpropagation latencies, handoff delays are still substantial enough to effectively preclude meaningful real-time support [2, 12, 13]. In fact, handoff delays in a standard IPv6 deployment are in the order of seconds. This is not only due to Mobile IPv6, but also

32、affects standard IPv6 con?guration and movement-detection mechanisms [15, 24].Very fortunately, a multitude of optimization techniques[3, 5, 10, 14, 18] have recently been put forth to streamline individual handoff-related activities. Measurement data is typically available to corroborate the bene?t

33、s of any speci?c technique. But a study of how well the optimizations integrate has so far been largely neglected [1]. This paper examines the challenges with mobility from a higher perspective: It explains the overall handoff procedure in a standard IPv6 deployment from an IP layer’s perspective a

34、nd analyzes inhowfar it falls short of expectations. Since the results strongly advise optimization, the paper proceeds to explore promising existing and new proposals that have recently gained momentum in both in the Internet Engineering Task Force (IETF) and the academic research community. The op

35、timizations are also evaluated with respect to their interactions. The paper ?nally proposes an integrated solution for improved handoff performance. 2. Standard Handoff Procedure A mobile node undergoes an IP-layer handoff, or simply a handoff, when it changes IP connectivity. This begins with

36、a change in link-layer attachment, also referred to as a link-layer handoff, and is followed by the discovery of newrouters, address con?guration, movement detection, and ?nally Mobile IPv6 registrations. Figure 1 illustrates these handoff steps, which are separately discussed next. 2.1 Router Disc

37、overy A mobile node learns about local routers and on-link pre?xes during router discovery. This process is facilitated through Router Advertisement messages, which routers multicast to link-local nodes on a loosely periodic basis. The IPv6 Neighbor Discovery RFC [16] states that unsolicited Route

38、r Advertisement messages are to be sent in random intervals of between 3 and 4 seconds at least and between 1350 and 1800 seconds at most. Since these conservative limits are tailored towards stationary nodes and fail to meaningfully support mobility, the Mobile IPv6 RFC decreases the lower bound to

39、 one beacon every 30 to 70 milliseconds. This reduces the mean time between successiveadvertisements to 50 milliseconds so that a mobile node can expect to receive the ?rst post-handoff advertisement after 25 milliseconds. On the other hand, high frequencies for multicast advertisements may be an is

40、sue in low-bandwidth,wide-area networks, where many users may not frequently leave the geographic area covered by the same IP subnet. 2.2 Address Con?guration A mobile node con?gures a new global IP address upon receipt of a Router Advertisement message with an unknown pre?x. This typically happen

41、s in compliance with Stateless Address Autocon?guration [22]: The mobile node chooses an interface identi?er, either randomly or based on the interface’s MAC address, and prepends to this the obtained pre?x. It then sends aMulticast Listener Report message [4] to subscribe to the solicited-node mult

42、icast group corresponding to the new address. If the Router Advertisement message was a multicast transmission, which usually is the case, the Multicast Listener Report message is de-layed by up to 1 second to desynchronize with neighboring nodes that may be reacting to the same advertisement. The m

43、obile node then runs the Duplicate Address Detection protocol to verify whether the new address is unique: It transmits a Neighbor Solicitation message for the address and, if no responses are received within a period of 1 second, assigns the address to the interface. The total con?guration period h

44、ence ranges between 1 and 2 seconds if the address is unique. The probability for an IPv6 address to already be in use by another node is small enough to make it negligible. Even though the link-local address keeps its pre?x during handoff, the mobile node must still re-verify uniqueness of this add

45、ress when IP connectivity changes, because a node on the new link may already be using the same linklocal address. This is done through another run of Duplicate Address Detection. Since only movement detection can establish whether IP connectivity has changed, re-veri?cation of the link-local addre

46、ss typically begins after movement detection. This is not shown in ?gure 1, however, given that the availability of the link-local address does not in?uence the schedule for other handoff-related activities. 2.3 Movement Detection Mobile nodes implement movement detection to recog- nize chang

47、es in IP connectivity. Such a change implies that a mobile node chooses a new default router, invalidates stale global addresses, re-veri?es uniqueness of its link-local address, and initiates Mobile IPv6 registrations. Movement detection relies on analyzing the on-link pre?xes advertised in Router

48、Advertisement messages and possibly also probing reachability of routers considered off-link. When the pre?xes in use by the mobile node are no longer seen to be advertised, but new pre?xes show up instead, the mobile node typically decides that it has moved to a different network. On the other hand

