本發(fā)明屬于網(wǎng)絡(luò)通信
技術(shù)領(lǐng)域：
，涉及一種數(shù)據(jù)傳輸系統(tǒng)，具體的說(shuō)，涉及一種應(yīng)用于軌道列車寬帶網(wǎng)絡(luò)數(shù)據(jù)傳輸?shù)南到y(tǒng)及方法。
背景技術(shù)：
：列車通訊數(shù)據(jù)量劇增，而傳統(tǒng)的列車總線無(wú)法滿足大數(shù)據(jù)量傳輸需求。工業(yè)以太網(wǎng)具有穩(wěn)定性高、通信速率高等優(yōu)點(diǎn)，隨著工業(yè)以太網(wǎng)技術(shù)的發(fā)展，基于工業(yè)以太網(wǎng)的列車通信網(wǎng)絡(luò)因其組網(wǎng)拓?fù)浣Y(jié)構(gòu)靈活，傳輸速度高等優(yōu)點(diǎn)，已成為列車通信網(wǎng)絡(luò)發(fā)展的新方向。過(guò)程數(shù)據(jù)對(duì)傳輸有相對(duì)嚴(yán)格的定時(shí)，軌道列車網(wǎng)絡(luò)中，過(guò)程數(shù)據(jù)傳輸對(duì)實(shí)時(shí)性、可靠性要求較高，在現(xiàn)有方案中，大多采用在終端應(yīng)用層，賦予過(guò)程數(shù)據(jù)較高優(yōu)先級(jí)，并在規(guī)定時(shí)間內(nèi)發(fā)送，來(lái)確保過(guò)程數(shù)據(jù)的實(shí)時(shí)性。這種方案存在以下不足：(1)網(wǎng)絡(luò)帶寬利用率最多只有30％，造成帶寬浪費(fèi)；(2)存在端到端的延遲和抖動(dòng)，需要安全邊際；(3)為在及時(shí)、快速的數(shù)據(jù)傳輸過(guò)程中保證數(shù)據(jù)傳輸?shù)木_度和穩(wěn)定性，需要在數(shù)據(jù)延時(shí)，抖動(dòng)和帶寬間取舍。技術(shù)實(shí)現(xiàn)要素：本發(fā)明的目的在于針對(duì)現(xiàn)有技術(shù)的不足，提供一種可減少實(shí)時(shí)數(shù)據(jù)傳輸延時(shí)和抖動(dòng)的軌道列車寬帶網(wǎng)絡(luò)實(shí)時(shí)性數(shù)據(jù)傳輸系統(tǒng)及方法。本發(fā)明的技術(shù)方案為：軌道列車寬帶網(wǎng)絡(luò)實(shí)時(shí)性數(shù)據(jù)傳輸系統(tǒng)，包括數(shù)據(jù)終端設(shè)備和數(shù)據(jù)交換設(shè)備；數(shù)據(jù)經(jīng)一數(shù)據(jù)終端設(shè)備發(fā)出，經(jīng)在數(shù)據(jù)交換設(shè)備中轉(zhuǎn)并最終到達(dá)另一數(shù)據(jù)終端設(shè)備；數(shù)據(jù)終端設(shè)備或數(shù)據(jù)交換設(shè)備執(zhí)行以下功能模塊：同步時(shí)間戳模塊：記錄數(shù)據(jù)到達(dá)設(shè)備的時(shí)間；相應(yīng)的，若同步時(shí)間戳模塊配置在數(shù)據(jù)終端設(shè)備，則記錄的為數(shù)據(jù)到達(dá)數(shù)據(jù)終端設(shè)備的時(shí)間，若同步時(shí)間戳模塊配置在數(shù)據(jù)交換設(shè)備，則記錄的為數(shù)據(jù)到達(dá)數(shù)據(jù)交換設(shè)備的時(shí)間；所述數(shù)據(jù)交換設(shè)備執(zhí)行以下功能模塊：數(shù)據(jù)校驗(yàn)?zāi)K：用于完成數(shù)據(jù)長(zhǎng)度和CRC校驗(yàn)；數(shù)據(jù)分類模塊：在數(shù)據(jù)流中識(shí)別出實(shí)時(shí)數(shù)據(jù)，并轉(zhuǎn)發(fā)；數(shù)據(jù)處理模塊：包括實(shí)時(shí)數(shù)據(jù)處理模塊：用于接收數(shù)據(jù)分類模塊識(shí)別出的實(shí)時(shí)數(shù)據(jù)，并轉(zhuǎn)發(fā)。