How to release a Dynamic IP address

[Gavin Li <bsdlist_(_at_)_yahoo_(_dot_)_com>]

I have a gateway at home which connects to Rogers DHCP
server. I want to release that IP address for the
external NIC. In linux, I can do "ifdown eth0". In
windown, I can do "ipconfig /release". In the OBSD I
found the ifconfig can mark a NIC down, put it doesn't
release the IP address because after I do " ifconfig
lx0 down" I do "Ifconfig -a" and I found the xl0 is
still active. Which means I can't use the other PC to
get IP address.
How can I release this IP address and recall an IP
address in the future?
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