49、, received pre?xes may also indicate that IP connectivity did not change in spite of a linklayer handoff, e.g., when the mobile node switches access points that connect to the same subnet. Movement detection is complicated by the fact that Router Advertisement messages may include incompletesets of

50、pre?xes. Reception of a single advertisement is therefore usually insuf?cient to decide whether IP connectivity has changed. It is also generally impossible to determine when an advertisement should have been received,but did not appear, due to the lack of a guaranteed advertisement interval. The Mo

51、bile IPv6 RFC helps in this respect in that it introduces an Advertisement Interval option for Router Advertisement messages. Routers use this option to indicate an upper bound on their beaconing periods. Wherethis is as low as 70 milliseconds (cf. section 2.1), an extra 20 milliseconds are added in

52、 order to account for scheduling granularities in mobile nodes and routers. Mobile nodes then expect Router Advertisement messages to arrive in intervals of at most 90 milliseconds.Nevertheless, the absence of a single expected advertisement still does not imply a change in IP connectivity given the

53、 potential for packet loss. Three missing advertisements indicate movement more reliably. A decision can then be made at most 270 milliseconds after the last advertisement was received from the old default router. The actual linklayer handoff may occur up to 70 milliseconds later, so movement detect

54、ion can take any time between 200 and 270 milliseconds. On average, the period between reception of the last advertisement from the old default router and the link-layer handoff is 25 milliseconds, yielding a mean movement-detection delay of 245 milliseconds. 2.4 Mobile IPv6 Registration After add

55、ress con?guration and movement detection, the mobile node selects one of its new global addresses to be registered as a care-of address with its home agent and correspondent nodes. This establishes a binding between the care-of address and the mobile node’s home address, which has a pre?x from the h

56、ome agent’s network and remains stable across movements. The home address is used at stack layers above IP as part of end-point identi?cation. Data packets that a mobile node exchanges with a peer have the care-of address in the IP header and the home address in an IPv6 extension header while on the

57、 wire. Both end nodes swap the addresses when a packet traverses the IP layer so that transport protocols and applications can access the home address as usual. Figure 1 illustrates the Mobile IPv6 registration procedure for the home agent and a single correspondent node. The home registration con

58、sists of a Binding Update message which noti?es the home agent of the new care-of address, and a Binding Acknowledgment message indicating success or failure. Care must be taken to preclude illegitimate bindings [17], which malicious nodes could attempt to establish for the purpose of impersonation

59、or redirectionbased ?ooding. The mobile node and the home agent arebtypically under the same administration and pre-share credentials to bootstrap an IPsec security association. The home registration can so be authenticated and encrypted. The correspondent registration permits Route Optimization. I

60、t includes a Binding Update message that conveys the new care-of address to the correspondent node, and a responding Binding Acknowledgment message2. Thesecannot generally be protected through IPsec, however, because mobile nodes are neither likely to share authentication credentials with all corres

61、pondent nodes they may at some point communicate with, nor is a ”global” public-key infrastructure, available for arbitrary pairs of nodes, expected to come into existence any time soon [17]. Correspondent registrations are instead authenticated and authorized through a return-routability procedure,

62、 based on non-cryptographic veri?cation of a mobile node’s reachability at the home and care-of addresses. Reachability at both addresses entitles the mobile node to initiate a binding between the addresses. For the home-address test, the mobile node tunnels a Home Test Init message to the home age

63、nt, which forwards the message to the correspondent node. The correspondent node returns an unpredictable home keygen token to the home address within a Home Test message. The home agent intercepts this message and tunnels it to the mobile node. The care-of-address test is a direct exchange between

64、the mobile node and the correspondent node. It consists of a Care-of Test Init message and a Care-of Test message with an unpredictable care-of keygen token. Knowledge of the home and care-of keygen tokens proves the mobile node’s ability to receive packets at the home address and care-ofaddress, re

65、spectively. The mobile node demonstrates this knowledge by authenticating the Binding Update message for the correspondent node with a key derived from both tokens. The correspondent node uses the same key to authenticate the ?nal Binding Acknowledgment message.TheMobile IPv6 RFC leaves mobile node

66、s liberties withn respect to scheduling signaling and data packets. Figure1 shows a conservative mobile node, which waits for the Binding Acknowledgment message from the home agent before it initiates the return-routability procedure. In contrast, an optimistic mobile node executes the home registration and the return-routability procedure in parallel. An optimistic mobile node furthermore starts sending packets to the correspondent node as soon as the Binding Update message for the correspon