201218686 六、發明說明： 【發明所屬之技術領域】 本發明涉及通信領域，更具體地，涉及一種快速地通 知移動節點的離開以釋放移動節點的組播資源的方法和裝 置。 【先前技術】 近年來，無線局域網（WLAN )技術被廣泛用於私人 家庭和公共熱點區域。對於中國的主要營運商，包括中國 電信、中國移動和中國聯通，構建大規模的WiFi/WLAN 網路成爲它們的主要策略（例如，中國電信的 C + W( CDMA + WiFi)策略）。對於所有營運商，有效地使用所部 署的WiFi網路並獲得收益是部署大規模WiFi網路的最終 目的。 基於組播（multicast)的移動IPTV是WiFi網路營運商 可以給WiFi用戶提供的一種服務，尤其是對於WiFi熱點 /熱點區域中的用戶。WiFi用戶還可以使用智慧型電話、 PDA和裝備有WiFi卡的筆記型電腦來使用移動IPTV服務 。因此，希望設計一種能夠擴展已有的基於有線網路的 IPTV服務的解決方案。 然而，在將傳統的IPTV服務擴展到移動網路過程中 存在一些技術問題。其中一個技術問題是由於WiFi用戶 的移動性和原有組播不支持移動性的特性之間的矛盾所引 起的。 -5- 201218686 在移動期間’當IPTV移動節點（MN)從之前的WiFi 存取網路（舊的存取點AP/存取控制器AC)移動到新的 WiFi存取網路（新的AP/AC)時，應該在WiFi存取網路 中支持切換機制。 但是’由於以下原因’現有的切換機制的性能較差： 1. 當MN切換後離開時，具有傳統IEEE 802.11網路 介面的MN無法立即自動地向之前的WiFi存取網路發送 基於網際網路群組管理通訊協定IGMP ( Internet Group Management Protocol)的組播離開訊息以觸發組播離開過 程。 2. 另一方面’爲了實現更好的QoS/QoE並增加故障容 錯能力，使用IEEE ?02.1 le以及其他WiFi多媒體（WMM )機制的下行鏈路WiFi存取點通常具有緩衝儲存機制以 使用其介面將WMM業務傳送給其相關的MN。 因此，最差情況是網路側無法知道MN離開（尤其是 具有快速移動性的MN )，並且無法及時地停止組播複製 ，因而所複製的業務仍然被傳送給之前的AP以緩衝儲存 。因此，如果在該通道僅存在一個用戶，則浪費了組播複 製和下行鏈路資源。即使AP在一段時間之後知道MN離 開了，由於沒有相關機制，也無法通知上行鏈路組播控制 器以停.止組播複製。 當IPTV組播網路給大跫移動用戶提供服務，並且移 動用戶高速移動時’上述情況尤其嚴重。從Wi-Fi網路的 角度看，這種資源佔用的累積效應將導致IPTV服務崩潰 201218686 ，甚至威脅到整個Wi-Fi網路業務投放的穩定型。 移動IPTV是一種新興技術。尙不存在考慮MN的移 動性的、在WiFi網路中快速地觸發IPTV組播服務的終止 和相關資源釋放的機制。IPTV組播機制在設計之初並未 考慮到用戶的移動性。 針對該技術問題，在設計移動IPTV的技術方案時’ 提出了 一種方法，其中在之前的 WiFi存取網路和新的 WiFi存取網路之間進行訊息傳遞，交換MN所需的資訊以 進行更好的切換（例如MN的安全模組）。因此，之前的 WiFi存取網路可以根據來自新的WiFi存取網路的訊息， 觸發組播複製的停止，並釋放與組播相關的資源。但是， 該方法有時無法有效地運行： 1. MN從之前的WiFi存取網路離開到完全進入新的 WiFi存取網路並與之建立關聯之間存在一定的時間間隔 ，因此，該方法仍然無法即時地、有效地停止組播複製。 2. 新WiFi存取網路與之前的WiFi存取網路之間的通 信並不是一定存在，這種新舊存取網路之間的通信往往只 是作爲一種驗證最佳化機制。 3. 此外，更重要的是，移動的MN在離開當前的AP/AC 之後並不一定再存取新的WiFi網路。在這種情況下，沒 有新的存取網路來發送相關通知，所以MN之前的WiFi 存取網路無法及時地獲知MN的離開。 因此，需要一種能夠及時回應MN的移動 '並能夠快 速通知存取網路停止組播複製並釋放相關資源的方法。 201218686 【發明內容】 鑒於現有技術的上述缺點，本發明提出了一種在移動 節點離開存取網路時及時地通知網路側的方法和裝置，其 中’監控存取網路中該移動節點的存取埠狀態，在網路存 取埠的狀態發生變化而指示移動節點離開了存取網路時， 通知網路側’從而回應於移動節點離開存取網路而快速地 停止組播複製並釋放相關資源。 根據本發明的第一態樣，提出了 一種向組播代理通知 移動節點的離開的方法，包括步驟監控該移動節點的網 路存取埠的狀態；以及當網路存取埠的狀態發生改變以標 識移動節點離開時，向組播代理通知移動節點的離開。 較佳地，在該移動節點存取該網路存取埠以接收組播 服務時，啓動對該移動節點的監控。 較佳地，由該組播代理觸發對該移動節點的監控。 較佳地，在該網路存取埠應用IEEE 802.1X協議，並 且透過監控AuthControlledPortStatus參數.來監控網路存 取埠的狀態。 較佳地，如果 AuthControlledPortStatus由授權狀態 變爲未授權狀態’則標識該移動節點離開了該網路存取埠 〇 較佳地，透過向組播代理發送網際網路群組管理通訊 協定IG Μ P離開訊息，向組播代理通知移動節點的離開。 較佳地，該方法還包括步驟：組播代理釋放與離開的 -8- 201218686 移動節點相關的組播資源。 根據本發明的第二態樣，提出了 一種向組播代理通知 移動節點的離開的裝置’包括：監控器，監控該移動節點 的網路存取埠的狀態；以及通知單元，當網路存取埠的狀 態發生改變以指示移動節點離開時，向組播代理通知移動 節點的離開。 較佳地’在該移動節點存取該網路存取埠以接收組播 服務時，啓動該監控器對該移動節點進行監控。 較佳地，由該組播代理觸發該監控器對該移動節點進 行監控。 較佳地，該監控器透過監控IEEE 802.IX協定中 AuthControlledPortStatus參數來監控網路存取埠的狀態。 較佳地，其中，如果 AuthControlledPortStatus由授 權狀態變爲未授權狀態，則指示該移動節點離開了該網路 存取埠。 較佳地，該通知單元透過向組播代理發送網際網路群 組管理通訊協定IGMP離開訊息，向組播代理通知移動節 點的離開。 較佳地，該監控器中儲存有狀態列表；以儲存該移動 節點的網路存取埠的狀態。 相較於最相近的現有技術，即在之前的WiFi存取網 路和新的WiFi存取網路之間進行訊息傳遞以獲知移動節 點的離開的技術方案，本發明可以更加快速地獲知移動節 點的離開，而且不會由於移動節點並未存取新的存取網路 -9 - 201218686 而無法獲知移動節點的離開。 【實施方式】 下面’根據附圖描述本發明。在以下描述中，一些具 體實施例僅用於描述目的，而不應該理解爲對本發明有任 何限制’而只是本發明的示例。在可能導致對本發明的理 解造成混淆時，將省略常規結構或構造。 根據本發明的原理，由於移動節點存取WLAN的埠的 狀態即時地反映了移動節點與WLAN的連接狀況，因此監 控移動節點與WLAN之間的埠的狀態，並回應於埠狀態變 爲斷開，即指示移動節點離開該WLAN，立即向提供組播 業務的組播代理通知移動節點的離開，就可以回應於移動 節點的移動而快速地通知網路側以停止組播複製並釋放相 關資源。 作爲基於埠的存取控制技術，IEEE 802. IX [參見/五五五 Std 8 0 2. IX-2001, IEEE Standard for Port-Based Network hcew Coniro/]被廣泛採用，作爲 WLAN的認證入口。 IEEE 8 02. IX的認證方即時地維護埠狀態的狀態機。根據 IEEE 8 02. IX，如果MN離開或從所指定的埠登出，則埠 的狀態快速地從授權狀態變爲未授權狀態。因此，分配給 MN的埠即時地反映了 MN的移動性。 下面以移動節點存取基於IEEE 802. IX的WLAN的情 況爲例進行說明。當然，本領域技術人員可以明瞭’除了 IEEE 8 02.IX，本發明的原理同樣適用於基於其他協議的 -10- 201218686 WLAN。 圖1示出了根據本發明實施例的向組播代理通知移動 節點的離開的系統的示意方塊圖。 如圖1所示，組播代理1 00是駐留在有線/無線存取 網路中的現有網路模組，用於執行組播管理和控制功能（ 例如，組播業務複製）。 認證伺服器3 00給認證方提供認證服務的實體。認證 伺服器3 00可以與認證方位於相同位置，但是通常是認證 方的一個外部伺服器。 認證方400是要求對鏈路的另一端的實體進行認證的 實體。 請求方500是由認證方400認證並且希望存取認證方 的服務的實體。 埠存取實體PAE是埠相關聯的協定實體，可以支援認 證方、申請方或者它們兩方的功能。 在根據本發明的實施例的系統中，請求方是移動節點 MN，其向認證方請求存取WLAN。組播代理1 00向存取 WLAN的移動節點提供組播業務。 在根據本發明實施例的系統中，佈置有埠狀態監視器 PSM 2 00，連接在組播代理1〇〇和認證方PAE 401之間， 用於監控.MN的IEEE 8 02.1 X埠，並在檢測到埠狀態變化 時通知組播代理1 0 0。 