How to allocate IP address via switch port ?

[henrybb]

My network topo is like this:

SWITCH 1----SWITCH 2--PC

DHCP services is running on SWITCH1. And I need that DHCP allocate IP address for PC which it inspect both the giaddr and switch port information.

But I can't find information about option 82 format of cisco switch.

So how to config "relay-information hex " if I need allocate IP via switch port information. And how to enable option 82 insertion on switch 2 ?

thanks!

[Bobby Thekkekandam]

Hi Henry,

Are you running IOS DHCP server on the switch? If so, option 82 is not supported. If not, and you want to enable DHCP snooping, support depends on the switch platform in question. What type of switches are you dealing with?

HTH,

Bobby

*Please rate helpful posts.

[henrybb]

Hi Bobby,

I running IOS DHCP server on the switch 1. And I need that switch 2 can insert port information to DHCP packet as option 82.

What you mean when you said " If so, option 82 is not supported" ? Do you mean switch doesn't support option 82 if it is running IOS DHCP server. And switch DO support option 82 if it is NOT running IOS DHCP server.

Switch 1 is 4510 with SUP V, switch 2 is 3750 or 2950.

thanks!

[Bobby Thekkekandam]

Hi Henry,

The switch supports option 82 insertion, however IOS DHCP server does not support this, so the DHCP server process will not know how to properly interpret the DHCP packets with the option 82 insertion. Does that make more sense?

-Bobby

[henrybb]

Hi Bobby,

You mean CISCO IOS DHCP server does not support option 82. But I see that IOS 12.4 support it on http://www.cisco.com/univercd/cc/td/doc/product/software/ios124/124cg/hiad_c/ch10/hipdhcps.htm#wp1097363. Can you give more information?

Anyway, if I use other DHCP server which support option 82, how to enable option 82 insertion on cisco catalyst switch and how to code switch port information ?

thanks!