On Fri, Jan 16, 2009 at 09:46:35PM +0000, mbm wrote:
On Fri, 16 Jan 2009 21:09:28 +0000 Chris G cl@isbd.net allegedly wrote:
I think you're right though I don't *quite* understand exactly why the router did what it did. It was actually trivial to fix because the newly installed machine has two built in LAN connections, simply plugging the ethernet connection into the other one sorted everything and it got the expected address of 192.168.1.65.
As you say the machine *used* to be 192.168.1.4 and the router had remembered its MAC address and assigned it. Surely though the router should have been 'bright enough' to realise the MAC address had been re-assigned.
Sorry - I don't understand that. The only information the DHCP server had was the request and the MAC address requesting the lease. I'm not sure how you expect the router the know that that MAC address had somehow been "re-used" and now needed a new IP address.
Well, because the IP address that *had* been assigned to that MAC address is already in use. The router has never assigned 192.168.1.4 itself, it has always been set to start giving out addresses from 192.168.1.64 upwards. I really don't see why it needs to even attempt to 'assign' addresses below 192.168.1.64, all the addresses below that are cast in stone elsewhere.
I still can't see where in the router to tell it not to remember MAC addresses and assign the same IP addresses to them.
Keep searching. If this is a domestic grade router, then somewhere there will be an option in the DHCP configuration something like "always assign the same IP address". Simply uncheck that option.
It a Draytek Vigor 2820n. The DHCP setup has:-
DHCP Server Configuration Enable Server Disable Server Relay Agent: 1st Subnet 2nd Subnet Start IP Address IP Pool Counts Gateway IP Address DHCP Server IP Address for Relay Agent
.... aaaaahhhhhhhhh!!!!!
There's a separate setup for "Bind IP to MAC", that's where it's remembered the old system's MAC address.
OK, both sorted *and* understood now! :-)