優(yōu)選的是：所述數(shù)據(jù)分類模塊還用于從數(shù)據(jù)流中識(shí)別出時(shí)間同步數(shù)據(jù)、除時(shí)間同步數(shù)據(jù)和實(shí)時(shí)數(shù)據(jù)以外的傳統(tǒng)以太網(wǎng)數(shù)據(jù)，并轉(zhuǎn)發(fā)；所述數(shù)據(jù)處理模塊還包括：同步數(shù)據(jù)處理模塊：用于接收數(shù)據(jù)分類模塊轉(zhuǎn)發(fā)的時(shí)間同步數(shù)據(jù)并轉(zhuǎn)發(fā)；傳統(tǒng)以太網(wǎng)數(shù)據(jù)處理模塊：用于接收數(shù)據(jù)分類模塊轉(zhuǎn)發(fā)的轉(zhuǎn)發(fā)傳統(tǒng)以太網(wǎng)數(shù)據(jù)并轉(zhuǎn)發(fā)；軌道列車寬帶網(wǎng)絡(luò)實(shí)時(shí)性數(shù)據(jù)傳輸系統(tǒng)還包括配置于數(shù)據(jù)交換設(shè)備中的：優(yōu)先級(jí)裁決模塊：用于接收同步數(shù)據(jù)處理模塊和以太網(wǎng)數(shù)據(jù)處理模塊轉(zhuǎn)發(fā)的數(shù)據(jù)，裁斷接收到時(shí)間同步數(shù)據(jù)或以太網(wǎng)數(shù)據(jù)的優(yōu)先級(jí)，并根據(jù)數(shù)據(jù)優(yōu)先級(jí)將數(shù)據(jù)轉(zhuǎn)發(fā)；多路選擇模塊：用于接收優(yōu)先級(jí)裁決模塊及實(shí)時(shí)數(shù)據(jù)處理模塊轉(zhuǎn)發(fā)的數(shù)據(jù)，裁斷接收到數(shù)據(jù)的優(yōu)先級(jí)，并根據(jù)數(shù)據(jù)優(yōu)先級(jí)將數(shù)據(jù)轉(zhuǎn)發(fā)。軌道列車寬帶網(wǎng)絡(luò)實(shí)時(shí)性數(shù)據(jù)傳輸方法，包括以下步驟；數(shù)據(jù)終端設(shè)備配置要發(fā)送的數(shù)據(jù)流，并轉(zhuǎn)發(fā)至數(shù)據(jù)交換設(shè)備；所述數(shù)據(jù)流中包括實(shí)時(shí)數(shù)據(jù)幀，每個(gè)實(shí)時(shí)數(shù)據(jù)幀配置有數(shù)據(jù)計(jì)劃表，所述數(shù)據(jù)計(jì)劃表包括數(shù)據(jù)幀ID、數(shù)據(jù)幀計(jì)劃到達(dá)時(shí)間；更具體的說(shuō)，每個(gè)實(shí)時(shí)數(shù)據(jù)幀都有與其對(duì)應(yīng)的唯一的數(shù)據(jù)計(jì)劃表，數(shù)據(jù)計(jì)劃表中對(duì)應(yīng)的數(shù)據(jù)幀ID為唯一ID，作為實(shí)時(shí)數(shù)據(jù)幀的身份信息。數(shù)據(jù)交換設(shè)備接收數(shù)據(jù)，記錄實(shí)時(shí)數(shù)據(jù)幀到達(dá)時(shí)間，獲取實(shí)時(shí)數(shù)據(jù)幀長(zhǎng)度，為實(shí)時(shí)數(shù)據(jù)幀建立數(shù)據(jù)調(diào)度表，所述調(diào)度表中包含以下信息：數(shù)據(jù)幀到達(dá)時(shí)間、數(shù)據(jù)幀發(fā)送時(shí)間、數(shù)據(jù)幀ID、數(shù)據(jù)幀長(zhǎng)度及數(shù)據(jù)幀指定存放位置；所述指定存放位置是指數(shù)據(jù)幀在數(shù)據(jù)交換設(shè)備中的存放位置；所述數(shù)據(jù)幀發(fā)送時(shí)間，是以交換機(jī)的數(shù)據(jù)發(fā)送周期為基準(zhǔn)，與數(shù)據(jù)幀接收時(shí)間最近的數(shù)據(jù)發(fā)送周期對(duì)應(yīng)的時(shí)間；將數(shù)據(jù)調(diào)度表中內(nèi)容與數(shù)據(jù)計(jì)劃表中內(nèi)容比較，若數(shù)據(jù)調(diào)度表中的信息與數(shù)據(jù)計(jì)劃表中的信息一致，則將實(shí)時(shí)數(shù)據(jù)幀存放在數(shù)據(jù)幀指定存放位置，否則，丟棄該數(shù)據(jù)幀。