DHCP - Routed - Fails for 'Some'

[Neil Kirkland]

I have a routed DHCP from 4 VLAN's and it works fine except in certain cases - those cases are where a remote PLC tries to call back as a PXEClient.

No DHCP discover packets are forwarded by the 'routing' process if the packet contains option 60 = "PXEClient : Arch ......" - leastways that's how it looks.

The routed trunks both have "ip dhcp relay information option enable"  set, yes the VLAN's do have 'ip helper-address =' settings one for both  the primary DHCP box and another for the PXE server. I've played with portfast and vaious other options, nothing has helped.

If I connect the PXE Server (OK so its a laptop) into the same VLAN as the PLC the PXE boot process works fine so I know that this is related to the routing / relay agent. I have verified on the server switch and VLAN that the issued 'PXE' discover message is never received, I have verified of course that it is sent.

In any case normal DHCP and DNS operations function correctly each VLAN device gets an appropriate IP address from the appropriate scope and a suitable DNS entry - but anything that tries with option 60 set to "PXEClient : *******" fails - or is it option 252 - Private/Proxy autodiscovery ?

Switches are 3560's using EIGRP routing via fibre trunks.

This has to be something simple that I've missed, I've read an encyclopedia worth of posts on here re PXE issues nothing has so far solved. Is there any way to log what the routed interface is doing with DHCP /  Bootp traffic?

(DHCP and DNS are provided by Microsoft Server 2008 R2)

[paul driver]

Hello

have you reviewed this link?

http://msdn.microsoft.com/en-us/library/dd128762(v=winembedded.51).aspx

res
paul

Sent from Cisco Technical Support Android App

[Neil Kirkland]

Have now - it isn't that - the discover packets aren't even reaching the switch / VLan where the PXE Server resides.

The PLC device when loaded CAN get a DHCP address from the MS DHCP Server.