圖2示出了圖1所示系統中的向組播代理通知移動節 點的離開的裝置的示意框圖。在圖1所示系統中，向組播 -11 - 201218686 代理通知移動節點的離開的裝置即埠狀態監視器200。 如圖2所示，埠狀態監視器200包括：監控器201， 用於監控網路存取埠的狀態；以及通知單元202，用於在 監視器20 1發現移動節點離開的事件時，向組播代理通知 該事件。 首先，PSM 200中的監控器201被觸發以針對MN進 行監控。在被觸發以進行監控之後，PSM將該MN添加到 其監控列表中，並監控該MN的IEEE 8 02.1 X埠的狀態》 PSM儲存有綁定列表，該綁定列表透過單元組<MN 的MAC位址，埠ID，埠狀態 >，記錄了被監.控的MN的 MAC位址及其埠狀態。 該單元組中的相關實體的定義如下： 1)埠：埠是網路存取埠的簡稱，其被定義爲系統（這裏 是MN)存取到局域網的連接點（p〇A，Point of Attachment )。它可以是實體埠，例如連接到實體WLAN段的單個 LAN MAC ;或者是邏輯埠，例如MN與存取點（AP )之 間的IEEE 802.1 1 WLAN關聯。被分配給成功認證的MN 的埠在802.IX中被稱爲“受控埠”。 2 )埠ID :埠ID是埠所在的系統給各個埠所分配的 库號。 3 )埠狀態：存在一個認證器PAE狀態機，以反映每 個埠的埠狀態。狀態機可被配置爲具有一定時間間隔的即 時狀態更新（例如每秒更新一次）。 在成功認證之後，具有授權狀態的受控埠被分配給 -12- 201218686 MN。監控該MN的PSM中的綁定列表中的單元組<MN的 MAC位址，埠ID，埠狀態 >成爲<MN的MAC位址，埠ID ，授權>。 在認證方的狀態機檢測到MN離開時，在802. IX認證 方中所閉合埠的狀態將變爲未授權狀態。受控埠的兩個狀態 “授權”和“未授權”在 IEEE 802.1X 中由 AuthControlledPortStatus 參數表示。 PSM 根據認證方 PAE 的 AuthControlledPortStatus 的 値來監控受控MN的淳狀態。如果AuthControlledPortStatus 指示從授權狀態變爲未授權狀態，則P S Μ中的通知單元 將被觸發以向組播代理發送IGMP離開訊息（或其他通知 訊息），以觸發針對該ΜΝ的組播離開機制，並觸發IPTV 組播上行鏈路或下行鏈路的資源釋放。監控該ΜΝ的PSM 中的綁定列表中的單元組<ΜΝ的MAC位址，埠ID，埠狀 態 >成爲<MN的MAC位址，埠ID，未授權 >。此後，由於 MN的離開，PSM可以將該MN從其監控列表中刪除。 [PSM及其監控觸發機制] 如圖1所示，PSM 200負責與IEEE 802.IX中定義的 認證器PAE以及組播代理1 〇〇進行互動。透過以下兩種方 法，可以觸發PSM以監控組播MN的IEEE 802.1 X埠狀態 〇 1)主動觸發模式：PSM被設計爲具有IGMP監聽機 制（IGMP Snooping)的能力。PSM執行即時的IGMP監 -13- 201218686 聽機制，以獲取新加入組播組的MN的組播資訊。一旦獲 得新加入組播的MN組播存取確認，則PSM將被進一步觸 發監測該MN的IEEE 802.IX埠狀態； 2)被動觸發模式：由組播代理透過訊息來通知PSM 。該訊息包括MN的組播資訊<MN MAC位址，組播IP位 址 >。然後，PSM被觸發以監控該MN的IEEE 8 02. IX埠 狀態。 如果選擇被動觸發模式，則需要在組播代理和PSM 之間進行MN組播資訊的傳送。由於需要組播代理和PCM 之間的更多的通信，因此相比較而言，主動觸發模式更加 有效並且集中。 根據IEEE 8 02.IX，如果MN離開或從所指定的埠登 出，則埠的狀態快速地從授權狀態變爲未授權狀態。一旦 PSM檢測到所分配的埠被關閉，則建立IGMP離開訊息， 並向組播代理1 00發送IGMP離開訊息以通知組播代理 1 〇〇 (或上行鏈路中的組播複製控制器）。組播代理1 00 將執行相關的組播離開機制和釋放資源的動作（例如， DSL AM存取網路環境中的本地轉發表更新）〇 根據本發明實施例的方法由於監控MN的存取埠的狀 態，可以及時地終止組播複製，因此更加有效。 圖3示出了根據本發明實施例的向組播代理通知移動 節點的離開的方法的流程圖。 如圖3所示，首先，在步驟S101，MN存取WLAN。4 認證方PAE的狀態機指示該MN的存取埠的埠狀態爲授權 -14- 201218686 狀態。按照上述主動觸發模式或被動觸發模式，觸發PSM 以監控存取了 WLAN的MN，即將該MN添加到PSM的監 控列表中。作爲示例，這裏假定MN具有MAC位址1、埠 1。PSM的綁定列表中針對該MN的單元組是<MAC位址1 ，埠1，授權> ^ 在步驟S 1 02處，被監控的MN離開（斷開或註銷） 〇 作爲回應，在步驟S103，認證方PAE的狀態機發生狀 態轉換，指示MN的存取埠的埠狀態由授權狀態變爲未授權 狀態。認證方 PAE 向 PSM 發送包含 AuthControlledPortStatus 的訊息。 在步驟S104，PSM更新其綁定列表。單元組<MAC位 址1，埠1，授權 >變爲<MAC位址1，埠1，未授權> ^ 然後在步驟S105，PSM透過向組播代理發送IGMP離 開訊息，通知組播代理。組播代理將觸發組播離開機制， 並釋放與該MN相關的組播資源。此時，PSM還可將該 MN從其監控列表中刪除。 在根據本發明實施例的向組播代理通知移動節點的離 開的方法中，基於IEEE 802. IX的認證方所維護的狀態機 提供了埠狀態。如果MN離開或從所指定的埠登出，則埠 狀態快速地從授權狀態變爲未授權狀態。由此，透過監控 埠狀態的變化，可以及時地向組播代理通知移動節點的離 開。使用PSM對埠狀態的監控和與組播代理的交互機制 ，組播代理可以立即知道MN離開了，並且及時釋放爲組 -15- 201218686 播所預留的資源。此外，也可以有效地觸發其他相關 的釋放（例如針對IEEE 802.1 1 e或其他WMM機制的 儲存清空）。這有效地增強了移動IPTV組播在大 WiFi/WLAN網路中的應用的可行性和穩健性。 從上面的描述可以看出，本發明並不局限於基於 8 02.1 X的WLAN。本發明的原理同樣適用於能夠監控 態並向網路側報告埠狀態變化的其他WLAN。此外， 實際的部署’根據本發明的方法簡單且有效。 這裏所公開的本發明實施例的其他設置包括執行 前槪述並隨後詳述的方法實施例的步驟和操作的軟體 。更具體地，電腦程式產品是如下的一種實施例：具 腦可讀媒體，電腦可讀媒體上編碼有電腦程式邏輯， 計算設備上執行時，電腦程式邏輯提供相關的操作， 提供上述單向代理轉密方案。當在計算系統的至少一 理器上執行時，電腦程式邏輯使得處理器執行本發明 例所述的操作（方法）。本發明的這種設置典型地提 設置或編碼在例如光媒體（例如CD-ROM)、軟碟或 等的電腦可讀媒體上的軟體、程式碼和/或其他資料 、或者諸如一個或多個ROM或RAM或PROM晶片上 體或微程式碼的其他媒體、或專用積體電路（ASIC ) —個或多個模組中的可下載的軟體圖像、共用資料庫 軟體或韌體或這種配置可安裝在計算設備上，以使得 設備中的一個或多個處理器執行本發明實施例所述的 。結合諸如一組資料通信設備或其他實體中的計算設 資源 緩衝 規模 IEEE 埠狀 對於 在先 程式 有電 當在 從而 個處 實施 供爲 硬碟 結構 的韌 、或 等。 計算 技術 備進 -16- 201218686 行操作的軟體過程也可以提供根據本發明的系統。根據本 發明的系統也可以分佈在多個資料通信設備上的多個軟體 過程、或者在一組小型專用電腦上運行的所有軟體過程、 或者單個電腦上運行的所有軟體過程之間。 應該理解，嚴格地講，本發明的實施例可以實現爲電 腦設備上的軟體程式、軟體和硬體、或者單獨的軟體和/ 或單獨的電路。 以上描述僅給出了本發明的較佳實施例，而並不是要 以任何方式限制本發明。因此，本發明的範圍應涵蓋在本 發明精神和原理內進行的任何修改、替換、改進。 【圖式簡單說明】 結合附圖，根據下面對本發明的非限制性實施例的詳 細描述，本發明的上述及其他目的、特徵和優點將變得更 加清楚，附圖中： 圖1示出了根據本發明實施例的向組播代理通知移動 節點的離開的系統的示意方塊圖； 圖2示出了圖1所示系統中的向組播代理通知移動節 點的離開的裝置的示意方塊圖；以及 圖3示出了根據本發明實施例的向組播代理通知移動 節點的離開的方法的流程圖。 附圖中，用相同的附圖標記表示相關的單元，以示出 它們之間的相關性。以加粗的實線表示主要反映了本發明 的發明思想的那些單元。 -17- 201218686 【主要元件符號說明】 100 :組播代理 200 :埠狀態監視器 3 00 :認證伺服器 4 0 0 :認證方 4 0 1 :認證方P A E 402 : WLAN 存取201218686 VI. Description of the Invention: [Technical Field] The present invention relates to the field of communications, and more particularly to a method and apparatus for quickly notifying a departure of a mobile node to release a multicast resource of a mobile node. [Prior Art] In recent years, wireless local area network (WLAN) technology has been widely used in private homes and public hotspot areas. For China's major operators, including China Telecom, China Mobile and China Unicom, building large-scale WiFi/WLAN networks has become their main strategy (for example, China Telecom's C + W (CDMA + WiFi) strategy). For all operators, the effective use of the deployed WiFi network and the gains are the ultimate goal of deploying a large-scale WiFi network. Multicast-based mobile IPTV is a service that WiFi network operators can provide to WiFi users, especially for users in WiFi hotspots/hotspots. WiFi users can also use mobile IPTV services using smart phones, PDAs and laptops equipped with WiFi cards. Therefore, it is desirable to design a solution that can extend existing wired network-based IPTV services. However, there are some technical problems in extending the traditional IPTV service to the mobile network. One of the technical problems is caused by the contradiction between the mobility of WiFi users and the characteristics of the original multicast that does not support mobility. -5- 201218686 During the mobile period, when the IPTV mobile node (MN) moves from the previous WiFi access network (old access point AP/access controller AC) to the new WiFi access network (new AP) /AC), the switching mechanism should be supported in the WiFi access network. However, the performance of the existing handover mechanism is poor due to the following reasons: 1. When the MN leaves after handover, the MN with the traditional IEEE 802.11 network interface cannot immediately and automatically send the Internet-based network to the previous WiFi access network. The multicast management message of the group management protocol IGMP (Internet Group Management Protocol) triggers the multicast leaving process. 2. On the other hand 'In order to achieve better QoS/QoE and increase fault tolerance, downlink WiFi access points using IEEE ?02.1 le and other WiFi Multimedia (WMM) mechanisms typically have a buffer storage mechanism to use their interfaces. The WMM service is delivered to its associated MN. Therefore, the worst case is that the network side cannot know that the MN is leaving (especially the MN with fast mobility) and cannot stop multicast replication in time, so the copied service is still transmitted to the previous AP to buffer the storage. Therefore, if there is only one user in the channel, then multicast replication and downlink resources are wasted. Even if the AP knows that the MN has left after a certain period of time, the uplink multicast controller cannot be notified to stop multicast replication because there is no relevant mechanism. This is especially true when the IPTV multicast network provides services to large mobile users and mobile users move at high speeds. From the perspective of Wi-Fi networks, the cumulative effect of such resource consumption will cause IPTV services to collapse 201218686, and even threaten the stability of the entire Wi-Fi network service. Mobile IPTV is an emerging technology. There is no mechanism for quickly triggering termination of IPTV multicast services and related resource release in a WiFi network, considering the mobility of the MN. The IPTV multicast mechanism was not designed with user mobility in mind. In response to this technical problem, when designing a mobile IPTV technology solution, a method is proposed in which a message is transmitted between a previous WiFi access network and a new WiFi access network, and information required by the MN is exchanged for performing. Better switching (such as MN's security module). Therefore, the previous WiFi access network can trigger the stop of multicast replication and release the resources related to multicast according to the message from the new WiFi access network. However, this method sometimes does not work effectively: 1. There is a certain time interval between the departure of the MN from the previous WiFi access network and the complete entry into and association with the new WiFi access network. It is still not possible to stop multicast replication immediately and effectively. 