本發(fā)明的有益效果為：(1)本發(fā)明基于同步以太網(wǎng)時(shí)鐘協(xié)議，提出了一種列車寬帶網(wǎng)絡(luò)實(shí)時(shí)性數(shù)據(jù)的傳輸系統(tǒng)和方法。傳輸系統(tǒng)將數(shù)據(jù)分為實(shí)時(shí)性數(shù)據(jù)、時(shí)間同步數(shù)據(jù)和傳統(tǒng)以太網(wǎng)數(shù)據(jù)(除時(shí)間同步數(shù)據(jù)和實(shí)時(shí)數(shù)據(jù)以外的非實(shí)時(shí)數(shù)據(jù))，針對(duì)不同的數(shù)據(jù)，采用不同的調(diào)度機(jī)制。(2)為實(shí)時(shí)數(shù)據(jù)配置時(shí)間戳，提供端到端專用通道，通過(guò)數(shù)據(jù)計(jì)劃表和數(shù)據(jù)調(diào)度表，數(shù)據(jù)傳輸具有嚴(yán)格確定的控制時(shí)序。(3)對(duì)時(shí)間同步數(shù)據(jù)和傳統(tǒng)以太網(wǎng)數(shù)據(jù)，采用轉(zhuǎn)發(fā)、查詢比較優(yōu)先級(jí)的方式轉(zhuǎn)發(fā)，確保此類數(shù)據(jù)按需傳輸。(4)與傳統(tǒng)的以太網(wǎng)數(shù)據(jù)傳輸方式相比，本發(fā)明帶寬利用率大幅度提升；數(shù)據(jù)傳輸具備極低的時(shí)延，微秒級(jí)抖動(dòng)；極大的降低了網(wǎng)絡(luò)環(huán)境對(duì)實(shí)時(shí)性數(shù)據(jù)傳輸?shù)挠绊憽８綀D說(shuō)明圖1為數(shù)據(jù)傳輸系統(tǒng)結(jié)構(gòu)框圖。圖2為數(shù)據(jù)傳輸系統(tǒng)硬件結(jié)構(gòu)圖。圖3為數(shù)據(jù)傳輸系統(tǒng)數(shù)據(jù)流向圖。圖4為實(shí)時(shí)數(shù)據(jù)處理流程圖。具體實(shí)施方式以下將結(jié)合附圖對(duì)本發(fā)明的具體實(shí)施方式進(jìn)行進(jìn)一步的描述。軌道列車寬帶網(wǎng)絡(luò)實(shí)時(shí)性數(shù)據(jù)傳輸系統(tǒng)，包括數(shù)據(jù)終端設(shè)備和數(shù)據(jù)交換設(shè)備；數(shù)據(jù)經(jīng)一數(shù)據(jù)終端設(shè)備發(fā)出，經(jīng)一個(gè)或多個(gè)數(shù)據(jù)交換設(shè)備中轉(zhuǎn)并最終到達(dá)另一以太網(wǎng)數(shù)據(jù)終端設(shè)備。本實(shí)施例中，數(shù)據(jù)終端設(shè)備采用以太網(wǎng)終端，數(shù)據(jù)交換設(shè)備采用以太網(wǎng)交換機(jī)。以太網(wǎng)終端分為源設(shè)備和宿設(shè)備，源設(shè)備為數(shù)據(jù)流發(fā)出設(shè)備，宿設(shè)備為數(shù)據(jù)流目的到達(dá)設(shè)備。同一數(shù)據(jù)傳遞路徑，源設(shè)備有一個(gè)，宿設(shè)備可為一個(gè)或多個(gè)，例如，若傳遞的數(shù)據(jù)流為多播或廣播，則會(huì)有多個(gè)宿設(shè)備。以太網(wǎng)終端或以太網(wǎng)交換機(jī)執(zhí)行以下功能模塊：同步時(shí)間戳模塊：記錄數(shù)據(jù)到達(dá)設(shè)備的時(shí)間；相應(yīng)的，若同步時(shí)間戳模塊配置在以太網(wǎng)終端，則記錄的為數(shù)據(jù)到以太網(wǎng)終端的時(shí)間，若同步時(shí)間戳模塊配置在以太網(wǎng)交換機(jī)，則記錄的為數(shù)據(jù)到達(dá)以太網(wǎng)交換機(jī)的時(shí)間。為降低對(duì)以太網(wǎng)終端的要求，本實(shí)施例中，將同步時(shí)間戳模塊配置在以太網(wǎng)交換機(jī)中實(shí)現(xiàn)。