DHCP snooping across 2 switches

mikedelafield · ‎06-26-2008

i cannot get DHCP snooping to work across 2 separate switches.

DHCP snooping is enabled on each VLAN and the DHCP server is located on switch 1 with the interface is trusted.

from switch 2 DHCP works okay when DHCP snooping is not enabled on switch 2.

once DHCP snooping is enabled on switch 2 it no longer works. i've tried trusting the trunk link to switch 1 but it still does not work

HELP!!

andrew.butterworth · ‎06-26-2008

You need to apply trust on each end of the trunk as DHCP packets will travel both ways (Client requests and Server responses).

interface GigabitEthernet0/1

ip dhcp snooping trust

Andy

mikedelafield · ‎06-26-2008

is the correct command at either end of the trunk; ip dhcp snooping trust?

as i have also read about the following command;

ip dhcp relay information trusted

francisco_1 · ‎06-26-2008

use " ip dhcp snooping trust" on your uplink (trunks) ports as trusted

francisco_1 · ‎06-26-2008

to setup dhcp snooping,

1, enable dhcp snooping globally " switch(config)#ip dhcp snooping"

2, enable dhcp option 82 to forward dhcp request packet to contain information on the switch port where it originated(optional) "switch(config)#ip dhcp snooping information option"

3, configure dhcp server interfaces or uplink ports as trusted " switch(config-if)#ip dhcp snooping trust"

4, enable dhcp snooping on specific vlans " switch(config)#ip dhcp snooping vlan (vlan number)

5, vertify the configuration " show ip dhcp snooping.

pls rate if this helps

wizassonic · ‎06-27-2008

In the global config you need:

(config)#ip dhcp snooping

AND

(config)#ip dhcp snooping vlan 1

On my switches if I don't issue both commands it doesn't work.