相关联的的网络知识
A computer network or data network is a telecommunications network which allows computers to exchange data. In computer networks, networked computing devices exchange data with each other using a data link. The connections between nodes are established using either cable media or wireless media. The best-known computer network is the Internet. Network computer devices that originate, route and terminate the data are called network nodes.[1]
计算机网络或者数据网络是电信网络它允许计算机之间交换数据
发起，路由和终止数据的网络计算机设备称为网络节点
Nodes can include hosts such as personal computers, phones, servers as well as networking hardware. Two such devices can be said to be networked together when one device is able to exchange information with the other device, whether or not they have a direct connection to each other. Computer networks differ in the transmission medium used to carry their signals, communications protocols to organize network traffic, the network's size, topology and organizational intent.
Computer networks support an enormous number of applications and services such as access to the World Wide Web, digital video, digital audio, shared use of application and storage servers, printers, and fax machines, and use of email and instant messaging applications as well as many others. In most cases, application-specific communications protocols are layered (i.e. carried as payload) over other more general communications protocols.
节点可以包括主机，例如个人计算机，电话，服务器以及网络硬件,当一个设备能够与另一设备交换信息时，两个这样的设备可以被称为联网在一起，无论它们是否具有彼此的直接连接。计算机网络在用于承载其信号的传输介质方面不同,通信协议来组织网络流量，网络的大小，拓扑和组织意图。
data link是什么？
In telecommunication a data link is the means of connecting one location to another for the purpose of transmitting and receiving digital information
将一个位置连接到另一个位置以用于发送和接收数字信息
看到这就有问题了什么是node?
Node (networking)Node (networking))
In communication networks, a node (Latin nodus, ‘knot’) is either a connection point, a redistribution point (e.g. data communications equipment), or a communication endpoint (e.g. data terminal equipment). The definition of a node depends on the network and protocol layer referred to. A physical network node is an active electronic device that is attached to a network, and is capable of creating, receiving, or transmitting information over a communications channel.[1] A passive distribution point such as a distribution frame or patch panel is consequently not a node.
在通信网络中，节点是连接点，重新分发点（例如数据通信设备）或通信端点（例如数据终端设备）。 节点的定义取决于所涉及的网络和协议层。 物理网络节点是附接到网络的有源电子设备，并且能够通过通信信道创建，接收或发送信息。[1] 因此，诸如配线架或接线板的无源分配点不是节点。
Computer network nodes
In data communication, a physical network node may either be a data communication equipment (DCE) such as a modem, hub, bridge or switch; or a data terminal equipment (DTE) such as a digital telephone handset, a printer or a host computer, for example a router, a workstation or a server.
在数据通信中，物理网络节点可以是数据通信设备（DCE），例如调制解调器，集线器，桥接器或交换机; 或诸如数字电话手机，打印机或主计算机（例如路由器，工作站或服务器）的数据终端设备（DTE）。
If the network in question is a LAN or WAN, every LAN or WAN node (that are at least data link layer devices) must have a MAC address, typically one for each network interface controller it possesses. Examples are computers, packet switches, xDSL modems (with Ethernet interface) and wireless LAN access points. Note that a hub constitutes a physical network node, but does not constitute a LAN network node, since a hubbed network logically is a bus network. Analogously, a repeater or PSTN modem (with serial interface) is a physical network node but not a LAN node in this sense.[2][clarification needed] 网络中的问题就是lan和wan If the network in question is the Internet or an Intranet, many physical network nodes are host computers, also known as Internet nodes, identified by an IP address, and all hosts are physical network nodes. However, some datalink layer devices such as switches, bridges and WLAN access points do not have an IP host address (except sometimes for administrative purposes), and are not considered to be Internet nodes or hosts, but as physical network nodes and LAN nodes.
看到这什么是mac_address?