傳輸數(shù)據(jù)經(jīng)以太網(wǎng)終端到達(dá)以太網(wǎng)交換機(jī)時(shí)，先記錄數(shù)據(jù)到達(dá)以太網(wǎng)交換機(jī)的時(shí)間。除同步時(shí)間戳模塊外，以太網(wǎng)交換機(jī)內(nèi)還配置執(zhí)行以下模塊：數(shù)據(jù)校驗(yàn)?zāi)K：用于完成數(shù)據(jù)長(zhǎng)度和CRC校驗(yàn)；數(shù)據(jù)分類模塊：用于識(shí)別數(shù)據(jù)類型，將數(shù)據(jù)分為時(shí)間同步數(shù)據(jù)、傳統(tǒng)以太網(wǎng)數(shù)據(jù)和實(shí)時(shí)數(shù)據(jù)；數(shù)據(jù)處理模塊：包括實(shí)時(shí)數(shù)據(jù)處理模塊：用于接收數(shù)據(jù)分類模塊識(shí)別出的實(shí)時(shí)數(shù)據(jù)，并轉(zhuǎn)發(fā)。實(shí)時(shí)數(shù)據(jù)在列車上主要是過(guò)程數(shù)據(jù)，該類數(shù)據(jù)對(duì)傳輸有嚴(yán)格的時(shí)間要求；在以太網(wǎng)總線網(wǎng)絡(luò)中，采用周期性傳送，傳送頻率取決于實(shí)時(shí)數(shù)據(jù)的緊迫性。數(shù)據(jù)通過(guò)以上功能模塊處理，可實(shí)現(xiàn)在不影響傳統(tǒng)以太網(wǎng)數(shù)據(jù)傳輸?shù)那疤嵯拢_保實(shí)時(shí)數(shù)據(jù)在網(wǎng)絡(luò)中的實(shí)時(shí)傳輸，嚴(yán)格按照控制時(shí)序進(jìn)行數(shù)據(jù)流轉(zhuǎn)發(fā)。數(shù)據(jù)終端設(shè)備配置要發(fā)送的數(shù)據(jù)流；所述數(shù)據(jù)流中包括實(shí)時(shí)數(shù)據(jù)幀，每個(gè)實(shí)時(shí)數(shù)據(jù)幀配置有數(shù)據(jù)計(jì)劃表，所述數(shù)據(jù)計(jì)劃表包括數(shù)據(jù)幀ID、數(shù)據(jù)幀計(jì)劃到達(dá)時(shí)間；數(shù)據(jù)交換設(shè)備接收數(shù)據(jù)，記錄實(shí)時(shí)數(shù)據(jù)幀到達(dá)時(shí)間，獲取實(shí)時(shí)數(shù)據(jù)幀長(zhǎng)度，為實(shí)時(shí)數(shù)據(jù)幀建立數(shù)據(jù)調(diào)度表；調(diào)度表中包含以下信息：數(shù)據(jù)幀ID、數(shù)據(jù)幀到達(dá)時(shí)間、數(shù)據(jù)幀發(fā)送時(shí)間、數(shù)據(jù)幀長(zhǎng)度及數(shù)據(jù)幀指定存放位置；指定存放位置是指數(shù)據(jù)幀在數(shù)據(jù)交換設(shè)備中的存放位置；將數(shù)據(jù)調(diào)度表中內(nèi)容與數(shù)據(jù)計(jì)劃表中內(nèi)容比較，若數(shù)據(jù)調(diào)度表中的信息與數(shù)據(jù)計(jì)劃表中的信息一致，則將實(shí)時(shí)數(shù)據(jù)幀存放在數(shù)據(jù)幀指定存放位置，否則，丟棄該數(shù)據(jù)。以太網(wǎng)終端設(shè)備配置要發(fā)送的數(shù)據(jù)流；數(shù)據(jù)流中包括實(shí)時(shí)數(shù)據(jù)幀，每個(gè)實(shí)時(shí)數(shù)據(jù)幀配置有數(shù)據(jù)計(jì)劃表，數(shù)據(jù)計(jì)劃表包括數(shù)據(jù)幀ID、數(shù)據(jù)幀計(jì)劃到達(dá)時(shí)間。以太網(wǎng)終端設(shè)備配置好數(shù)據(jù)流之后，將數(shù)據(jù)流轉(zhuǎn)發(fā)出。