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New Member

IOS DHCP Server reservation (Windows and linux)

Hi There,

I have a dual boot laptop that I want to get the same IP address whether it boots to Windows or linux.

I have it working in Windows with the following

!

ip dhcp pool Laptop

host 192.168.10.80 255.255.255.0

client-identifier 0100.0fb0.463c.1b

!

However because windows seems to need "01" before the ACTUAL MAC address, and linux does not, then I do not get the same IP.

Is this possible?

Thanks,

Peter.

5 REPLIES
New Member

Re: IOS DHCP Server reservation (Windows and linux)

From my point of view it depends only on the Ethernet-Type used by the NIC, not the OS.

On the other hand, DHCP is a process controlled by the OS and the OS may have to decide which Ethernet-Type is used for encapsulation.

> Specifies the unique identifier for DHCP clients. This command is used for DHCP requests.

> DHCP clients require client identifiers. The unique identification of the client is specified in dotted hexadecimal notation, for example, 01b7.0813.8811.66, where 01 represents the Ethernet media type.

Source:

http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fipr_c/ipcprt1/1cfdhcp.htm#wp1001108

Hope that helps,

Rolf

New Member

Re: IOS DHCP Server reservation (Windows and linux)

Found this value-list in RFC 1700:

Number Hardware Type (hrd)

------ -----------------------------

1 Ethernet (10Mb)

2 Experimental Ethernet (3Mb)

3 Amateur Radio AX.25

4 Proteon ProNET Token Ring

5 Chaos

6 IEEE 802 Networks

7 ARCNET

8 Hyperchannel

9 Lanstar

Maybe a debug-command shows different frame-types?

Hard to believe that the MAC-Address is different if you boot Linux.

New Member

Re: IOS DHCP Server reservation (Windows and linux)

Thanks guys, I will mess around with the Linux settings to see if I can get this working.

New Member

Re: IOS DHCP Server reservation (Windows and linux)

I played a little bit with Wireshark and watched the DHCP-Discovers from a Windows XP PC and those from a SuSe-Linux PC.

Both OS used Ethernet II frames!

Because of this result I'd recommend debugging DHCP on the Cisco-Switch.

New Member

Re: IOS DHCP Server reservation (Windows and linux)

use "hardware-address" (don't put the 01 in front just the mac addr xxxx.xxxx.xxxx) for your unix box and "client-identifier" for your windows box, as far as i know you can't have both on the same "ip dhcp pool" and if you create a different pool for the same host ip so you can put "hardware-address" command in you will get an error "% A binding already exists..." because you're assigning the same ip to different pools

hope this makes sense, mike

client-identifier

http://www.cisco.com/en/US/products/sw/iosswrel/ps1831/products_command_reference_chapter09186a00800ca694.html#wp1017558

hardware-address

http://www.cisco.com/en/US/products/sw/iosswrel/ps1831/products_command_reference_chapter09186a00800ca694.html#wp1017792

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