OSI模型

The OSI model is a reference model which most IT professionals use to describe networks and network applications.OSI模型是一个参考模式,运用最专业的网络与网络应用来形容.51Testing软件测试网 |ef(q[DU5xfI

The OSI model was originally intended to describe a complete set of production network protocols, but the cost and complexity of the government processes involved in defining the OSI network made the project unviable.OSI模型原本描述了一整套生产网络议定书但成本和复杂的过程,政府确定了互连网络工程不可行. In the time that the OSI designers spent arguing over who would be responsible for what, TCP/IP conquered the world.在当时互连设计师花争论谁负责什么、传输/庆征服世界.51Testing软件测试网A(|?G!la(Ru[

The seven layers of the OSI model are:7层OSI模型有:51Testing软件测试网O*A U iS1u5W3u

The easiest way to remember the layers of the OSI model is to use the handy mnemonic "All People Seem To Need Data Processing":最容易记住的层层OSI模型是要用好用记忆"一切仿佛需要数据处理":51Testing软件测试网1M/i&?%}#pfDX qq6TU'i

The functions of the seven layers of the OSI model are:职能OSI模型的七个层分别是:

Layer Seven of the OSI Model7层的OSI模型

The Application Layer of the OSI model is responsible for providing end-user services, such as file transfers, electronic messaging, e-mail, virtual terminal access, and network management.应用层OSI模型负责提供最终用户服务,如档案转移、电子信息、电子邮件、虚拟终端接入、网络管理. This is the layer with which the user interacts.这是层与用户互动.51Testing软件测试网Cd_P)GS B

Layer Six of the OSI Model6层的OSI模型

The Presentation Layer of the OSI model is responsible for defining the syntax which two network hosts use to communicate.表示OSI模型层负责确定哪两个网络主机使用语法沟通. Encryption and compression should be Presentation Layer functions.应套层加密和压缩功能.51Testing软件测试网6I4D'ZR-o,q y

Layer Five of the OSI Model5层的OSI模型

The Session Layer of the OSI model is responsible for establishing process-to-process commnunications between networked hosts.会议层是OSI模型的建立过程中,负责对联网主机之间commnunications进程.

Layer Four of the OSI Model4层的OSI模型

The Transport Layer of the OSI model is responsible for delivering messages between networked hosts.OSI模型的运输层负责将信息网络之间的主机. The Transport Layer should be responsible for fragmentation and reassembly.运输层应负责不成改头换面.

Layer Three of the OSI Model3层的OSI模型

The Network Layer of the OSI model is responsible for establishing paths for data transfer through the network.OSI模型的网络层负责通过建立网络数据传输通道. Routers operate at the Network Layer.路由器运行在网络层.

Layer Two of the OSI ModelOSI模型的两个层51Testing软件测试网/`X']#tb
pf

The Data Link Layer of the OSI model is responsible for communications between adjacent network nodes.数据链路层的OSI模型是负责沟通、相邻网络节点. Hubs and switches operate at the Data Link Layer.开关运转枢纽和数据链路层.51Testing软件测试网/\]
oa,NOg

Layer One of the OSI ModelOSI模型层之一

The Physical Layer of the OSI model is responsible for bit-level transmission between network nodes.OSI模型的物理层负责有点层次之间传输网络节点. The Physical Layer defines items such as: connector types, cable types, voltages, and pin-outs.物理层定义的项目,如:连接器型号电缆类型、电压、边奏.51Testing软件测试网&OB(jA%qU

The OSI Model vs. The Real WorldOSI模型与现实世界

The most major difficulty with the OSI model is that is does not map well to the real world!最重要的是,OSI模型的困难是没有好到现实世界地图!51Testing软件测试网 S/EU/y6}B.GtB

The OSI was created after many of todays protocols were already in production use.该系统互连后形成的许多人已经在生产使用today's议定书. These existing protocols, such as TCP/IP, were designed and built around the needs of real users with real problems to solve.这些现有议定书等的TCP/庆设计并围绕用户的实际需要,