ipx網際網路分組交換協議

X.25 is a packet-switched network technology used long before ago. X.25 is one of the first packet-switched network used to transmit data between multiple hosts. In this tutorial, we will define the X.25 protocol as well as the X.25 standard, history, network equipment, and components.

X.25是很久以前使用的一種分組交換網路技術。 X.25是用於在多個主機之間傳輸資料的第一個分組交換網路之一。 在本教程中，我們將定義X.25協議以及X.25標準，歷史記錄，網路裝置和元件。

X.25分組交換 (X.25 Packet Switching)

As its name suggests X.25 is a packet-switching technology that is used to transmit data between different host locations. X.25 uses HDLC packets which also contains some information about the routing like source and destination address.

顧名思義，X.25是一種分組交換技術，用於在不同主機位置之間傳輸資料。 X.25使用HDLC資料包，其中還包含有關路由的一些資訊，例如源地址和目標地址。

X.25標準 (X.25 Standard)

X.25 protocol is created by the International Telecommunication Union (ITU) in 1976. Originally X.25 is created to carry voice signals over the telephone lines. But later the capability of the X.25 is used for network and internet communication. X.25 encompasses the first 3 layers of the OSI Reference model which are Physical Layer, Data Link Layer, Network Layer. X.25 was a very popular late 1970s and 1980s among the telecommunication and IT world. The latest version of the X.25 standard is released in 1996.

X.25協議是由國際電信聯盟(ITU)於1976年建立的。最初X.25的建立是為了在電話線上承載語音訊號。 但是後來X.25的功能用於網路和Internet通訊。 X.25包含OSI參考模型的前3層，分別是物理層，資料鏈路層，網路層。 X.25在1970年代和1980年代後期在電信和IT世界中非常流行。 X.25標準的最新版本於1996年釋出。

X.25的特徵 (Characteristics of X.25)

X.25 network protocol provides some characteristics.

X.25網路協議提供了一些特性。

• The packet size varies from 64 bytes to 4096 bytes where 128 bytes is the default packet size. If the packet size is different for multiple DTE and DCE the packets will be fragmented.
  資料包大小從64位元組到4096位元組不等，其中128位元組是預設資料包大小。 如果多個DTE和DCE的資料包大小不同，則資料包將被分段。
• X.25 is a low-speed network for today’s internet speeds. X.25 provides speed around 100kbps and below.
  X.25是當今網際網路速度的低速網路。 X.25提供大約100kbps及以下的速度。
• X.25 is used to create faster and newer network communication protocols like ATM and Frame Relay.
  X.25用於建立更快和更新的網路通訊協議，例如ATM和幀中繼。
• X.25 is a very robust protocol because it is debugged and inspected heavily from its creation from the 1970s. Literally there is no data error on modern X.25 networks.
  X.25是一種非常強大的協議，因為它從1970年代建立以來就經過大量除錯和檢查。 從字面上看，現代X.25網路上沒有資料錯誤。
• Another problematic attribute of the X.25 protocol is its delay because of the DCE’s store and forward mechanism.
  X.25協議的另一個有問題的屬性是由於DCE的儲存和轉發機制而導致的延遲。

X.25網路裝置和元件 (X.25 Network Equipment and Components)

Some equipment and terms are used to fully implement the X.25 network. Here are some of the most important of them.

一些裝置和術語用於完全實現X.25網路。 以下是其中一些最重要的內容。

• `Data Terminal Equipment (DTE)` is used on the end-user, device or host part in order to terminate the X.25 network.
  在終端使用者，裝置或主機部分使用“資料終端裝置(DTE)”以終止X.25網路。
• `Data Circuit-Terminating Equipment (DCE)` is used to route the X.25 packets between DTE devices. Multiple DCE devices are used to connect the DTE’s and other DCE devices together.
  “資料電路終結裝置(DCE)”用於在DTE裝置之間路由X.25資料包。 多個DCE裝置用於將DTE和其他DCE裝置連線在一起。
• `Switched Virtual Circuits (SVC’s)` are like virtual connections between different DTE’s. They can be created by using different DCE’s to connect the same two DTE’s. Every time a transmission session will occur a new SVC is created.
  交換虛擬電路(SVC)就像不同DTE之間的虛擬連線。 可以通過使用不同的DCE連線相同的兩個DTE來建立它們。 每次發生傳輸會話時，都會建立一個新的SVC。
• `Permanent Virtual Circuits (PVC’s)` are similar to the leased line where the connection is always established between two DTE’s. There is no need to set-up phase.
  “永久虛擬電路(PVC)”類似於租用線路，其中始終在兩個DTE之間建立連線。 無需設定階段。

X.25物理層 (X.25 Physical Layer)

The physical layer of the X.25 provides some communication lines which transmit electrical signals according to V.35, RS232, and X.21 standards. The physical layer is simply copper lines that are used for telephone communication.

X.25的物理層提供了一些通訊線路，這些線路根據V.35，RS232和X.21標準傳輸電訊號。 物理層只是用於電話通訊的銅線。

X.25資料鏈路層 (X.25 Data Link Layer)

Data Link layer is one of the most important parts of the X.25 protocol. Data Link Layer provides error-free communication and transmission between two X.25 nodes. X.25 provides the error checking mechanism in each hop during transmission. This can create some delay. X.25 packets are generally shorter than other protocol packets which are generally 128 or 256 bytes.

資料鏈路層是X.25協議最重要的部分之一。 資料鏈路層提供了兩個X.25節點之間的無錯通訊和傳輸。 X.25在傳輸過程中的每個跳中提供了錯誤檢查機制。 這會造成一些延遲。 X.25資料包通常比其他協議資料包短，通常為128或256位元組。

X.25網路層 (X.25 Network Layer)

X.25 network layer simply used to manage end-to-end communication between different DTE devices. The network layer also governs set-up and teardown and flow control between the DTE devices as well as routing function with multiplexing multiple logical or virtual connections ver single physical connection.

X.25網路層僅用於管理不同DTE裝置之間的端到端通訊。 網路層還通過在單個物理連線上覆用多個邏輯或虛擬連線，來管理DTE裝置之間的建立和拆除以及流控制以及路由功能。

翻譯自: https://www.poftut.com/what-is-x-25-packet-switching-network-protocol/

ipx網際網路分組交換協議