數(shù)據(jù)交換設(shè)備接收數(shù)據(jù)，記錄實(shí)時(shí)數(shù)據(jù)幀到達(dá)時(shí)間，獲取實(shí)時(shí)數(shù)據(jù)幀長(zhǎng)度，為實(shí)時(shí)數(shù)據(jù)幀建立數(shù)據(jù)調(diào)度表；調(diào)度表中包含以下信息：數(shù)據(jù)幀ID、數(shù)據(jù)幀到達(dá)時(shí)間、數(shù)據(jù)幀發(fā)送時(shí)間、數(shù)據(jù)幀長(zhǎng)度及數(shù)據(jù)幀指定存放位置；指定存放位置是指數(shù)據(jù)幀在數(shù)據(jù)交換設(shè)備中的存放位置；將數(shù)據(jù)調(diào)度表中內(nèi)容與數(shù)據(jù)計(jì)劃表中內(nèi)容比較，若數(shù)據(jù)調(diào)度表中的信息與數(shù)據(jù)計(jì)劃表中的信息一致，則將實(shí)時(shí)數(shù)據(jù)幀存放在數(shù)據(jù)幀指定存放位置，否則，丟棄該數(shù)據(jù)幀。數(shù)據(jù)調(diào)度表中配置的數(shù)據(jù)幀發(fā)送時(shí)間，是以交換機(jī)的數(shù)據(jù)發(fā)送周期為基準(zhǔn)，與數(shù)據(jù)幀接收時(shí)間最近的數(shù)據(jù)發(fā)送周期對(duì)應(yīng)的時(shí)間。如圖2和圖3所示，為實(shí)時(shí)數(shù)據(jù)傳輸系統(tǒng)的一種實(shí)施方式結(jié)構(gòu)圖。本實(shí)施例中，主機(jī)1、主機(jī)2、主機(jī)3、主機(jī)4和主機(jī)5對(duì)應(yīng)的為以太網(wǎng)終端設(shè)備，交換機(jī)1、交換機(jī)2、交換機(jī)3、交換機(jī)4和交換機(jī)5對(duì)應(yīng)的為以太網(wǎng)交換機(jī)。其中：主機(jī)1經(jīng)交換機(jī)1、交換機(jī)2、交換機(jī)4與主機(jī)2和主機(jī)3之間建立數(shù)據(jù)傳遞鏈路；主機(jī)1經(jīng)交換機(jī)1、交換機(jī)2、交換機(jī)3和交換機(jī)5與主機(jī)4之間建立數(shù)據(jù)傳遞鏈路；主機(jī)1經(jīng)交換機(jī)1、交換機(jī)2、交換機(jī)3與主機(jī)5之間建立數(shù)據(jù)傳遞鏈路；主機(jī)2經(jīng)交換機(jī)4與主機(jī)3之間建立數(shù)據(jù)傳遞鏈路；主機(jī)3經(jīng)交換機(jī)4、交換機(jī)2與主機(jī)5之間建立數(shù)據(jù)傳遞鏈路；主機(jī)4經(jīng)交換機(jī)5、交換機(jī)3與主機(jī)5之間建立數(shù)據(jù)傳遞鏈路。其對(duì)應(yīng)數(shù)據(jù)流收發(fā)需求表如表1所示。表1數(shù)據(jù)流收發(fā)需求表數(shù)據(jù)流源設(shè)備宿設(shè)備數(shù)據(jù)幀長(zhǎng)度發(fā)送周期延遲抖動(dòng)數(shù)據(jù)流1主機(jī)1主機(jī)2，主機(jī)3456Byte32ms8ms8ms數(shù)據(jù)流2主機(jī)2主機(jī)356Byte64ms4ms8ms數(shù)據(jù)流3主機(jī)3主機(jī)532Byte128ms8ms8ms數(shù)據(jù)流4主機(jī)4主機(jī)5152Byte256ms4ms8ms如圖4所示，為數(shù)據(jù)流處理流程圖。以主機(jī)1到主機(jī)2和主機(jī)3的數(shù)據(jù)流傳遞鏈路為例。在主機(jī)1中配置待發(fā)送的數(shù)據(jù)流，數(shù)據(jù)流包括實(shí)時(shí)數(shù)據(jù)幀，每個(gè)實(shí)時(shí)數(shù)據(jù)幀配置有數(shù)據(jù)計(jì)劃表，數(shù)據(jù)計(jì)劃表包括數(shù)據(jù)幀ID、數(shù)據(jù)幀計(jì)劃到達(dá)各中轉(zhuǎn)交換機(jī)的時(shí)間。