Re: dhcpd with multiple interfaces.

From: Cameron Kerr (cameron.kerr_at_paradise.net.nz)
Date: 04/13/04


Date: 14 Apr 2004 10:34:22 +1300

Eksa <ergy_78@hotmail.com> wrote:
> Cameron Kerr <cameron.kerr@paradise.net.nz> wrote in message
> news:<407499a4@news.maxnet.co.nz>...
>>
>> Perhaps you should show us the guts of your config file.
>
> Okay, here they come.
>
> Access points are connected to these interfaces: eth2 inet
> addr:192.168.1.65 Bcast:192.168.1.191 Mask:255.255.255.192 eth3 inet
> addr:192.168.1.129 Bcast:192.168.1.191 Mask:255.255.255.192

Well that's just silly. The broadcast address should be different for
each subnet.

$ ipsc -a 192.168.1.65/255.255.255.192
Network address: 192.168.1.64
Full subnet mask: 255.255.255.192

Subnet 1: 192.168.1.0 192.168.1.63
Subnet 2: 192.168.1.64 192.168.1.127 *
Subnet 3: 192.168.1.128 192.168.1.191
Subnet 4: 192.168.1.192 192.168.1.255

IP address: 192.168.1.65
Host allocation range: 192.168.1.65 - 192.168.1.126
Full subnet mask: 255.255.255.192

So the broadcast address assigned to eth2 should be 192.168.1.127.
eth3 should have 192.168.1.191

> option domain-name-servers 192.168.1.2

It is better to specify this on a per-subnet (interface) basis. Usually.

> subnet 192.168.1.64 netmask 255.255.255.192 {
> authoritative;
> option subnet-mask 255.255.255.192;
> option broadcast-address 192.168.1.127;

Ah, so you do have that right. Is it right on the server?

> So, here the client changes from AP1 (eth2) to AP2 (eth3). After a
> some kind of timeout the client sends DHCPDISCOVERY message and
> everything works fine. However, this break is something like one
> minute. I think that there is some kind of bug in DHCP server, since
> it really should NAK the DHCPREQUEST received via eth3, but it keeps
> ACK:ing...

I concur. But I would suggest that you try to replicate the problem
using just plain ethernet befare ruling it as a bug with DHCPd.

-- 
Cameron Kerr
cameron.kerr@paradise.net.nz : http://nzgeeks.org/cameron/
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