网络拓扑 令牌环网 以太网

A topology explains how physically the network is designed or what is the structure of the network. These designs are both physical and logical. There are many network topologies 4 like Bus, Star, Ring, and Mesh. But only two types of topologies are used in Ethernet i.e Bus and Star. So, let's know about these two topologies:

拓扑结构说明了网络的物理设计方式或网络的结构。 这些设计是物理的和逻辑的。 有许多网络拓扑4，如Bus，Star，Ring和Mesh。 但是以太网中仅使用两种类型的拓扑，即总线和星形。 因此，让我们了解以下两种拓扑：

1) Bus Topology

1)总线拓扑

All computers in a bus topology are connected to a wire. Whenever a computer sends a computer frame, it goes to all the computers available in the topology, but it only accepts the computer whose MAC address matches the frame.

总线拓扑中的所有计算机都连接到电线。 每当计算机发送计算机框架时，它将转到拓扑中可用的所有计算机，但仅接受MAC地址与框架匹配的计算机。

The biggest disadvantage of bus topology is that if the wire ever gets damaged, then communication of all computers stops simultaneously. Computers have no means of communication separately from each other.

总线拓扑的最大缺点是，如果电线损坏，则所有计算机的通信将同时停止。 计算机没有彼此分开的通讯方式。

2) Star Topology

2)星型拓扑

All hosts in Star Topology are connected to a switch or hub and they send frames to each other through hosts hubs and switches. Hubs are not intelligent. When frames are sent through the hub, the hub sends those frames to all the hosts and the host that receives the MAC address matches it.

星型拓扑中的所有主机都连接到交换机或集线器，它们通过主机集线器和交换机相互发送帧。 集线器不是智能的。 当通过集线器发送帧时，集线器会将那些帧发送到所有主机，并且接收到MAC地址的主机将与之匹配。

Switches are intelligent devices. The switches maintain the address table of all hosts. So whenever a host sends a frame, it is not sent to everyone and goes to the same host whose MAC address matches. The biggest disadvantage of the star topology is that if the switch or hub spreads, all the networks fail.

开关是智能设备。 交换机维护所有主机的地址表。 因此，每当主机发送帧时，它都不会发送给每个人，而是转到其MAC地址匹配的同一主机。 星型拓扑的最大缺点是，如果交换机或集线器扩展，则所有网络都将发生故障。

以太网帧 (Ethernet Frame)

Ethernet data link layer technology. In the data link layer, the data is known as frames. The size of a frame can be from 64 bytes to 1522 bytes. There are some fields in the frame whose size is fixed. The information about these fields is given below.

以太网数据链路层技术。 在数据链路层中，数据称为帧。 帧的大小可以从64字节到1522字节。 框架中的某些字段的大小是固定的。 这些字段的信息在下面给出。

Preamble

前言

The size of this field is 7 bytes. This field is used for synchronization purpose.

该字段的大小为7个字节。 该字段用于同步目的。

Start of Frame

帧开始

The size of this field is 1 byte. This field shows the starting point of the frame.

该字段的大小为1个字节。 此字段显示帧的起点。

Destination MAC Address

目的MAC地址

The size of this field is 6 bytes. This field holds the destination host's MAC address.

该字段的大小为6个字节。 此字段保存目标主机的MAC地址。

Source MAC Address

源MAC地址

The size of this field is also 6 bytes. This field source hosts the MAC address.

该字段的大小也是6个字节。 该字段源托管MAC地址。

802. 1Q Tag

802. 1Q标签

The size of this field is 4 bytes. This field is optional. This tag is used to show VLAN configuration.

该字段的大小为4个字节。 该字段是可选的。 此标记用于显示VLAN配置。

Length

长度

The size of this field is 2 bytes. This field shows the size of the whole frame.

该字段的大小为2个字节。 此字段显示整个帧的大小。

Payload

有效载荷

The size of this field can be from 42 bytes to 1500 bytes. This is your actual data.

该字段的大小可以从42字节到1500字节。 这是您的实际数据。

CRC (Cyclic Redundancy Check)

CRC(循环冗余校验)

The size of this field is 4 bytes. This shows the errors in the field frame.

该字段的大小为4个字节。 这显示了字段框架中的错误。

Inter-Frame Gap

帧间间隙

The size of this field is 12 bytes. It shows the time gap between field frames.

该字段的大小为12个字节。 它显示了场帧之间的时间间隔。

翻译自: https://www.includehelp.com/computer-networks/types-of-network-topology-in-ethernet-connection-and-its-frame.aspx

网络拓扑 令牌环网 以太网