Re: 6.0.1 upgrade dhcp problem

[Roy Marples <roy%marples.name@localhost>]

Hi Ray

I'm not subbed to this list, so include me directly on any replies.

You problem is two fold
1) dhclient is accepting a DHCP reply from 192.168.36.24 and dhcpcd is 
ignoring it and accepting a reply from 192.168.36.1
2) dhcpcd is doing something that makes the link unstable for ~30 
seconds

So, some answers:
1) dhcpcd rejects DHCP messages without a ServerID option.
To be conformant, a ServerID is required and several "rogue" DHCP 
servers don't include this option so by default it's blacklisted in 
dhcpcd.conf(5)
You can remove the "require dhcp_server_identifier" line in 
/etc/dhcpcd.conf to test

2) dhcpcd requests what MTU we should use on the network
dhclient does not do this either by default, and nor does the default 
script do anything useful with the value anyway.
dhcpcd on the other hand does request the MTU by default and does do 
something useful with it.
However, some drivers incorrectly reset PHY on a MTU change which 
triggers the link down/up and kind of gets into a little loop.
You can call `dhcpcd --nohook mtu fxp0`
If that works fine, inspect the DHCP message easily like so

dhcpcd -U fxp0

You should see the MTU value your DHCP server wants in the output.
If this makes it work for you then we really need to fix fxp(4).

Thanks

Roy