DHCP snooping and PXE issue

[marteraam]

I am trying to make PXE boot work with DHCP Snooping being enable on  blade switch

On PXE Clinet host I am receiving -> PXE-M0F: Exiting Intel Boot Agent Message. No boot device found.

I have injected PXE server IP address in the DHCP option.

I attached debug logs in the file.

Could you guide me if DHCP snooping could block PXE?

[Peter Paluch]

Hi,

The debug log does not seem to contain any traces of your DHCP Snooping blocking PXE. The entire sequence of DISCOVER/OFFER/REQUEST/ACK seems to have been carried between your PXE client and DHCP server just fine.

May I ask you to explain your environment a little closer?

1. The debugs suggest that either the PXE client or the DHCP server are somewhere in VLANs 50 or 60. Can you be more specific about their VLAN membership?
2. Would a normal client in place of the PXE client receive an IP address?
3. Also, if the PXE client was moved into the same VLAN as the DHCP server, would it be able to receive its IP address?
4. Lastly, if possible, would it be possible to have the PXE client and the DHCP server communicate over without DHCP Snooping involved? The easiest way is to configure the port toward the PXE client as a DHCP-Snooping-trusted port. Would that make a difference?

Best regards,
Peter

[marteraam]

Q1:The debugs suggest that either the PXE client or the DHCP server are somewhere in VLANs 50 or 60. Can you be more specific about their VLAN membership?

A1:I tried both ways and even DHCP server PXE server and Client are in the same vlan PSE boot does not work

Q2: Would a normal client in place of the PXE client receive an IP address?

A2: PXE client receive IP just fine

CLIENT IP:172.16.1.155  MASK: 255.255.254.0  DHCP IP: 172.16.0.244  GATEWAY IP: 172.16.0.1 TFTP.

Q3: Also, if the PXE client was moved into the same VLAN as the DHCP server, would it be able to receive its IP address?

A3: Yes.

Q4:Lastly, if possible, would it be possible to have the PXE client and the DHCP server communicate over without DHCP Snooping involved? The easiest way is to configure the port toward the PXE client as a DHCP-Snooping-trusted port. Would that make a difference?

A4: Having all three stations in the same vlan (DHCP PXE and CLIENT) all interfaces set  with "ip dhcp snooping trust" - does not work either, I am able to receive ip address only but PXE boot does not start

[Peter Paluch]

Hello,

Hmmm... I am compelled to ask if the PXE boot ever worked for you, before you even deployed the DHCP Snooping. There is a possibility that the DHCP server you are using does not recognize and add the necessary DHCP options to make the PXE client happy and start booting. What kind of DHCP server are you using? Is that a Cisco-based DHCP server, or is it a server running on Linux or Windows?

Best regards,
Peter