Re: dhcp/bonding interaction question

Jay Vosburgh wrote:

Chris Friesen [off-list ref] wrote:

quoted

On the
booting blade the xid in the packet doesn't match the xid for the device
on which the packet was received, so the packet is dropped.

	Presumably the blade is matching xid on a per-interface basis.

Yes, the dhcp code in the kernel does this.

	I'm guessing your problem is really due to the nature of the
intra-chassis network on the blade system.  If it's like the ones I'm
familiar with (eth0 of all blades to a single switch, eth1 of all blades
to a different switch, etc), then you can't configure the switches into
an etherchannel group as can be done with the usual configuration
(multiple ports on one switch).

This has been handled already.  The two switches are a single 
etherchannel group and all blades (except the booting one) have 
etherchannel enabled.

quoted

What's the proper solution here?  Should dhcpd be forcing reply packets
out the slave on which the packet was received?

	Why is the blade issuing DHCP before the bond is configured?

The blade is net-booting.  The BIOS does DHCP to download the kernel, 
and this works.  The kernel comes up and does DHCP to obtain an IP 
address so it can download the boot image, and this fails as described.

The etherchannel/bond link isn't set up until userspace is loaded and 
the bonding driver is insmodded (under multiple aliases with different 
sets of slaves).

I'm unsure as to whether dhcpd should force replies as suggested, but
recent changes to bonding/net core would probably permit dhcpd to run
directly on the slave (it might need tweaking, I'm not sure) and
accomplish that result. I don't think it would work on older versions
of bonding, since there's no way to tell which slave a packet arrived
on.

That's not a problem.  We've got an older version, but support for 
querying which slave a packet arrived on has been added.

Chris