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Question regarding PXE and IP helpers

    Question

  • I'm sorry if this has been asked before.  I've been reading a lot of stuff on PXE / IP helper and I'm just getting more confused.

    I have 3 secondary sites. The site servers in these sites will have PXE installed on them. These sites will services several boundaries (ip subnets).  Let's say a PC in a boundary serviced by Secondary site #1 does a PXE request (the PC is not in the same ip subnet as the site server/pxe server and must cross a router), will it be received by the PXE server. If not, is this why an IP helper is used for (to point it in the right direction)? If not, what do IP helpers do exactly?

    Can someone share their experiences with PXE/IP helper/multiple subnets and routers?

    Thanks,

    Jesmat.

    Tuesday, April 27, 2010 6:21 PM

Answers

  • PXE has nothing to do with your ConfigMgr hierarchy; it is a network protocol that is agnostic of the hardware initiating it or service hosting the server.

    PXE is a broadcast protocol that is nearly identical to DHCP and BOOTP; this means that the PXE packets will not cross routers. This is where the IP Helpers come in, they tell the router (or layer 3 device) to forward PXE/DHCP/BOOTP packets to a specific IP address. This allows the the broadcast packets to reach the PXE server which can then respond to the client with the PXE information (this is very similar to the DHCP process).


    Jason | http://myitforum.com/cs2/blogs/jsandys | http://blogs.catapultsystems.com/jsandys/default.aspx | Twitter @JasonSandys
    • Marked as answer by JesMat Wednesday, April 28, 2010 12:30 PM
    Tuesday, April 27, 2010 8:36 PM

All replies

  • PXE has nothing to do with your ConfigMgr hierarchy; it is a network protocol that is agnostic of the hardware initiating it or service hosting the server.

    PXE is a broadcast protocol that is nearly identical to DHCP and BOOTP; this means that the PXE packets will not cross routers. This is where the IP Helpers come in, they tell the router (or layer 3 device) to forward PXE/DHCP/BOOTP packets to a specific IP address. This allows the the broadcast packets to reach the PXE server which can then respond to the client with the PXE information (this is very similar to the DHCP process).


    Jason | http://myitforum.com/cs2/blogs/jsandys | http://blogs.catapultsystems.com/jsandys/default.aspx | Twitter @JasonSandys
    • Marked as answer by JesMat Wednesday, April 28, 2010 12:30 PM
    Tuesday, April 27, 2010 8:36 PM
  • Jason,

    Thank you...that's exactly what I wanted to know.

    Regards,

    Jesmat.

    Wednesday, April 28, 2010 12:30 PM
  • Thanks Jason,

    Your post was  a great help.  Here's a little more detail on how to:

    http://blogs.technet.com/b/adnanezzi/archive/2009/06/22/configmgr-2007-osd-how-to-allow-dhcp-broadcasts-across-vlan-s.aspx

    Tuesday, June 01, 2010 10:09 AM