Coexistence of Altiris and SCCM PXE Servers Within The Same Network

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The question is: Is it possible to have an Altiris and an SCCM PXE server within the same network with the target to serve some clients with Altiris and others with SCCM?

The answer is: Yes, but not easy.

The problem is that both systems are sending out custom bootstrap files that have to APIs to hook on. The Altiris server sends out a bootstrap file which ships a gui. The gui then shows a selection menu containing the available bootstrap images. The SCCM server does something quite similar. It sends out a bootstrap file, which detects the target clients architecture (wdsnbp) and then proceeds with an appropriate second bootstrap file.

Thus, what you have to do is to take over control on the FIRST DHCP offer sent to the client.

To accomplish this, you need some sort of decision engine. Technically there are some options:

Option 1: DHCP as decision engine:

You could use DHCP options 66+67 as PXE-referrals if you are able to change them in a dynamic manner based on MAC-addresses. To accomplish this, you would need to import all machines from SCCM and Altiris databases into a new DHCP database. Then, on every DHCP Discover request, you would query the DHCP database for the MAC address and answer the client with the correct DHCP options pointing the client to the appropriate PXE server – either SCCM or Altiris. This contruct requires network programming skills when it comes to use dynamic DHCP options. I’ve implemented it once with a colleague and I can say – it works! It was a custom network daemon attached to a Linux DHCP…

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Option 2: Split the clients into dedicated vlans:

Well, this is easy. And it’ll work because DHCP and PXE offer do not need to come from the same machine.

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Option 3: Control the PXE server reply behaviour.

If SCCM 2007 does not know a client machine (and does not support unknown computers), it does not send out an DHCP offer. I’m not sure if Altiris supports the same behaviour, but it should. In this scenario, you need to prestage all clients EITHER to Altiris OR to SCCM. Then, on a client boot, the client will query the DHCP and both PXEs and will only get an DHCP offer from the correct PXE server. It is absolutely crucial that you do NOT configure DHCP options in this scenario. If you would, then the DHCP would always answer. I’ve one customer who has implemented this by using two independent SCCM servers.

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