MAC_address
A media access control address (MAC address) of a computer is a unique identifier assigned to network interfaces for communications at the data link layer of a network segment. MAC addresses are used as a network address for most IEEE 802 network technologies, including Ethernet and WiFi. Logically, MAC addresses are used in the media access control protocol sublayer of the OSI reference model. 计算机的介质访问控制地址（MAC地址）是分配给网络接口的唯一标识符，用于在网段的数据链路层进行通信。 MAC地址用作大多数IEEE 802网络技术的网络地址，包括以太网和WiFi。 逻辑上，MAC地址用在OSI参考模型的媒体访问控制协议子层中
MAC addresses are most often assigned by the manufacturer of a network interface controller (NIC) and are stored in its hardware, such as the card's read-only memory or some other firmware mechanism. If assigned by the manufacturer, a MAC address usually encodes the manufacturer's registered identification number and may be referred to as the burned-in address (BIA). It may also be known as an Ethernet hardware address (EHA), hardware address or physical address (not to be confused with a memory physical address). This can be contrasted to a programmed address, where the host device issues commands to the NIC to use an arbitrary address.
MAC地址最经常由网络接口控制器（NIC）的制造商分配并且存储在其硬件中，诸如卡只读存储器或一些其他固件机制.如果有制造商分配，
A network node may have multiple NICs and each NIC must have a unique MAC address. Sophisticated network equipment such as a multilayer switch or router may require one or more permanently assigned MAC addresses.
MAC addresses are formed according to the rules of one of three numbering name spaces managed by the Institute of Electrical and Electronics Engineers (IEEE): MAC-48, EUI-48, and EUI-64. The IEEE claims trademarks on the names EUI-48[1] and EUI-64,[2] in which EUI is an abbreviation for Extended Unique Identifier.
MAC（Media Access Control或者Medium Access Control）地址，意译为媒体访问控制，或称为物理地址、硬件地址，用来定义网络设备的位置。在OSI模型中，第三层网络层负责 IP地址，第二层数据链路层则负责 MAC地址。因此一个主机会有一个MAC地址，而每个网络位置会有一个专属于它的IP地址 MAC地址是网卡决定的，是固定的
网卡的物理地址通常是由网卡生产厂家烧入网卡的EPROM（一种闪存芯片，通常可以通过程序擦写），它存储的是传输数据时真正赖以标识发出数据的电脑和接收数据的主机的地址。
也就是说，在网络底层的物理传输过程中，是通过物理地址来识别主机的，它一定是全球唯一的。比如，著名的以太网卡，其物理地址是48bit（比特位）的整数，如：44-45-53-54-00-00,以机器可读的方式存入主机接口中。以太网地址管理机构(除了管这个外还管别的)（IEEE）（IEEE：电气和电子工程师协会）将以太网地址，也就是48比特的不同组合，分为若干独立的连续地址组，生产以太网网卡的厂家就购买其中一组，具体生产时，逐个将唯一地址赋予以太网卡。
形象地说，MAC地址就如同我们身份证上的身份证号码，具有全球唯一性。
Ethernet
Ethernet /ˈiːθərnɛt/ is a family of computer networking technologies commonly used in local area networks (LANs) and metropolitan area networks (MANs).[1] It was commercially introduced in 1980 and first standardized in 1983 as IEEE 802.3,[2] and has since been refined to support higher bit rates and longer link distances. Over time, Ethernet has largely replaced competing wired LAN technologies such as token ring, FDDI and ARCNET.
The original 10BASE5 Ethernet uses coaxial cable as a shared medium, while the newer Ethernet variants use twisted pair and fiber optic links in conjunction with hubs or switches. Over the course of its history, Ethernet data transfer rates have been increased from the original 2.94 megabits per second (Mbit/s)[3] to the latest 100 gigabits per second (Gbit/s). The Ethernet standards comprise several wiring and signaling variants of the OSI physical layer in use with Ethernet.