對(duì)應(yīng)該數(shù)據(jù)鏈路，包括數(shù)據(jù)幀到達(dá)交換機(jī)1的時(shí)間，數(shù)據(jù)幀到達(dá)交換機(jī)2的時(shí)間，數(shù)據(jù)幀到達(dá)交換機(jī)4的時(shí)間。數(shù)據(jù)流配置好后，首先轉(zhuǎn)發(fā)到交換機(jī)1，交換機(jī)1接收到數(shù)據(jù)流后，記錄實(shí)時(shí)數(shù)據(jù)幀到達(dá)交換機(jī)1的時(shí)間，獲取實(shí)時(shí)數(shù)據(jù)幀長(zhǎng)度，為實(shí)時(shí)數(shù)據(jù)幀建立數(shù)據(jù)調(diào)度表；調(diào)度表中包含以下信息：數(shù)據(jù)幀ID、數(shù)據(jù)幀到達(dá)時(shí)間、數(shù)據(jù)幀發(fā)送時(shí)間、數(shù)據(jù)幀長(zhǎng)度及數(shù)據(jù)幀在交換機(jī)1中的指定存放位置。此處所述數(shù)據(jù)幀到達(dá)時(shí)間是指其到達(dá)交換機(jī)1的時(shí)間，由同步時(shí)間戳模塊獲??；數(shù)據(jù)幀長(zhǎng)度由數(shù)據(jù)校驗(yàn)?zāi)K獲取。交換機(jī)1將數(shù)據(jù)調(diào)度表中內(nèi)容與數(shù)據(jù)計(jì)劃表中內(nèi)容比較，若數(shù)據(jù)調(diào)度表中的信息與數(shù)據(jù)計(jì)劃表中的信息一致，數(shù)據(jù)幀ID相匹配、數(shù)據(jù)幀計(jì)劃到達(dá)交換機(jī)1的時(shí)間與數(shù)據(jù)幀到達(dá)交換機(jī)1的時(shí)間相匹配，則認(rèn)為該數(shù)據(jù)為可靠準(zhǔn)確的數(shù)據(jù)，將實(shí)時(shí)數(shù)據(jù)幀存放在數(shù)據(jù)幀在交換機(jī)1中的指定存放位置，否則，丟棄該數(shù)據(jù)幀。交換機(jī)1中數(shù)據(jù)計(jì)劃調(diào)度表中數(shù)據(jù)幀發(fā)送時(shí)間是指數(shù)據(jù)計(jì)劃從交換機(jī)1發(fā)送到交換機(jī)2的時(shí)間，為保證數(shù)據(jù)傳輸?shù)膶?shí)時(shí)性，以數(shù)據(jù)幀到達(dá)交換機(jī)1的時(shí)間和交換機(jī)1的發(fā)送頻率為基準(zhǔn)，選取與數(shù)據(jù)幀到達(dá)交換機(jī)1最接近的交換機(jī)發(fā)送時(shí)間作為數(shù)據(jù)幀發(fā)送時(shí)間。若數(shù)據(jù)為可靠準(zhǔn)確的數(shù)據(jù)，在制定位置緩存后，將在與其存儲(chǔ)時(shí)間最近的一個(gè)交換機(jī)1發(fā)送周期轉(zhuǎn)發(fā)。交換機(jī)2接收到交換機(jī)1轉(zhuǎn)發(fā)的數(shù)據(jù)，為數(shù)據(jù)幀建立數(shù)據(jù)調(diào)度表，記錄實(shí)時(shí)數(shù)據(jù)幀到達(dá)交換機(jī)2的時(shí)間，獲取實(shí)時(shí)數(shù)據(jù)幀長(zhǎng)度，為實(shí)時(shí)數(shù)據(jù)幀建立數(shù)據(jù)調(diào)度表；同樣包含以下信息：數(shù)據(jù)幀ID、數(shù)據(jù)幀到達(dá)時(shí)間、數(shù)據(jù)幀發(fā)送時(shí)間、數(shù)據(jù)幀長(zhǎng)度及數(shù)據(jù)幀在交換機(jī)2中的指定存放位置。此處所述數(shù)據(jù)幀到達(dá)時(shí)間是指其到達(dá)交換機(jī)2的時(shí)間，由同步時(shí)間戳模塊獲??；數(shù)據(jù)幀長(zhǎng)度由數(shù)據(jù)校驗(yàn)?zāi)K獲取。