DHCP with Option 82.

[carmenanderson]

Per my customer they want to do DHCP with Option 82.

I am having trouble finding the initial hex information for the cisco 2901/2911 routers I am using. I also need it the hex information for 3900 and 4451 routers; I have not been able to find any CISCO documentation that specifies what the hex code is.

The Italic is the portion I am talking about, I can decipher the bold portion.

The other vendor I have gave me their hex code. Will it change per the modules that you use or just the model number of the router or switch. What about NIM/SM modules, that are physical cards but virtually different devices but on the module?

Relay-information hex 01080206006401010F*

• Vlan and port is included in the hex string above:
  64 = 100, the VLAN

01= 1, switch number (always 1 as we don’t stack switches)

01=1, module number in switch

0F=10, port number in module

[carmenanderson]

Disconnect the device clear DHCP.

Option 82 you need to run

debug ip dhcp server class
debug ip dhcp server event
debug ip dhcp server packet detail
debug ip dhcp snooping packet

Reconnect the device,

On your cisco device run

sh run | in DHCP

You will then see a hex 520e020c020a0000c0a8670e0106001e simalar to this.

remove the 520e and that will be your relay information hex.