系统通过以太网通信将数据流划分称为帧的较短段，每个帧包含源和目的地址以及错误校验数据，使得可以检测和丢弃损坏的帧; 最常见的是，较高层协议触发丢失帧的重传
Systems communicating over Ethernet divide a stream of data into shorter pieces called frames. Each frame contains source and destination addresses, and error-checking data so that damaged frames can be detected and discarded; most often, higher-layer protocols trigger retransmission of lost frames. As per the OSI model, Ethernet provides services up to and including the data link layer.[4] Since its commercial release, Ethernet has retained a good degree of backward compatibility. Features such as the 48-bit MAC address and Ethernet frame format have influenced other networking protocols. The primary alternative for some uses of contemporary LANs is Wi-Fi, a wireless protocol standardized as IEEE 802.11.[5]
以太网(Ethernet)指的是由Xerox公司创建并由Xerox、Intel和DEC公司联合开发的基带局域网规范，是当今现有局域网采用的最通用的通信协议标准。以太网络使用CSMA/CD（载波监听多路访问及冲突检测）技术，并以10M/S的速率运行在多种类型的电缆上。以太网与IEEE802.3系列标准相类似 作者：马萧萧 链接：https://www.zhihu.com/question/19918493/answer/71953831 来源：知乎 著作权归作者所有，转载请联系作者获得授权。
以太网（英语：Ethernet）是为了实现局域网通信而设计的一种技术，它规定了包括物理层的连线、电子信号和介质访问层协议的内容。以太网是目前应用最普遍的局域网技术，取代了其他局域网标准如令牌环、FDDI和ARCNET。 互联网（英语：Internet）是一个网络的网络，它是由从地方到全球范围内几百万个私人的，政府的，学术界的，企业的和政府的网络所构成，通过电子，无线和光纤网络技术等等一系列广泛的技术联系在一起。 简单地说，以太网是一直为了实现局域网通信而设计的一系列方法，包括物理层传输媒介和CSMA/CD协议等内容，而互联网是计算机网络。 以太网（IEEE 802.3标准）是最常用的局域网组网方式。以太网使用双绞线作为传输媒介。在没有中继的情况下，最远可以覆盖200米的范围。最普及的以太网类型数据传输速率为100Mb/s，更新的标准则支持1000Mb/s和10000Mb/s的速率。 其他主要的局域网类型有令牌环和FDDI（光纤分布数字接口，IEEE 802.8）。令牌环网络采用同轴电缆作为传输媒介，具有更好的抗干扰性；但是网络结构不能很容易的改变。FDDI采用光纤传输，网络带宽大，适于用作连接多个局域网的骨干网。
Read-only memory
Read-only memory (ROM) is a type of non-volatile memory used in computers and other electronic devices. Data stored in ROM can only be modified slowly, with difficulty, or not at all, so it is mainly used to store firmware (software that is closely tied to specific hardware and unlikely to need frequent updates) or application software in plug-in cartridges.
只读存储器（ROM）是在计算机和其他电子设备中使用的一种非易失性存储器。存储在ROM中的数据只能缓慢地修改，有困难或根本不修改，因此它主要用于存储固件（与特定硬件密切相关的软件，不太可能需要频繁更新）或插入盒中的应用软件 。 网卡的物理地址通常是由网卡生产厂家烧入网卡的EPROM（一种闪存芯片，通常可以通过程序擦写），它存储的是传输数据时真正赖以标识发出数据的电脑和接收数据的主机的地址
Strictly, read-only memory refers to memory that is hard-wired, such as diode matrix and the later mask ROM (MROM) which cannot be changed after manufacture. Although discrete circuits can be altered in principle, integrated circuits (ICs) cannot, and are useless if the data is bad or requires an update. That such memory can never be changed is a disadvantage in many applications, as bugs and security issues cannot be fixed, and new features cannot be added.
