Peering

在計算機網絡中，Peering（譯為：對等互連^[1]^[2]、互聯^[3]、對等操作^[4]、對等互聯^[5]，等。後述使用「對等互連」作為代詞）是獨立管理的互聯網網絡自願互聯，用於為每個網絡的「下游」用戶之間交換流量。對等互連是免結算費的，也稱為「計費和保留賬單（bill-and-keep）」或者「發送者保留全部（sender keeps all）」，這意味着任何一方都不需要向另一方支付與流量交換相關的費用；相反，每個網絡公司都從自己的客戶那裡獲得並保留相應的流量使用收入。

兩個或者多個網絡相互對等互連需要通過網絡間物理互聯，通過邊界網關協議（BGP）相互交換路由信息，也會通過一些行業默認的規範，甚至更罕見的情況（0.07%），使用正式的合同文件，來約束交互路由行為。^[6]^[7]

在0.02%的情況下，「對等互連」可能會涉及某些需要結算的情況，由於這些情況可能造成歧義，因此「免結算對等互連（settlement-free peering）」專門用於準確描述正常情況的免費對等互連情況。^[8]

實現機理

互聯網是由一組獨立且不同的網絡集合（自治系統）而成，每個網絡都包含一組全球唯一的IP地址和唯一的全球BGP路由策略。

自治系統之間的互聯關係恰好有兩種方式：

Peering（對等互連）：兩個網絡之間的用戶可以自由交換流量，並實現互惠互利。^[9]
Transit（轉接）：一個網絡向另一個網絡支付費用以用於獲得訪問互聯網。^[9]

因此，為了使網絡能夠達到互聯網上任何特定網絡，它必須：

售賣transit服務給其他網絡或者這個網絡的一系列經銷商。（作為「客戶」）
與其他網絡或有買入transit服務的網絡建立Peering關係。
向其他網絡購買transit服務（這些網絡和其他網絡有進行Peering關係）。

互聯網基於全球或端到端可達性原則，這意味着任何互聯網用戶都可以透明地與任何其他互聯網用戶交換流量。因此，當且僅當網絡購買了Transit，或者與同樣不購買Transit的每個其他網絡進行對等Peering（它們一起構成「默認自由區域（英語：Default-free zone）（default free zone，DFZ））時，該網絡才連接到互聯網。

用於對等互連的物理互連

一種通過第一層（物理層）或者第二層（數據鏈路層）方式實現互聯的互聯網交換中心

一種通過第三層（網絡層）方式實現互聯的互聯網交換中心

用於對等互連的物理連接方式分為兩種類型：

公共對等互連——多方利用類似以太網交換機的共享交換結構來進行互聯。^[9]
私有對等互連——雙方通過點對點鏈路進行互聯。^[9]