2. Communication between the new WiFi access network and the previous WiFi access network does not necessarily exist. Communication between the old and new access networks is often only used as a verification optimization mechanism. 3. In addition, more importantly, the mobile MN does not necessarily access the new WiFi network after leaving the current AP/AC. In this case, there is no new access network to send the relevant notification, so the WiFi access network before the MN cannot know the MN's departure in time. Therefore, there is a need for a method that can respond to the MN's mobile in time and can quickly notify the access network to stop multicast replication and release related resources. 201218686 SUMMARY OF THE INVENTION In view of the above disadvantages of the prior art, the present invention proposes a method and apparatus for notifying a network side in time when a mobile node leaves an access network, wherein 'monitoring access of the mobile node in the access network The state of the network, when the state of the network access changes and indicates that the mobile node leaves the access network, notifies the network side to quickly stop multicast replication and release related resources in response to the mobile node leaving the access network. . According to a first aspect of the present invention, a method for notifying a multicast agent of a departure of a mobile node includes the steps of monitoring a state of network access of the mobile node; and changing a state of network access When the mobile node is identified to leave, the multicast agent is notified of the departure of the mobile node. Preferably, when the mobile node accesses the network access to receive the multicast service, monitoring of the mobile node is initiated. Preferably, the monitoring of the mobile node is triggered by the multicast proxy. Preferably, the IEEE 802.1X protocol is applied to the network access, and the status of the network access port is monitored by monitoring the AuthControlledPortStatus parameter. Preferably, if the AuthControlledPortStatus changes from the authorized state to the unauthorized state, the mobile node is identified as leaving the network access, preferably by sending an internet group management protocol IG Μ P to the multicast proxy. Leave the message and notify the multicast agent of the departure of the mobile node. Preferably, the method further comprises the step of: the multicast agent releasing the multicast resource associated with the leaving -8-201218686 mobile node. According to a second aspect of the present invention, a device for notifying a multicast agent of a departure of a mobile node includes: a monitor that monitors a state of network access of the mobile node; and a notification unit that stores the network When the state of the mash changes to indicate that the mobile node is away, the multicast agent is notified of the departure of the mobile node. Preferably, the monitor is activated to monitor the mobile node when the mobile node accesses the network access to receive the multicast service. Preferably, the monitor is triggered by the multicast agent to monitor the mobile node. Preferably, the monitor monitors the status of network access by monitoring the AuthControlledPortStatus parameter in the IEEE 802.IX protocol. Preferably, if the AuthControlledPortStatus changes from an authorized state to an unauthorized state, the mobile node is