Knowledge requested: Netboot & PXE boot

[chris_kemp]

Wondering if any of you fine folks has had to navigate letting these two co-exist on the same network? What (technical) challenges did you run into? How did you solve it?

I have a meeting coming up with some higher-ups about this issue. I'm pulling for what we need to use Casper, but there have been parallel developments on the Windows side of things, so now we need to figure out how to meet in the middle. I'm somewhat versed in this subject, but I am not a network guru so anything that can be shared is appreciated.

One issue, which I'm still trying to figure out, is how using bless (via Casper Remote, or apparently even directly on the command line) could be subverted by the network settings or the DHCP server - even on the same subnet?

I thought that by declaring the netboot server address in the EFI we would be bypassing the broadcast request, which is being picked up (and mis-routed) by the DHCP service (confirmed by monitoring ports 67 and 68 with Wireshark while initiating BSDP request from Startup Disk.) Am I mistaken? Does the DHCP service have to accommodate the Netboot request?

For completeness, we're booting 10.7.5 clients to a 10.8.4 server (Mac Mini). Cross-subnet booting was, and still is, working on one network segment but several others are not.

[blackholemac]

I am observing what you are seeing with some clients working with cross - subnet booting and others aren't. I remember there was a post explaining that too. Something about newer Macs using slightly newer firmware that qualifying things with the bless command no longer seems to work.

I'm in the same pickle you are really though. Not much anyone here can do about it either until we migrate from our Nortel equipment to Cisco gear and work with IP Helper. To truly do it the "right way", I am told that all we need to do is add our NetBoot Server to IP Helper but make sure that we keep all forms of DHCP shut off on the NetBoot Server.

[chris_kemp]

We have been using IP Helper here without issue. It's ideal, but unfortunately there are places where this can't happen, and seem to be in conflict with other arrangements (the PXE boot setup, specifically).

There is something else going on here, though - the things I can't seem to figure:
1. machines on the SAME subnet not only failing to netboot via Casper, but not even able to see the image from a server that lives on that subnet?

1. Why this is affecting older Macs that were previously (and recently) imaged - they worked fine until they moved to the subnet in question. This is why I don't think firmware is the culprit, along with the fact that the newer machines are not THAT new, but the same vintage as machines I have here in Atlanta that netboot fine also, from the same image (different server).

This is weird...best suggestion I've heard so far is the possibility that the DHCP packet offering the boot file is somehow overwriting the info in the EFI. Possible?

[mscottblake]

I would also be very interested in more information on this subject. I currently don't even have a Netboot server running because the Windows guys started doing VDI. Since they have more machines and since the machines depend on it to run, they win.

It would be nice to know exactly what would need done to the network to make them coexist. I can't even test things because they are afraid of the effects my testing could have on the Windows boxes.

[chris_kemp]

Have a request into Apple Support for more information on Netboot and possible conflicts with PXE booting. If they can give me something relevant I'll post it here.

[bentoms]

I've used PXE & NetBoot in various environments across VLANs with no issues.

In fact, we added the NetBoot IP's to the needed sites IPHelper table within the past 2 years.

IPHelper is still working for PXE to SCCM or Altiris on those sites.

To ally the fears of the NW guys, we added the IP out of hours. Them tested the PXE & NetBooted clients & verified clients get IP's from DHCP still.

As the NW guy said, it'll take 5 minutes to test & less than that to roll back.

For more technical confidence, try & find the Bombich docs.

I think the clients 1st boot & ask the IPHelper IP's for DHCP, the BOOTP(NetBoot), the PXE. (Last 2 can be swapped).

If a server whose IP is in the IPHelper table but does not offer the service then the client skips it.

(Something like that anyways).

[RobertHammen]

I think you meant the Bombich docs - damn autocorrect.

Google "mike bombich netboot" for a ton of useful links/discussions.

[bentoms]

@ Robert... Already corrected!!

[chris_kemp]

Can you give me some more specific info about configuring the DHCP? If I can pass a full solution on to the Windows guys we might be able to take care of this in a way that makes everyone happy. If you prefer, you can reach me via email - chris (DOT) kemp (AT) turner (DOT) com.

[bentoms]

@ msblake... We also have 400 or so VDI clients put of 2,000 with 200 macs spread across 10 sites with Mac Mini's & IPHelper where more than 1 VLAN.

Working fine.

[chris_kemp]

A lot of the Bombich stuff seems to redirect to AFP548.com - but is returning 404 errors. :(

How many IPs can one put in an IP Helper table (Cisco switches?)

[bentoms]

@ Chris.. There is nothing to configure. It's just that your DHCP servers are typically in your IPHelper table.

The Mike Bombich docs better explain it.

[chris_kemp]

If I could find them I'd read them...been Googling stuff for days, but as I said the Bombich docs seem to be MIA, at least from the original sources.

[chris_kemp]

@ bentoms - To be clear, we have been setting IP Helper addresses here for a few years, and this works fine. It is changing, however - I'm getting pushback about Helper IPs, and I see that the PXE boot stuff is being served FROM the DHCP - that's what I was asking about, how might DHCP be configured to work with Netboot.

[bentoms]

http://web.archive.org/web/20081013124731/http://www.bombich.com/mactips/

Ah. Right then, I don't know how to answer your question.

I'm guessing PXE has some DHCP standard for forwarding on requests.

Sorry you're out of my depth now!

[chris_kemp]

Thanks for the link!

[Kumarasinghe]

In our environment (a Cisco network infrastructure), we used Cisco next-server command to configure the dhcp to do PXE and used ip helper-addresses for NetBoot.

[chris_kemp]

Thanks, I'll pass that along to our PXE guys. :)

More info about configuring DHCP for Netboot:
http://web-beta.archive.org/web/20071021180856/http://www.afp548.com/article.php?story=20061220102102611

[yadin]

Did folks ever get this working and if so how? What I never find in these threads is the magic sauce. PXE users DHCP client options 66 (server) and 67 (file) but no one ever seems to have mention of what options are needed for netboot. If these can work side by side what options does netboot use and what do they need to be set to? I haven't tried replacing these values with those of the netboot server, but then I have no idea what 67 would need to be, and I really don't want to replace the WDS settings, and by statements I see netboot would have it's own options and not take over the PXE ones.