參見

參考資料

^ 直接对等互连概览. Google Cloud. [2024-05-12]. （原始內容存檔於2024-05-12）（中文（中國大陸））.
^ 对等互联政策. retn.net. [2024-05-12]. （原始內容存檔於2024-05-02）（cn）.
^ 電信服務資費管制監理案. 國家通訊傳播委員會. 2017-04-18 [2024-05-12]. （原始內容存檔於2024-05-02）.
^ 术语在线. www.termonline.cn. [2024-05-12]. （原始內容存檔於2024-05-02）.
^ ISP免费对等互联策略. doi:10.16511/j.cnki.qhdxxb.2013.11.021.
^ Woodcock, Bill; Adhikari, Vijay. Survey of Characteristics of Internet Carrier Interconnection Agreements (PDF). Packet Clearing House. 2011-05-02 [2011-05-05]. （原始內容 (PDF)存檔於2015-06-10）.
^ Woodcock, Bill; Frigino, Marco. Survey of Characteristics of Internet Carrier Interconnection Agreements (PDF). Packet Clearing House. 2016-11-21 [2021-05-28]. （原始內容存檔 (PDF)於2021-07-07）. Of the total analyzed agreements, 1,347 (0.07%) were formalized in written contracts. This is down from 0.49% in 2011. The remaining 1,934,166 (99.93%) were 「handshake」 agreements in which the parties agreed to informal or commonly understood terms without creating a written document.
^ Woodcock, Bill; Frigino, Marco. Survey of Characteristics of Internet Carrier Interconnection Agreements (PDF). Packet Clearing House. 2016-11-21 [2021-05-28]. （原始內容存檔 (PDF)於2021-07-07）. Of the agreements we analyzed, 1,935,111 (99.98%) had symmetric terms, in which each party gave and received the same conditions as the other. Only 403 (0.02%) had asymmetric terms, in which the parties gave and received conditions with specifically defined differences, and these exceptions were down from 0.27% in 2011. Typical examples of asymmetric agreements are ones in which one of the parties compensates the other for routes that it would not otherwise receive (sometimes called 「paid peering」 or 「on-net routes」), or in which one party is required to meet terms or requirements imposed by the other (「minimum peering requirements」), often concerning volume of traffic or number or geographic distribution of interconnection locations.
^ ^9.0 ^9.1 ^9.2 ^9.3 IP Transit vs Peering: What’s the Difference?. Kentipedia. 2023-04-28 [2024-05-12]. （原始內容存檔於2024-05-24）（英語）.

外部連結

[1] 直接对等互连概览. Google Cloud. [2024-05-12]. （原始內容存檔於2024-05-12）（中文（中國大陸））.

[2] 对等互联政策. retn.net. [2024-05-12]. （原始內容存檔於2024-05-02）（cn）.

[3] 電信服務資費管制監理案. 國家通訊傳播委員會. 2017-04-18 [2024-05-12]. （原始內容存檔於2024-05-02）.

[4] 术语在线. www.termonline.cn. [2024-05-12]. （原始內容存檔於2024-05-02）.

[5] ISP免费对等互联策略. doi:10.16511/j.cnki.qhdxxb.2013.11.021.

[PCH2011survey-6] Woodcock, Bill; Adhikari, Vijay. Survey of Characteristics of Internet Carrier Interconnection Agreements (PDF). Packet Clearing House. 2011-05-02 [2011-05-05]. （原始內容 (PDF)存檔於2015-06-10）.

[PCH2016survey-1-7] Woodcock, Bill; Frigino, Marco. Survey of Characteristics of Internet Carrier Interconnection Agreements (PDF). Packet Clearing House. 2016-11-21 [2021-05-28]. （原始內容存檔 (PDF)於2021-07-07）. Of the total analyzed agreements, 1,347 (0.07%) were formalized in written contracts. This is down from 0.49% in 2011. The remaining 1,934,166 (99.93%) were 「handshake」 agreements in which the parties agreed to informal or commonly understood terms without creating a written document.

[PCH2016survey-2-8] Woodcock, Bill; Frigino, Marco. Survey of Characteristics of Internet Carrier Interconnection Agreements (PDF). Packet Clearing House. 2016-11-21 [2021-05-28]. （原始內容存檔 (PDF)於2021-07-07）. Of the agreements we analyzed, 1,935,111 (99.98%) had symmetric terms, in which each party gave and received the same conditions as the other. Only 403 (0.02%) had asymmetric terms, in which the parties gave and received conditions with specifically defined differences, and these exceptions were down from 0.27% in 2011. Typical examples of asymmetric agreements are ones in which one of the parties compensates the other for routes that it would not otherwise receive (sometimes called 「paid peering」 or 「on-net routes」), or in which one party is required to meet terms or requirements imposed by the other (「minimum peering requirements」), often concerning volume of traffic or number or geographic distribution of interconnection locations.

[:0-9] 9.0 ^9.1 ^9.2 ^9.3 IP Transit vs Peering: What’s the Difference?. Kentipedia. 2023-04-28 [2024-05-12]. （原始內容存檔於2024-05-24）（英語）.

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