Re: DHCP option 82 support on Cisco Router

There are a couple of options. You can either stop the switch from
inserting option 82 or you can tell the router it is OK to trust it. By
default the router will not trust anything with giaddr = 0 which is what the
switch sets that value to by default : )

option 1: on the router interface: ip dhcp relay information trusted
option 2: on the switch: no ip dhcp snooping information option

HTH!

On Thu, Jul 30, 2009 at 2:05 AM, Ajay mehra <ajaymehra01_at_gmail.com> wrote:

> Hi Guys,
>
> Just wanted to ask a simple question on DHCP snooping and DHCP option 82.
> If
> I enable insertion of DHCP option 82 in switch then what should be the
> right
> configs on router to support option 82.
>
> I get below messages on DHCP server (Cisco Router) when switch is inserting
> option 82.
>
> *Jul 30 06:01:25.275: DHCPD: relay information option exists, but giaddr is
> zero.
> *Jul 30 06:01:29.275: DHCPD: inconsistent relay information.
> *Jul 30 06:01:29.279: DHCPD: relay information option exists, but giaddr is
> zero.
>
> Also what is the significance of giaddr?
>
> Thanks,
> Ajay
>
>
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Joe Astorino - CCIE #24347 R&S
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