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Renold Singh
Asked: 2018-01-10 00:57:49 +0800 CST

Does a DHCP client is expected to send DHCP request unicast to the Server in the event of a Unplug/replug or eth0 down and up?

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I would like to understand if the DHCP client running in our embedded device is expected to send DHCP request unicasted to the server in the following events?

  1. Eth0 goes down and comes back online
  2. Physically Unplugging the ethernet cable.

As per a normal dhcp client running in the Windows 10 machine,It does send the unicast message in the event of unplug and disable/enable the interface.However the RFC 2131 doesn't explicitly states the behaviour? Or I missed some points in the RFC??

linux

1 Answers

  1. In case of a down/up it won't send unless it timesout. However, in case of a cable unplugged and then plugged again it will, since is alters the state of the physical connection which in turn triggers the request.

    Don't know if you've noticed, but when you do an ifconfig ethx down and then up, it has the ip address already configured, it never releases the lease unless you do a network restart, then it will request.

    home this helps

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