iPXE discussion forum

Hi There,

I have come across an intersting problem when booting a client using ipxe/wds pxeboot.com. Basically I have a windows nlb ip address setup on this vlan and the ipaddress has a multicast MAC address.

As soon as bootmgr begins the tftp download of the .wim image my client starts happily responding to the multicast icmp packets that are arriving on its interface. Things are fine either side of the tftp download - so at the windows boot manager image chooser and once the .wim is booting all is well.

I've attached a .jpg showing a client pinging an nlb ip address - this is a multicast MAC address. when the ipxe client starts a tftp download of the .wim, this ipxe client starts responding to icmp ping requests arriving on its interface.

Has anybody seen anything like this before?

Regards

Murray

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oh yes, my network is a /16 so those 10.1 addresses are all in the same vlan.

Not familiar with NLB and multicast MAC addresses. Would you care to point to some docs or give a brief explanation?

Does the same thing happen if you use wimboot to load the .wim file?

Hi There,

bits 1 & 2 of the first octet of a mac address define unicast/multicast and hardware/locally administrered.
http://en.wikipedia.org/wiki/MAC_address...ss_details

this problem only occurs when ipxe has chainloaded wdsnbp.com and bootmgr is downloading a .wim image to boot. In my case where I absolutely need to fail back and boot a host via wds I have a menu option for this:
chain tftp://${wdsserver}/boot%5Cx86%5Cwdsnbp.com

during this time, any packets with the multicast bit set that hit the interface of the client are responded to - so the client is responding to an icmp packet where the destintion address isnt its own.

wimboot does not exhibit this behaviour. Oddly enough, native wds clients in the process of downloading an image do not respond to icmp requests either - it is just the combination of ipxe/wds.

(2013-09-01 15:26)robinsmidsrod Wrote: [ -> ]Not familiar with NLB and multicast MAC addresses. Would you care to point to some docs or give a brief explanation?

Does the same thing happen if you use wimboot to load the .wim file?