instructed to leave the network access port. Preferably, the notification unit notifies the multicast agent of the departure of the mobile node by transmitting an Internet Group Management Protocol IGMP Leave message to the multicast proxy. Preferably, the monitor stores a status list; to store the state of the network access port of the mobile node. Compared with the most recent prior art, that is, the technical solution of transmitting the message between the previous WiFi access network and the new WiFi access network to learn the departure of the mobile node, the present invention can learn the mobile node more quickly. The departure, and will not be able to know the departure of the mobile node because the mobile node does not access the new access network -9 - 201218686. [Embodiment] Hereinafter, the present invention will be described based on the drawings. In the following description, some specific embodiments are for illustrative purposes only and are not to be construed as limiting. Conventional structures or configurations will be omitted when it may cause confusion to the understanding of the present invention. According to the principle of the present invention, since the state of the 节点 of the mobile node accessing the WLAN instantly reflects the connection status of the mobile node with the WLAN, the state of the 埠 between the mobile node and the WLAN is monitored, and the status changes to the disconnection in response to the 埠 state. That is, the mobile node is instructed to leave the WLAN, and immediately informs the mobile agent that provides the multicast service of the departure of the mobile node, and can quickly notify the network side to stop the multicast replication and release the related resources in response to the mobile node's movement. As a 埠-based access control technology, IEEE 802. IX [see / 559 Std 8 0 2. IX-2001, IEEE Standard for Port-Based Network hcew Coniro/] is widely adopted as a WLAN authentication entry. The authenticator of IEEE 8 02. IX maintains the state machine of the state in real time. According to IEEE 8 02. IX, if the MN leaves or logs out from the specified port, the state of 埠 quickly changes from the authorized state to the unauthorized state. Therefore, the 分配 assigned to the MN instantly reflects the mobility of the MN. The following is an example of a case where a mobile node accesses an IEEE 802.IX-based WLAN. Of course, those skilled in the art will appreciate that the principles of the present invention are equally applicable to the -10- 201218686 WLAN based on other protocols, except for IEEE 8 02.IX. 1 shows a schematic block diagram of a system for notifying a multicast agent of the departure of a mobile node in accordance with an embodiment of the present invention. As shown in Figure 1, the multicast proxy 100 is an existing network module residing in a wired/wireless access network for performing multicast management and control functions (e.g., multicast service replication). The authentication server 300 provides an entity that authenticates the authentication service. Authentication Server 300 can be in the same location as the authenticator, but is typically an external server of the authenticator. The authenticator 400 is an entity that requires authentication of an entity at the other end of the link. The requesting party 500 is an entity that is authenticated by the authenticating party 400 and wishes to access the authenticator's services. The access entity PAE is an associated contract entity that can support the functions of the authenticator, the applicant, or both. In a system according to an embodiment of the invention, the requesting party is a mobile node MN requesting access to the WLAN from the authenticating party. The multicast proxy 100 provides multicast services to mobile nodes accessing the WLAN. In a system according to an embodiment of the