Cisco IOS DHCP and PXE boot

bavingtonm · ‎08-11-2008

Hi

I have cisco IOS DHCP server configured on a 2960G switch on Vlan 20. I have added a "IP helper-address" on the SVI of the switch for our Ghost server which is on a different subnet (Vlan 70) to the switch. I'm trying to do a PXE Boot to the ghost server but the hosts on Vlan 20 do not get assigned an IP from the switch when it is doing the PXE boot.

Can you please give me some advise on why this is not happening and please help me with the config?

Many thanks

Mark

chris.mcgill · ‎08-11-2008

Hi,

1. Remove the IP helper address. PXE clients send an Option 60 in the DORA process to identify themselves as PXE clients. Your DHCP then points them to the location of a PXE server (Ghost). You can set this up on the IOS DHCP server as below.

2. ip dhcp pool VLAN20

network x.x.x.x x.x.x.x

option 60 ip x.x.x.x

This will assign client the normal IP address, and if Option 60 is determined will tell them them the address of the Ghost server.

Thanks

chris.mcgill · ‎08-11-2008

Additional Options Available:

Option 66 will contain the ip or FQDN of your WDS server (PXE Service Point role in SCCM)

Option 67 will contain the name of your bootfile (SMSBoot\x86\wdsnbp.com)

tdavis85 · ‎04-25-2023

I had this same issue and tried the options, but what fixed it for me was adding the next-server command on the DHCP pool instead of using the ip helper on the SVI. Everything I've always read said to use the ip helper but how I was able to get it to work is to set the
next-server (PXE server address and DP address)

option 60 ascii "PXEClient"

Adding those two commands to the DHCP scope fixed it for me. I know this is an old thread but hopefully it helps others in the future.

Richard Burts · ‎04-26-2023

Yes it is an old discussion which does contain helpful information. Thanks for sharing your experience and adaptation of the solution.

HTH

Rick