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Multiple DHCP Servers and PXE

Posted on 2013-10-24
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Last Modified: 2013-11-11
I setup Ubuntu with Terminal Servers and trying to configure dumb terminals to access via PXE, but I have an existing DHCP Server which is taking preference over the PXE DHCP Server.
I have set the options on my Source DHCP but it is not taking preference. Please help.
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Question by:IBSIT
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6 Comments
 
LVL 28

Expert Comment

by:asavener
ID: 39601053
Two choices:

1) configure the other DHCP server to give out the PXE boot info.
2) configure your VLAN/broadcast domain so that only the DHCP you want is answering requests.
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Author Comment

by:IBSIT
ID: 39601130
I would like to configure the source DHCP to broadcast PXE but its not working
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by:vivigatt
ID: 39603216
You can't have 2 DHCP servers on the same subnet (unless they are configured for failover or scope splitting).
Now, you DON'T need a dhcp server running on the host that runs your PXE server.
You just use your standard DHCP server to assign IP config (address etc) and the PXE server to give "PXE" information (boot file name, tftp server IP address).
I've done that with dnsmasq under Ubuntu in the past:
I had an external DHCP server and dnsmasq was just the "PXE service" (aka ProxyDHCP).
I used this article as my main source for setting up dnsmasq as a ProxyDHCP service

https://help.ubuntu.com/community/UbuntuLTSP/ProxyDHCP
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Author Comment

by:IBSIT
ID: 39605754
is there a way to configure tftp server and boot file on the external DHCP Server?
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Expert Comment

by:asavener
ID: 39605825
It's just setting options on scope.  You need to be a DHCP admin, though.
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Accepted Solution

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vivigatt earned 500 total points
ID: 39614557
DON'T SET tftp and bootfile name directly in DHCP options (options 66 and 67) if you have a real PXE server serving these options.
A PXE server (aka proxyDHCP) is exactly made for that: sending tftp server IP address and bootfile name to clients (based on architecture and other criteria). If you set the same options in the DHCP server config, you create a conflict.

Check my article (and its comments) for more details:
http://www.experts-exchange.com/Networking/Misc/A_2978-PXEClient-what-is-it-for-Can-I-use-PXE-without-it.html

No, for your question
"is there a way to configure tftp server and boot file on the external DHCP Server? "
the answer is yes (actually, this is the role of a PXE server/ProxyDHCP server).
If you read the link I sent you previously, you will see that this is configured in dnsmasq config:
# The boot filename.
dhcp-boot=/ltsp/i386/pxelinux.0
you don't need to specify a tftp server address if the tftp daemon/Service runs on the same host that runs dnsmasq.
You can specify it as a dhcp 66 option, using this syntax in the .conf file:
dhcp-option=66,"192.168.1.2"
Quotes are required
(replace the IP address by the TFTP server IP address)
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