present invention, a UI status monitor PSM 2 00 is arranged, connected between the multicast proxy 1A and the authenticator PAE 401, for monitoring the IEEE 8 02.1 X埠 of the .MN, and Notify the multicast proxy 1 0 0 when a change in the state is detected. Figure 2 is a schematic block diagram of an apparatus for notifying a multicast agent of the departure of a mobile node in the system of Figure 1. In the system shown in Fig. 1, the device that notifies the multicast node -11 - 201218686 of the leaving of the mobile node is the status monitor 200. As shown in FIG. 2, the status monitor 200 includes: a monitor 201 for monitoring the status of the network access port; and a notification unit 202 for reporting to the group when the monitor 20 1 finds that the mobile node is away. The broadcast agent notifies the event. First, the monitor 201 in the PSM 200 is triggered to monitor for the MN. After being triggered for monitoring, the PSM adds the MN to its monitoring list and monitors the status of the IEEE 8.02.1X of the MN. The PSM stores a binding list that is transmitted through the unit group <MN The MAC address, 埠ID, 埠 state>, records the MAC address of the monitored MN and its 埠 state. The related entities in the unit group are defined as follows: 1) 埠: 埠 is the abbreviation of network access ,, which is defined as the connection point of the system (here MN) to the local area network (p〇A, Point of Attachment) ). It can be a physical port, such as a single LAN MAC connected to a physical WLAN segment; or a logical port, such as an IEEE 802.1 1 WLAN association between a MN and an access point (AP). The 被 assigned to a successful authenticated MN is referred to as "controlled 埠" in 802.IX. 2) 埠ID: 埠ID is the library number assigned to each 系统 by the system where 埠 is located. 3) 埠 state: There is an authenticator PAE state machine to reflect the 埠 state of each 。. The state machine can be configured to have instant status updates with a certain time interval (e.g., updated once per second). After successful authentication, a controlled port with an authorized status is assigned to -12-201218686 MN. The cell group <MN's MAC address, 埠ID, & state > in the binding list in the PSM of the MN is monitored as <MN's MAC address, 埠ID, Authorization>. When the authenticator's state machine detects that the MN is leaving, the state of the closed state in the 802. IX authenticator will become unauthorised. Two states of "controlled" and "unauthorized" are represented by the AuthControlledPortStatus parameter in IEEE 802.1X. The PSM monitors the state of the controlled MN based on the AuthControlledPortStatus of the authenticator PAE. If the AuthControlledPortStatus indication changes from the authorized state to the unauthorized state, the notification unit in the PS 将 will be triggered to send an IGMP Leave message (or other notification message) to the multicast proxy to trigger the multicast leave mechanism for that ,, and Triggering the release of resources on the IPTV multicast uplink or downlink. The unit address <ΜΝ's MAC address, 埠ID, & state > in the binding list in the PSM of the 监控 is monitored as <MN's MAC address, 埠ID, unauthorized >. Thereafter, due to the departure of the MN, the PSM can delete the MN from its monitoring list. [PSM and its monitoring trigger mechanism] As shown in Figure 1, the PSM 200 is responsible for interacting with the authenticator PAE and multicast proxy 1 defined in IEEE 802.IX. The PSM can be triggered to monitor the IEEE 802.1 X埠 state of the multicast MN through the following two methods: 1) Active trigger mode: The PSM is designed to have the capability of IGMP Snooping (IGMP Snooping). The PSM performs an immediate IGMP supervision -13-201218686 listening mechanism to obtain multicast information of the MN newly joined to the multicast group. Once the newly added multicast MN multicast access