What's up with making DHCP reservations based on MAC addresses? I'm using the client-identifier command after setting the host ip in the dhcp pool, and prepending an 01 to the MAC address I see for the interface of a machine (say a Linux one). I noticed it got an address for a bit but then it eventually got some other dynamic address the next day.
Like I set it the following way
ip dhcp pool ubuntu_host
host 172.16.20.2 255.255.255.0
client-identifier 0100.187d.ff78.89
I clear the existing previous binding, bring the interface down and back up on the host, and notice the .2 works for a while.
But then later I see it has an IP of 172.16.20.3 in the dhcp binding table (which is what is actually present when doing an ifconfig on the host machine), and is only listed under the hardware address, without the initial 01 (although there is also still a a separate, non-active binding of 172.16.20.2 with the client identifier that shows 'Infinite').
So now I removed the reservation pool and recreated it with the hardware address (just MAC, without the 01). And so far for a little while it seems to work.
I guess my question is, what determines whether something will take a client identifier or a hardware address? Is it just different for potentially every machine? Not sure what's going on here... it seemed to accept the client id at first but then later preferred the hardware address? I also noticed similar situations for a few other reserved addresses. It's going to be a hassle having to figure out which works best for each one.
