# 网络通信 & 网络架构 Network Communication and Organization
# Grade 2 ( 5-7岁 ) 要掌握的程度
Computer networks can be used to connect people to other people, places, information, and ideas. The Internet enables people to connect with others worldwide through many different points of connection.
Small, wireless devices, such as cell phones, communicate with one another through a series of intermediary connection points, such as cellular towers. This coordination among many computing devices allows a person to voice call a friend or video chat with a family member. Details about the connection points are not expected at this level.
Crosscutting Concepts: Communication and Coordination; Human–Computer Interaction Connections Within Framework: K–2.Impacts of Computing.Social Interactions; K–2.Data and Analysis.Collection; 3–5.Impacts of Computing.Social Interactions
计算机网络可以把人们和其他人、其他地方、其他信息和其他想法连接起来. 互联网使人们能够通过各种连接点与世界各地的人联系起来.
小型的无线设备, 比如手机, 通过一系列的连接点(比如电话信号塔)进行通信. 这种设备之间的协调合作使得给朋友打语音电话或者与家人视频聊天成为可能.
对于这个阶段的学生, 关于网络连接点的细节是不需要了解的.
# Grade 5 ( 8-11岁 ) 要掌握的程度
Information needs a physical or wireless path to travel to be sent and received, and some paths are better than others. Information is broken into smaller pieces, called packets, that are sent independently and reassembled at the destination. Routers and switches are used to properly send packets across paths to their destinations.
There are physical paths for communicating information, such as ethernet cables, and wireless paths, such as Wi-Fi. Often, information travels on a combination of physical and wireless paths; for example, wireless paths originate from a physical connection point. The choice of device and type of connection will affect the path information travels and the potential bandwidth (the capacity to transmit data or bits in a given timeframe). Packets and packet switching (the method used to send packets) are the foundation for further understanding of Internet concepts. At this level, the priority is understanding the flow of information, rather than details of how routers and switches work and how to compare paths.
Crosscutting Concept: Communication and Coordination Connections Within Framework: 3–5.Computing Systems.Devices; 3–5. Computing Systems.Troubleshooting
信息需要通过物理连接或者无线连接来发送和接收. 首先, 信息被分解成”数据包“(很小的碎片信息), 然后数据包分别传送, 最终在目的地重新组合恢复 (“路由器”和“交换机”正是用来正确高效地将数据包传输到目的地的设备)
数据传输有物理路径(比如以太网电缆), 还有无线路径(比如 wifi). 通常，数据不会在纯粹的物理路径或者纯粹的无线路径上传输, 而是在这两者上共同传输. 比如说, 无线路径本身就源于物理连接点(wifi传输本身就依靠实体连接的网络设备).
其中, 设备和连接类型的选择, 将影响数据传输的路径和带宽速度（即一定时间内能够传输多少比特[1]的数据).
”数据包“和”数据包交换“(即用于发送数据包的方法)是进一步理解互联网的基础.
不过, 这个阶段的学生, 只需要理解信息传输的过程, 不需要了解路由器和交换机是如何工作的.
# Grade 8 ( 11-14岁 ) 要掌握的程度
Computers send and receive information based on a set of rules called protocols. Protocols define how messages between computers are structured and sent. Considerations of security, speed, and reliability are used to determine the best path to send and receive data.
Protocols allow devices with different hardware and software to communicate, in the way that people with different native languages may use a common language for business. Protocols describe established commands and responses between computers on a network, such as requesting data or sending an image. There are many examples of protocols including TCP/IP (Transmission Control Protocol/Internet Protocol) and HTTP (Hypertext Transfer Protocol), which serve as the foundation for formatting and transmitting messages and data, including pages on the World Wide Web. Routers also implement protocols to record the fastest and most reliable paths by sending small packets as tests. The priority at this grade level is understanding the purposeof protocols, while knowing details of how specific protocols work is not expected.
Crosscutting Concepts: Communication and Coordination; Abstraction; Privacy and Security Connection Within Framework: 6–8.Data and Analysis.Storage
计算机根据一套称为”协议“的规则来发送和接收数据. ”协议“定义了计算机之间数据的结构和传送方式, ”协议“主要保证数据传输中的安全、速度、可靠性.
“协议”允许不同软硬件设备之间相互通信, 就像不同国家的人使用英语这个共同“协议”来沟通一样. “协议”描述了网络上计算机之间既定的命令和响应信息(比如, 规定了请求数据和发送图像的命令).
很多协议成为数据传输的基础, 协议包括 TCP/IP (传输控制协议/互联网协议) 和 HTTP (超文本传输协议), 因特网上的网页数据, 依赖于这些协议.
我们生活中常见的路由器就会执行这些协议, 它通过发送小数据包进行测试, 筛选出速度最快和最可靠的路径, 然后再进行传输.
这个阶段的学生主要是理解协议的目的和意义, 并不需要了解具体的协议细节.
# Grade 12 ( 14-18岁 ) 要掌握的程度
Network topology is determined, in part, by how many devices can be supported. Each device is assigned an address that uniquely identifies it on the network. The scalability and reliability of the Internet are enabled by the hierarchy and redundancy in networks.
Large-scale coordination occurs among many different machines across multiple paths every time a web page is opened or an image is viewed online. Devices on the Internet are assigned an Internet Protocol (IP) address to allow them to communicate. The design decisions that directed the coordination among systems composing the Internet also allowed for scalability and reliability. Scalability is the capability of a network to handle a growing amount of work or its potential to be enlarged to accommodate that growth.
Crosscutting Concepts: Communication and Coordination; Abstraction; System Relationships Connections Within Framework: 9–12.Computing Systems.Devices; 9–12. Computing Systems.Hardware and Software; 9–12.Impacts of Computing.Social Interactions
网络拓扑结构, 部分意义上是由它支持的设备数量决定的. 网络上的每个设备都会被分配一个地址, 作为这个设备在网络上唯一的身份识别.
因特网的可扩展性和可靠性, 是由网络的层次和冗余促成的.
每次打开网页或者在线浏览图片时, 大量不同设备之间就会进行大规模的协调. 因特网为连接的设备都分配了唯一的IP地址(互联网协议地址), 作为这个设备唯一的身份识别, 以方便它们之间进行通信而不会引起混乱. 设计互联网协议的时候, 不光需要考虑上述的数据协调能力, 还要考虑整个系统的可扩展性和可靠性(“可扩展性”是指一个网络处理不断增长的工作量的能力, 或其通过改造能够适应工作量增长的潜在可能)
"比特"是英语“bit”的音译, “bit”是“binary digit“的意思, 即”二进制数字“. 1个比特就表示1位二进制数字 ↩︎