acknowledgment is obtained, the PSM will be further triggered to monitor the IEEE 802.IX state of the MN; 2) Passive trigger mode: The multicast agent notifies the PSM through the message. The message includes the MN's multicast information <MN MAC address, multicast IP address >. The PSM is then triggered to monitor the IEEE 8 02. IX state of the MN. If the passive trigger mode is selected, the MN multicast information needs to be transmitted between the multicast proxy and the PSM. The active trigger mode is more efficient and centralized compared to the need for more communication between the multicast agent and the PCM. According to IEEE 8 02.IX, if the MN leaves or logs out from the specified port, the state of 埠 quickly changes from the authorized state to the unauthorized state. Once the PSM detects that the assigned port is closed, an IGMP Leave message is established and an IGMP Leave message is sent to the Multicast Agent 100 to inform the Multicast Agent 1 (or the Multicast Replication Controller in the Uplink). The multicast proxy 100 will perform the associated multicast leave mechanism and release of resources (eg, local forwarding table updates in the DSL AM access network environment). The method according to an embodiment of the invention monitors the access of the MN. The status can be terminated in a timely manner, so it is more efficient. 3 shows a flow chart of a method of notifying a multicast agent of the departure of a mobile node in accordance with an embodiment of the present invention. As shown in FIG. 3, first, in step S101, the MN accesses the WLAN. 4 The state machine of the authenticator PAE indicates that the access status of the MN is the authorized -14-201218686 status. According to the above active trigger mode or passive trigger mode, the PSM is triggered to monitor the MN that accesses the WLAN, that is, the MN is added to the monitoring list of the PSM. As an example, it is assumed here that the MN has a MAC address of 1, 埠 1. The unit group for the MN in the binding list of the PSM is <MAC address 1, 埠1, Authorization> ^ At step S102, the monitored MN leaves (disconnects or deregisters) 〇 as a response, in Step S103, the state machine of the authenticator PAE changes state, indicating that the 埠 state of the MN's access 由 changes from the authorized state to the unauthorized state. The authenticator PAE sends a message to the PSM containing AuthControlledPortStatus. At step S104, the PSM updates its binding list. The unit group <MAC address 1, 埠 1, authorization > becomes <MAC address 1, 埠 1, unauthorized > ^ Then in step S105, the PSM transmits the IGMP Leave message to the multicast agent, notifying the group Broadcast agent. The multicast proxy will trigger the multicast leave mechanism and release the multicast resources associated with the MN. At this point, the PSM can also remove the MN from its monitoring list. In the method of notifying the multicast agent of the leaving of the mobile node according to an embodiment of the present invention, the state machine maintained by the IEEE 802.IX-based authenticator provides the 埠 state. If the MN leaves or logs out from the specified port, the 埠 state quickly changes from the authorized state to the unauthorized state. Thus, by monitoring the change in state, the multicast agent can be notified of the departure of the mobile node in time. Using PSM to monitor the state of the 和 and interact with the multicast agent, the multicast agent can immediately know that the MN has left, and release the resources reserved for the group -15-201218686 broadcast in time. In addition, other related releases can also be effectively triggered (e.g., storage empties for IEEE 802.1 1 e or other WMM mechanisms). This effectively enhances the feasibility and robustness of mobile IPTV multicast applications in large WiFi/WLAN networks. As can be seen from the above