DHCP Behaviour


4 posts
by linker3000 » Sun Apr 29, 2012 12:40 pm
When my RPi's rebooted (Debian) its DHCP-assigned address tends to increment through the DHCP IP address pool – eg: if it's currently assigned 192.168.1.20, after a reboot it will be on 192.168.1.21.

I'm not over familiar with the DHCP mechanism, but is this behaviour due to the lack of a real-time clock on the RPi and so it cannot track DHCP lease/expiry times and thus make them persist across reboots?

Setting aside the use of fixed IP addresses or binding IPs to MAC addresses,  any chance of altering the RPI's DHCP behaviour as I can see this causing issues in classrooms where the IP pool is quickly exhausted and also students losing track of their boards.
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by SN » Sun Apr 29, 2012 1:12 pm
thats an interesting one - assuming the lease's are very short on the DHCP server should not be a problem though
Steve N – binatone mk4->intellivision->zx81->spectrum->cbm64->cpc6128->520stfm->pc->raspi ?
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by nimdy » Sun Apr 29, 2012 1:15 pm
I've been using mine for a couple of weeks now, and the Pi always gets the same IP from the DHCP router. Maybe this is just how my router is configured.
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by linker3000 » Sun Apr 29, 2012 1:18 pm
SN: I considered short leases (actually, I have bound an IP to the RPI's MAC address), but that would still mean having to chase your RPi around - and in a class of students all rebooting that could be fun!

Nimdy: Interesting, maybe it depends on the DHCP server - mine's currently a Draytek 2820 ADSL router.
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