Further down that same section it restates the same point along with the reasons why:
If you configure these options, client computers will receive an IP address lease, information about the boot server, and information about the NBP directly from the DHCP server. Clients will not contact the Windows Deployment Services server by using DHCP, but they will download the NBP through Trivial File Transfer Protocol (TFTP) on UDP port 4011. Microsoft does not recommend this method for the following reasons: * Using DHCP options is not as reliable as configuring a router. In testing, clients have incorrectly parsed the DHCP options that were returned from the DHCP server and as a result, the client received a "TFTP Failed" error message. Generally, this problem occurs when the PXE ROM ignores the boot server host name and attempts to download the NBP directly from the DHCP server. * If there are multiple Windows Deployment Services servers available to service client requests, specifying a specific server may prevent load-balancing. In contrast, using router forwarding tables you can forward the request to multiple servers. * Clients may be directed to a Windows Deployment Services server that is not available. Because the client does not have to contact a Windows Deployment Services server directly to determine the NBP to download, the DHCP server may direct clients to download a NBP that does not exist or to a server that is not currently available. * Clients may bypass the Windows Deployment Services server's answer settings. From: [email protected] [mailto:[email protected]] On Behalf Of Justin Chalfant Sent: Friday, September 19, 2014 12:52 PM To: [email protected] Subject: RE: [mssms] ConfigMgr 2012 R2 OSD + PXE :: IP Helper vs. DHCP Options Here's a good post from Microsoft about the two: http://technet.microsoft.com/en-us/library/cc732351(WS.10).aspx Using DHCP Options 60, 66, and 67<javascript:void(0)> ________________________________ Although Microsoft does not recommend this method, you can use the following DHCP options to direct PXE clients to an appropriate NBP to download: * Option 60 = client identifier. You should set this to the string PXEClient. Note that this only applies if DHCP is on the same server as Windows Deployment Services. * Option 66 = boot server host name * Option 67 = boot file name Thanks, Justin Chalfant Premier Field Engineer - Configuration Manager Public Sector Microsoft Services Tel : (303) 846-2701 Email: [email protected]<mailto:[email protected]> If you have any feedback about my work, please let either myself or my manager Ron Hill know at [email protected]<mailto:[email protected]> From: [email protected]<mailto:[email protected]> [mailto:[email protected]] On Behalf Of Mote, Todd Sent: Friday, September 19, 2014 10:06 AM To: [email protected]<mailto:[email protected]> Subject: RE: [mssms] ConfigMgr 2012 R2 OSD + PXE :: IP Helper vs. DHCP Options It was that way, we even had MS on site in 2006 when WDS and Vista were still baking and 66 and 67 were viable options then. In fact we've been using 66 and 67 since then with great success. As far as I know we haven't gotten to UEFI yet. We have more than one DHCP service that point PXE requests to a variety of different end points, WDS, SCCM, or Cobbler, using options 66 and 67. We do not set option 60. From: [email protected]<mailto:[email protected]> [mailto:[email protected]] On Behalf Of Marcum, John Sent: Friday, September 19, 2014 10:13 AM To: [email protected]<mailto:[email protected]> Subject: RE: [mssms] ConfigMgr 2012 R2 OSD + PXE :: IP Helper vs. DHCP Options Sorry Jason. That must have changed. I actually went out looking for it AFTER I said that and to my surprise couldn't find it. Not even in the 2007 docs which I am POSITIVE at one time reccomdned options 60 and 67. That's what created all of this confusion to begin with. It was in the docs so people thought they should do it. However in practice it rarely worked. From: [email protected]<mailto:[email protected]> [mailto:[email protected]] On Behalf Of Jason Wallace Sent: Friday, September 19, 2014 10:10 AM To: [email protected]<mailto:[email protected]> Subject: RE: [mssms] ConfigMgr 2012 R2 OSD + PXE :: IP Helper vs. DHCP Options John Thank you for correcting me on the support level of DHCP options. I suspect John that as an MVP you will have access to the documentation which states "Furthermore the use of DHCP Options to control PXE requests in Configuration Manager 2012 is not supported by Microsoft. Therefore the recommended and supported method of PXE booting client