From: kevin gannon (kevin@gannons.net)
Date: Sun Sep 25 2005 - 09:21:01 GMT-3
If I have a topology where a DHCP server and DHCP clients are on the same
VLAN and I use DHCP snooping I get the following error on the IOS DHCP
server:
R3#
*Mar 7 22:02:58.894: DHCPD: inconsistent relay information.
*Mar 7 22:02:58.894: DHCPD: relay information option exists, but
giaddr is zero.
*Mar 7 22:03:01.894: DHCPD: inconsistent relay information.
The reason I think is that Option-82 is being set by the 3550 when it
forwards the DHCP to the server but the request looks like:
6w1d: DHCP_SNOOPING: process new DHCP packet, message type:
DHCPDISCOVER, input interface: Fa0/5, MAC da: ffff.ffff.ffff, MAC sa:
0009.b7d1.6fe0, IP da: 255.255.255.255, IP sa: 0.0.0.0, DHCP ciaddr:
0.0.0.0, DHCP yiaddr: 0.0.0.0, DHCP siaddr: 0.0.0.0, DHCP giaddr:
0.0.0.0, DHCP chaddr: 0009.b7d1.6fe0
No Giadrr the the VLAN that the DHCP discover is sent into has an IP address in
the VLAN on the switch howevre it never uses this as the source adress for GI.
The only way I found to fix this was to use a help adress under the VLAN. This
seems a little odd as you dont usually help traffic within the same VLAN.
My questions:
1. Is this simply an IOS with the IOS DHCP server ?
2. Is there some way to disable the sending on the option 82 packet
when doing snooping ?
Thanks & Regards
Kevin
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