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DHCP 2012 R2 adding digits to MAC address out of nowhere?

Question

Tuesday, July 8, 2014 5:35 PM

We are having an issue with our Windows DHCP 2012 R2 cluster. I'm not sure if this is because it's a cluster or what, but I've never seen this problem before. We are going around and changing all of our printers in the enterprise from static IP's to DHCP MAC address reservations.

From the 

As you can see from the screenshots the MAC addresses for a few of the printers seem to have a whole bunch of extra zero's at the end. These were NOT there when we added the MAC addresses reservation. They seem to be cropping up randomly a few days after we add the reservations. Has anyone ever run into this before?

All replies (4)

Wednesday, July 9, 2014 10:08 AM ✅Answered

http://technet.microsoft.com/en-us/library/cc977614.aspx

The unique id can be, but does not have to be the client MAC.

Some HP printers send an mismatched DHCP Client Identifier due to an issue in the printer's DHCP client software. Instead of sending the DHCP Client Identifier by concatenating the hardware type (normally '01') and the hardware address, they generate the DHCP Client Identifier by concatenating '00' and the hardware address. If the printer's DHCP client software can be reconfigured to stop sending any DHCP Client Identifier, you may choose to do that. Or reconfigure the printer so it doesn't rely on its DHCP client software; have it learn its IP information via BootP or manual configuration. Or get the vendor to fix the DHCP client firmware (through a firmware update).

MCP/MCSA/MCTS/MCITP


Thursday, July 10, 2014 7:38 AM ✅Answered

Hi,

The DHCP Options and BOOTP Vendor Extensions provide by DHCP clients, in general is the client MAC, but it does not to be, you can configure your printer use the MAC as the identifier.

More information:

Client Unique Identifier

http://technet.microsoft.com/en-us/library/cc977614.aspx

RFC2132

http://www.ietf.org/rfc/rfc2132.txt

Hope this helps.

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Thursday, July 10, 2014 1:58 AM

Manual is not an option.

According to this article a change of the adapter on the printer from auto negotiate to 100TX-Full fixed the issue for a number of them. Would this have any affect?

http://h40434.www3.hp.com/t5/Printing-Issues-Troubleshooting/HP-LaserJet-200-MFP-networking-issues-via-DHCP/td-p/2788897/page/2

Would BootP really be a long term solution to this problem? Does BootP not send back a UniqueID?


Tuesday, July 15, 2014 2:06 AM

Hi,

Just want to confirm the current situations.

Please feel free to let us know if you need further assistance.

Regards.

We are trying to better understand customer views on social support experience, so your participation in this interview project would be greatly appreciated if you have time.
Thanks for helping make community forums a great place.