More recently, ROM has come to include memory that is read-only in normal operation, but can still be reprogrammed in some way. Erasable programmable read-only memory (EPROM) and electrically erasable programmable read-only memory (EEPROM) can be erased and re-programmed, but usually this can only be done at relatively slow speeds, may require special equipment to achieve, and is typically only possible a certain number of times.[1]
Non-volatile memory
Non-volatile memory, nonvolatile memory, NVM or non-volatile storage is a type of computer memory that can retrieve stored information even after having been power cycled (turned off and back on). Examples of non-volatile memory include read-only memory, flash memory, ferroelectric RAM (F-RAM), most types of magnetic computer storage devices (e.g. hard disk drives, floppy disks, and magnetic tape), optical discs, and early computer storage methods such as paper tape and punched cards. Non-volatile memory is typically used for the task of secondary storage, or long-term persistent storage.[1] The most widely used form of primary storage today is a volatile form of random access memory (RAM), meaning that when the computer is shut down, anything contained in RAM is lost. However, most forms of non-volatile memory have limitations that make them unsuitable for use as primary storage. Typically, non-volatile memory costs more, provides lower performance, or has worse write endurance than volatile random access memory.
Non-volatile data storage can be categorized in electrically addressed systems (read-only memory) and mechanically addressed systems (hard disks, optical disc, magnetic tape, holographic memory, and such). Electrically addressed systems are expensive, but fast, whereas mechanically addressed systems have a low price per bit, but are slow. Non-volatile memory may one day eliminate the need for comparatively slow forms of secondary storage systems, which include hard disks.
Several companies are working on developing non-volatile memory systems comparable in speed and capacity to volatile RAM.
Network interface controller
A network interface controller (NIC, also known as a network interface card, network adapter, LAN adapter or physical network interface,[1] and by similar terms) is a computer hardware component that connects a computer to a computer network
网络接口控制器（NIC，也称为网络接口卡，网络适配器，LAN适配器或物理网络接口[1]以及类似术语）是将计算机连接到计算机网络的计算机硬件组件
Early network interface controllers were commonly implemented on expansion cards that plugged into a computer bus. The low cost and ubiquity of the Ethernet standard means that most newer computers have a network interface built into the motherboard.
早期的网络接口控制器通常在插入计算机总线的扩展卡上实现。 以太网标准的低成本和无处不在意味着大多数较新的计算机具有内置在主板中的网络接口。
看到这就对LAN和WAN想了解了~
LAN
A local area network (LAN) is a computer network that interconnects computers within a limited area such as a residence, school, laboratory, university campus or office building[1] and has its network equipment and interconnects locally managed. By contrast, a wide area network (WAN), not only covers a larger geographic distance, but also generally involves leased telecommunication circuits or Internet links. Ethernet and Wi-Fi are the two most common transmission technologies in use for local area networks. Historical technologies include ARCNET, Token ring, and AppleTalk.
局域网（LAN）是在有限的区域内互连计算机的计算机网络，例如住宅，学校，实验室，大学校园或办公大楼[1]，并且其网络设备和互连在本地管理。 相比之下，广域网（WAN）不仅覆盖更大的地理距离，而且通常涉及租用电信电路或互联网链路。
WAN
A wide area network (WAN) is a telecommunications network or computer network that extends over a large geographical distance. Wide area networks are often established with leased telecommunication circuits. Business, education and government entities use wide area networks to relay data among staff, students, clients, buyers, and suppliers from various geographical locations. In essence, this mode of telecommunication allows a business to effectively carry out its daily function regardless of location. The Internet may be considered a WAN.[1]
广域网（WAN）是在大的地理距离上延伸的电信网络或计算机网络。 通常使用租用电信电路建立广域网。
商业，教育和政府实体使用广域网络从不同地理位置的员工，学生，客户，买家和供应商之间传递数据。 实质上，这种通信模式允许企业有效地执行其日常功能，而不管位置如何。 互联网可以被认为是WAN。[1] 提出修改建议
A layer serves the layer above it and is served by the layer below it. For example, a layer that provides error-free communications across a network provides the path needed by applications above it, while it calls the next lower layer to send and receive packets that comprise the contents of that path. Two instances at the same layer are visualized as connected by a horizontal connection in that layer.
一个层服务它上面的层，并由它下面的层服务。 例如，提供跨越网络的无差错通信的层提供其上方的应用所需的路径，同时它调用下一较低层来发送和接收包括该路径的内容的分组。 在同一层的两个实例被可视化为通过该层中的水平连接来连接。