DHCP: renewal when cable is plugged out/in

Chris Caudle chris at chriscaudle.org
Fri Apr 4 16:36:59 UTC 2008

On Fri, April 4, 2008 4:40 am, Arnout Vandecappelle wrote:
>  Actually also on my laptop it would be useful: I sometimes move to the
> meeting room, which is on a separately routed network, so my IP address
> should be updated...  But that's of no concern on this forum :-)

Perhaps the solutions are similar.  On a Windows laptop, the easiest
solution to the problem is to run "ipconfig /renew" to renew the IP
address for the interface, which seems to cause a new request to the DHCP
server. I would assume that the /renew argument is an implicit call to
/release first to release the current IP address, then a new request to
have an address assigned.

I'm not sure what the equivalent on posix systems is, my Linux systems are
not portable, so I don't usually have need to acquire an address outside
of the normal lease cycle.  I think maybe a SIGHUP to the dhcpc daemon,
and restarting the daemon.

I'm not familiar with how all the equivalent functions are integrated into
RTEMS, so I can't offer specific suggestions, but maybe this will prompt
some thought.  Perhaps there is a way for the application on RTEMS to
detect the Ethernet interface going down then up again, and send a signal
to cause the DHCP client to do the equivalent of release and renew?

Chris Caudle

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