交換機(jī)2將數(shù)據(jù)調(diào)度表中內(nèi)容與數(shù)據(jù)計(jì)劃表中內(nèi)容比較，若數(shù)據(jù)調(diào)度表中的信息與數(shù)據(jù)計(jì)劃表中的信息一致，數(shù)據(jù)幀ID相匹配、數(shù)據(jù)幀計(jì)劃到達(dá)交換機(jī)2的時(shí)間與數(shù)據(jù)幀到達(dá)交換機(jī)2的時(shí)間相匹配，則認(rèn)為該數(shù)據(jù)為可靠準(zhǔn)確的數(shù)據(jù)，將實(shí)時(shí)數(shù)據(jù)幀存放在數(shù)據(jù)幀在交換機(jī)2中的指定存放位置，否則，丟棄該數(shù)據(jù)幀。交換機(jī)2中數(shù)據(jù)計(jì)劃調(diào)度表中數(shù)據(jù)幀發(fā)送時(shí)間是指數(shù)據(jù)計(jì)劃從交換機(jī)2發(fā)送到交換機(jī)4的時(shí)間，為保證數(shù)據(jù)傳輸?shù)膶?shí)時(shí)性，以數(shù)據(jù)幀到達(dá)交換機(jī)2的時(shí)間和交換機(jī)2的發(fā)送頻率為基準(zhǔn)，選取與數(shù)據(jù)幀到達(dá)交換機(jī)1最接近的交換機(jī)發(fā)送時(shí)間作為數(shù)據(jù)幀發(fā)送時(shí)間。若數(shù)據(jù)為可靠準(zhǔn)確的數(shù)據(jù)，在制定位置緩存后，將在與其存儲(chǔ)時(shí)間最近的一個(gè)交換機(jī)2發(fā)送周期轉(zhuǎn)發(fā)。交換機(jī)4獲取交換機(jī)2轉(zhuǎn)發(fā)的數(shù)據(jù)，并執(zhí)行與交換機(jī)1及交換機(jī)2同樣的數(shù)據(jù)處理流程，為數(shù)據(jù)幀配置數(shù)據(jù)調(diào)度表。交換機(jī)4中數(shù)據(jù)調(diào)度表對(duì)應(yīng)的數(shù)據(jù)到達(dá)時(shí)間是指數(shù)據(jù)幀到達(dá)交換機(jī)4的時(shí)間，數(shù)據(jù)發(fā)送時(shí)間是指數(shù)據(jù)幀經(jīng)由交換機(jī)4發(fā)出的時(shí)間。交換機(jī)4將有效數(shù)據(jù)轉(zhuǎn)發(fā)，最終由主機(jī)2和主機(jī)3獲取，完成實(shí)時(shí)數(shù)據(jù)傳遞過(guò)程。更具體的說(shuō)，列車上的數(shù)據(jù)除實(shí)時(shí)數(shù)據(jù)外，還包括時(shí)間同步數(shù)據(jù)和傳統(tǒng)以太網(wǎng)數(shù)據(jù)。除實(shí)時(shí)數(shù)據(jù)外，本系統(tǒng)對(duì)對(duì)時(shí)間同步數(shù)據(jù)和傳統(tǒng)以太網(wǎng)數(shù)據(jù)采用以下處理流程。更進(jìn)一步的，為實(shí)現(xiàn)對(duì)時(shí)間同步數(shù)據(jù)和傳統(tǒng)以太網(wǎng)數(shù)據(jù)的轉(zhuǎn)發(fā)，可以區(qū)分時(shí)間同步數(shù)據(jù)和傳統(tǒng)以太網(wǎng)數(shù)據(jù)(此處，傳統(tǒng)以太網(wǎng)數(shù)據(jù)是指除時(shí)間同步數(shù)據(jù)和實(shí)時(shí)數(shù)據(jù)之外的以太網(wǎng)數(shù)據(jù))，數(shù)據(jù)處理模塊還進(jìn)一步包括同步數(shù)據(jù)處理模塊：用于接收數(shù)據(jù)分類模塊轉(zhuǎn)發(fā)的時(shí)間同步數(shù)據(jù)并轉(zhuǎn)發(fā)；傳統(tǒng)以太網(wǎng)數(shù)據(jù)處理模塊：用于接收數(shù)據(jù)分類模塊轉(zhuǎn)發(fā)的轉(zhuǎn)發(fā)傳統(tǒng)以太網(wǎng)數(shù)據(jù)并轉(zhuǎn)發(fā)。