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IPv4 Data Flows IPv4數據流

In Internet protocol version 4, there are three types of data flows that can occur: unicast, broadcast, and multicast.

在Internet協議版本4中，可以發生三種類型的數據流：單播，廣播和多播。

The most common and most widely used is called unicast. In unicast communication, data travels from a single device to another single device on the network. For example, when you go to www.google.com in your web browser, your computer makes a request to one of Google’s web servers using unicast communication, and one of Google’s computers then sends the data back using unicast communication to just your computer.

最常見和最廣泛使用的方法稱為單播。在單播通信中，數據從網絡上的單個設備傳輸到另一個單個設備。例如，當您使用網絡瀏覽器訪問www.google.com時，您的計算機使用單播通信向一台Google的網絡服務器發出請求，然後其中一台Google的計算機通過單播通信將數據發送回您的計算機。

When data is sent as a broadcast communication, it travels from a single device (such as your computer) to every other device on the network. This data will not travel outside the current subnet, though, when using broadcast. An example of broadcast communications would be if your system administrator was going to shut down a switch for maintenance. She may send out a broadcast message to everyone connected to that switch, warning them that their connectivity is going to be lost in the next ten minutes. You can think of this type of messaging like a teacher who is about to announce the next homework assignment. The teacher may say (or broadcast), “Class, here is your homework for tonight.” The message is directed at everyone in the class (or subnet) and they all should receive the message.

當數據作為廣播通信發送時，它從單個設備（例如您的計算機）傳輸到網絡上的所有其他設備。但是，使用廣播時，該數據不會在當前子網之外傳播。例如，如果您的系統管理員要關閉交換機進行維護，則為廣播通信。她可能會向連接到該交換機的每個人發出廣播消息，警告他們在接下來的十分鐘內將失去連接。您可以將這種消息傳遞想像為即將宣布下一個作業的老師。老師可能會說（或廣播）“課，這是你今晚的作業”。該消息針對班級（或子網）中的每個人，他們所有人都應該收到該消息。

The final method of data travel is called multicast. In multicast communication, data travels from a single device to multiple other devices on the network, but not necessarily to all of them, like it does when using broadcast communication. Also, this can expand outside of a single subnet. This works well when sharing a resource, such as streaming video. You can think of this type of communication as the Internet equivalent of watching satellite TV. For satellite TV, the signal is being sent out, but you have to “tune in” in order to receive (view) the data.

數據傳輸的最終方法稱為多播。在多播通信中，數據從單個設備傳輸到網絡上的多個其他設備，但不一定要傳輸到所有其他設備，就像使用廣播通信時那樣。而且，這可以擴展到單個子網之外。在共享資源（例如流視頻）時，此方法效果很好。您可以將這種類型的通信視為觀看衛星電視的互聯網。對於衛星電視，正在發送信號，但是您必須“調入”才能接收（查看）數據。

IPv4 Address Classes IPv4地址類別 << Previous Next >> Assigning an IP Address 分配IP地址