description, the present invention is not limited to a WLAN based on 802.1X. The principles of the present invention are equally applicable to other WLANs that are capable of monitoring states and reporting 埠 state changes to the network side. Moreover, the actual deployment 'method according to the invention is simple and effective. Other arrangements of the embodiments of the invention disclosed herein include software that performs the steps and operations of the method embodiments described above and subsequently detailed. More specifically, the computer program product is an embodiment in which a brain readable medium is encoded on a computer readable medium with computer program logic, and when executed on a computing device, the computer program logic provides related operations to provide the one-way agent described above. Transfer plan. When executed on at least one of the computing systems, the computer program logic causes the processor to perform the operations (methods) described in the examples of the present invention. Such an arrangement of the present invention typically provides software, code, and/or other material, such as one or more, that is disposed or encoded on a computer readable medium such as an optical media (eg, CD-ROM), floppy disk, or the like. ROM or RAM or other medium on the PROM chip or microcode, or an integrated integrated circuit (ASIC) - downloadable software image in one or more modules, shared library software or firmware or this The configuration can be installed on the computing device such that one or more processors in the device perform the embodiments of the present invention. Combining computing resources such as a set of data communication devices or other entities to buffer the size of the IEEE 埠 对于 对于 对于 在 在 在 对于 对于 对于 对于 对于 对于 对于 对于 对于 对于 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在 在Computational Techniques -16- 201218686 The software process of line operations can also provide a system in accordance with the present invention. The system in accordance with the present invention can also be distributed between multiple software processes on multiple data communication devices, or all software processes running on a small set of dedicated computers, or between all software processes running on a single computer. It should be understood that, strictly speaking, embodiments of the invention may be implemented as software programs, software and hardware on a computer device, or as separate software and/or separate circuits. The above description is only illustrative of preferred embodiments of the invention and is not intended to limit the invention in any way. Therefore, the scope of the invention should be construed to cover any modifications, alterations, and improvements in the spirit and scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will become more apparent from A schematic block diagram of a system for notifying a multicast agent of a leaving of a mobile node in accordance with an embodiment of the present invention; FIG. 2 is a schematic block diagram of an apparatus for notifying a multicast agent of a leaving of a mobile node in the system of FIG. 1; And FIG. 3 shows a flow chart of a method of notifying a multicast agent of the departure of a mobile node in accordance with an embodiment of the present invention. In the drawings, the relevant elements are denoted by the same reference numerals to illustrate the correlation between them. Those elements which mainly reflect the inventive concept of the present invention are indicated by bold solid lines. -17- 201218686 [Description of main component symbols] 100 : Multicast proxy 200 : 埠 status monitor 3 00 : Authentication server 4 0 0 : Authenticator 4 0 1 : Authenticator P A E 402 : WLAN access
5 00 :請求方 501 ： MN PAE 201 :監控器 202 :通知單元5 00 : Requester 501 : MN PAE 201 : Monitor 202 : Notification Unit