軌道列車寬帶網(wǎng)絡(luò)實(shí)時(shí)性數(shù)據(jù)傳輸系統(tǒng)還包括配置于數(shù)據(jù)交換設(shè)備中的：優(yōu)先級(jí)裁決模塊：用于接收同步數(shù)據(jù)處理模塊和以太網(wǎng)數(shù)據(jù)處理模塊轉(zhuǎn)發(fā)的數(shù)據(jù)，裁斷接收到時(shí)間同步數(shù)據(jù)或以太網(wǎng)數(shù)據(jù)的優(yōu)先級(jí)，并根據(jù)數(shù)據(jù)優(yōu)先級(jí)將數(shù)據(jù)轉(zhuǎn)發(fā)；多路選擇模塊：用于接收優(yōu)先級(jí)裁決模塊及實(shí)時(shí)數(shù)據(jù)處理模塊轉(zhuǎn)發(fā)的數(shù)據(jù)，裁斷接收到數(shù)據(jù)的優(yōu)先級(jí)，并根據(jù)數(shù)據(jù)優(yōu)先級(jí)將數(shù)據(jù)轉(zhuǎn)發(fā)。具體的說(shuō)，優(yōu)先級(jí)裁決模塊轉(zhuǎn)發(fā)的時(shí)間同步數(shù)據(jù)、傳統(tǒng)以太網(wǎng)數(shù)據(jù)和實(shí)時(shí)數(shù)據(jù)處理模塊轉(zhuǎn)發(fā)的實(shí)時(shí)數(shù)據(jù)都會(huì)到達(dá)多路選擇模塊，由多路選擇模塊根據(jù)數(shù)據(jù)優(yōu)先級(jí)將其接收到的數(shù)據(jù)轉(zhuǎn)發(fā)。其中，實(shí)時(shí)數(shù)據(jù)的優(yōu)先級(jí)最高，時(shí)間同步數(shù)據(jù)和傳統(tǒng)以太網(wǎng)數(shù)據(jù)的優(yōu)先級(jí)取決于具體設(shè)定。(1)傳統(tǒng)以太網(wǎng)數(shù)據(jù)在列車控制網(wǎng)絡(luò)中，消息數(shù)據(jù)、流數(shù)據(jù)等類型數(shù)據(jù)，相對(duì)于過(guò)程數(shù)據(jù)，實(shí)時(shí)性要求不高，通常采用非周期的按需發(fā)送。因此，可采用傳統(tǒng)以太網(wǎng)數(shù)據(jù)傳輸。數(shù)據(jù)分類模塊將傳統(tǒng)以太網(wǎng)數(shù)據(jù)幀轉(zhuǎn)發(fā)的傳統(tǒng)以太網(wǎng)數(shù)據(jù)處理模塊。數(shù)據(jù)交換設(shè)備為傳統(tǒng)以太網(wǎng)數(shù)據(jù)幀配置MAC地址轉(zhuǎn)發(fā)表，當(dāng)數(shù)據(jù)幀到達(dá)傳統(tǒng)以太網(wǎng)數(shù)據(jù)處理模塊，將數(shù)據(jù)幀目的MAC地址和源MAC地址用來(lái)進(jìn)行數(shù)據(jù)MAC地址轉(zhuǎn)發(fā)表的查詢和學(xué)習(xí)。數(shù)據(jù)交換設(shè)備可能會(huì)出現(xiàn)多個(gè)端口同時(shí)到達(dá)數(shù)據(jù)幀的情況。因此，需要有機(jī)制確保各數(shù)據(jù)幀查詢轉(zhuǎn)發(fā)表的先后順序。然后，根據(jù)MAC地址查表，如果命中，便得到該幀應(yīng)該從哪一個(gè)端口發(fā)送出去的信息，否則就廣播該幀，對(duì)源MAC地址進(jìn)行學(xué)習(xí)，學(xué)習(xí)的過(guò)程分為三個(gè)步驟：1)查詢MAC地址轉(zhuǎn)發(fā)表，如果源MAC地址在表中，則執(zhí)行(2)；否則執(zhí)行步驟(3)；2)更新MAC地址轉(zhuǎn)發(fā)表；3)將源MAC地址存入MAC地址轉(zhuǎn)發(fā)表中；當(dāng)出現(xiàn)多個(gè)端口同時(shí)到達(dá)數(shù)據(jù)幀的情況時(shí)，按照幀優(yōu)先級(jí)先后進(jìn)行裁決，誰(shuí)先進(jìn)入下步查表操作。這樣，減少了幀的時(shí)延、抖動(dòng)。(2)時(shí)間同步數(shù)據(jù)時(shí)間同步數(shù)據(jù)，主要實(shí)現(xiàn)整個(gè)列車控制網(wǎng)絡(luò)中，所有數(shù)據(jù)交換設(shè)備保持時(shí)間同步。優(yōu)先級(jí)可設(shè)置比上述兩類數(shù)據(jù)低。時(shí)間同步數(shù)據(jù)采用廣播轉(zhuǎn)發(fā)。當(dāng)前第1頁(yè)1 2 3