当我们在网络上连接以太网设备时，它以什么速度开始通信
以太网设备连接到 an/w 执行哪些步骤？ 它是从支持的最低速度还是最高速度开始通信？
为了更清楚地说明这一点，我有以下示例：
如果设备 A 当前设置为 10Mbps，并且仅连接到 N/W 路由器 R，则它可以支持 10Mbps 和 100Mbps。哪个设备（A 或 R）将首先进行通信以及速度。如果是设备A，路由器如何了解设备A发送的传输速度？
What steps are performed by ethernet device to connect to a n/w?
Does it start communication from it's lowest or highest supported speed?
To make it more clear I have following example
If device A is currently setup at 10Mbps and just connected to N/W router R,which can support both 10Mbps and 100Mbps. Which device(A or R) will communicate first and what speed. If device A, how will router understand the speed of transmission send by device A?
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您似乎在询问以太网自动协商 - IEEE 802.3ab；在自动协商 1Gbps 链路时，自动协商应该实现这组优先级...
哪个设备首先传送自动协商脉冲并不重要；最重要的是，IEEE 为它们定义了一个非常具体的时间窗口来完成自动协商。
设备是否能够真正以这些速度进行链接取决于两个以太网 PHY 是否支持所述模式，以及通道（即布线）是否具有足够的电气带宽容量...每个 PHY 将进行信噪比测试，以确定通道是否支持足够的容量来满足所需的速度。
阅读此以太网 PHY 应用说明（美国国家半导体）可能会很无聊，或者是否充满兴奋取决于你对实现细节的容忍度。
You seem to be asking about ethernet autonegotiation - IEEE 802.3ab; Autonegotiation should implement this set of priorities when autonegotiating a 1Gbps link...
It doesn't matter which device communicates autonegotiation pulses first; the bottom line is that IEEE defines a very specific time window for both of them to finish autonegotiation.
Whether a device can actually link at these speeds depends on whether both ethernet PHYs support said mode, and whether the channel (i.e. wiring) has sufficient electrical bandwidth capacity... each PHY will conduct a signal to noise ratio test to determine whether the channel supports enough capacity for the desired speed.
Reading this Ethernet PHY application note (National Semiconductor) may be boring, or full of excitement depending on your tolerance for implementation details.