PCs that are on a different subnet than the DHCP or WDS/PXE Service Point servers is the use of IP Helpers." I happened to be reviewing the document yesterday and the words "not supported by Microsoft" struck me I suppose that you could argue that were you to have an environment running WDS on Server 2008 where you never had any UEFI involvement then yes, Microsoft would support you. I am quite sure that regardless of the above I am sure that you would still be supported since we all know that "not supported" actually means "not tested" Jason ________________________________ From: [email protected]<mailto:[email protected]> To: [email protected]<mailto:[email protected]> Subject: RE: [mssms] ConfigMgr 2012 R2 OSD + PXE :: IP Helper vs. DHCP Options Date: Fri, 19 Sep 2014 14:18:24 +0000 Supported or not supported (by Microsoft) doesn't really matter here though because Microsoft products have nothing to do with most of the PXE process - it's almost entirely in the hands of the NIC to do the right thing. If something truly breaks down, it's either the NIC's fault or the network's. The DHCP server can play a small role here, but ultimately, that role is truly insignificant as it's still up to the NIC to determine what to do and then to do it. If the NIC does the wrong thing, there is no way to really troubleshoot it either and your only real recourse is to call the NIC vendor. There are NICs out there that some of us have encountered that simply refuse to do the right thing - these are pretty rare now days, but they do exist. With iphelpers, you simply have to watch the traffic if something weird is going on because it's not up to the NIC anymore. Experience has shown that iphelpers simply work better and as pointed out, with UEFI and architecture restrictions, DHCP cannot get the job done because it can only handle a single architecture. J From: [email protected]<mailto:[email protected]> [mailto:[email protected]] On Behalf Of Marcum, John Sent: Friday, September 19, 2014 7:13 AM To: [email protected]<mailto:[email protected]> Subject: RE: [mssms] ConfigMgr 2012 R2 OSD + PXE :: IP Helper vs. DHCP Options DHCP options are supported. From: [email protected]<mailto:[email protected]> [mailto:[email protected]] On Behalf Of Jason Wallace Sent: Thursday, September 18, 2014 6:20 PM To: [email protected]<mailto:[email protected]> Subject: Re: [mssms] ConfigMgr 2012 R2 OSD + PXE :: IP Helper vs. DHCP Options IP helpers is supported and recommended. DHCP is not and is not On 19 Sep 2014, at 00:14, Trevor Sullivan <[email protected]<mailto:[email protected]>> wrote: Over the past years that I have worked with Configuration Manager, I have learned to use IP helpers instead of DHCP options, to point client systems to a Windows Deployment Services (WDS) / PXE service. I have personally experienced multiple instances at customer sites, just over the past year, where DHCP options have simply not worked as expected, and caused erroneous error messages during PXE boot. As soon as we implement IP helpers, everything "just works." I am interested in gathering feedback from people on this mailing list to confirm or deny my current understanding on this topic. Do you use DHCP options or IP helper to point clients to the WDS/PXE service? Have you had a negative experience using one or the other? Cheers, Trevor Sullivan Microsoft PowerShell MVP <image001.png><http://mms.mnscug.org/> ________________________________ Confidentiality Notice: This e-mail is from a law firm and may be protected by the attorney-client or work product privileges. If you have received this message in error, please notify the sender by replying to this e-mail and then delete it from your computer. ________________________________ Confidentiality Notice: This e-mail is from a law firm and may be protected by the attorney-client or work product privileges. If you have received this message in error, please notify the sender by replying to this e-mail and then delete it from your computer. ________________________________ Confidentiality Notice: This e-mail is from a law firm and may be protected by the attorney-client or work product privileges. If you have received this message in error, please notify the sender by replying to this e-mail and then delete it from your computer. ________________________________ Confidentiality Notice: This e-mail is from a law firm and may be protected by the attorney-client or work product privileges. If you have received this message in error, please notify the sender by replying to this e-mail and then delete it from your computer.
