f******e 发帖数: 164 | 1 【 以下文字转载自 Linux 讨论区 】
发信人: francise (小飞猫), 信区: Linux
标 题: 问一个关于局域网的简单问题
发信站: BBS 未名空间站 (Thu May 1 01:47:09 2008)
当你把PC插上网线的时候,你的router怎么知道有一台机器联上来了呢?
我的意思是说,插上网线的时候,你的PC是不是立刻送了什么data给router?你的PC又
是怎么知道网线插上了呢? | z*****n 发帖数: 7639 | 2 Actually this is not simple question.
1. The physical layer sensing first starts to work:
When a transceiver(e.g., your PC's LAN card) is not connected (plugged in),
the transmitter output is open and giving infinite impedance (zero current),
when the port is connected to another transceiver such as a port of router.
The transmitter is connected to a receiver circuits thus the impedance is c
hanged. This change can be sensed by the transmitter circuits and as the res
ult, it marks a signal to Da
【在 f******e 的大作中提到】 : 【 以下文字转载自 Linux 讨论区 】 : 发信人: francise (小飞猫), 信区: Linux : 标 题: 问一个关于局域网的简单问题 : 发信站: BBS 未名空间站 (Thu May 1 01:47:09 2008) : 当你把PC插上网线的时候,你的router怎么知道有一台机器联上来了呢? : 我的意思是说,插上网线的时候,你的PC是不是立刻送了什么data给router?你的PC又 : 是怎么知道网线插上了呢?
| f******e 发帖数: 164 | | f******e 发帖数: 164 | 4 当一台电脑刚刚连入LAN的时候,他是先广播DHCP,这是并没有触发下一层的ARP,对么
?直到有了自己的IP之后,以后法的第一个包才需要ARP来解析目的IP,对么?
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【在 z*****n 的大作中提到】 : Actually this is not simple question. : 1. The physical layer sensing first starts to work: : When a transceiver(e.g., your PC's LAN card) is not connected (plugged in), : the transmitter output is open and giving infinite impedance (zero current), : when the port is connected to another transceiver such as a port of router. : The transmitter is connected to a receiver circuits thus the impedance is c : hanged. This change can be sensed by the transmitter circuits and as the res : ult, it marks a signal to Da
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