Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

DHCP Snooping on a trunk interface

Hello

I have the following set up on my network.

dhcp.JPG

My problem is that i cannot get a DHCP address on the client.

I have the following config for both:

Global

#################################

ip dhcp snooping

ip dhcp snooping vlan 10 , 20 , 30

##################################

Interface trunk

#################################

switchport mode trunk

switchport trunk allow vlan 10,20,30

switchport trunk encapsulation dot1q

ip dhcp snooping trurst *only on the Client's switch

#################################

Thank you !

3 REPLIES

Re: DHCP Snooping on a trunk interface

My problem is that i cannot get a DHCP address on the client.

I have the following config for both:

Global

#################################

ip dhcp snooping

ip dhcp snooping vlan 10 , 20 , 30

##################################

Interface trunk

#################################

switchport mode trunk

switchport trunk allow vlan 10,20,30

switchport trunk encapsulation dot1q

ip dhcp snooping trurst *only on the Client's switch

#################################

Thank you !

Hi,

To configure DHCP snooping just follow these steps

The first step to configure DHCP Snooping is to turn on DHCP snooping in all Cisco Switches using the “ip dhcp snooping” command.

All Cisco Switches (config)#ip dhcp snooping

Second step is to configure the trusted interfaces,

Switch(config)#interface range  gigabitEthernet 3/21 - 23
Switch (config-if)#ip dhcp snooping trust

Finally configure VLANS for DHCP snooping DHCP snooping will used on all the VLANs

Hope to Help !!

Ganesh.H

New Member

Re: DHCP Snooping on a trunk interface

I've got working but only when i add the comand ip dhcp snooping trust to both trunking interfaces.... why is that ? should not it only need the trust command on the client's switch trunk ? Why does it need to be on both trunks? The servers switch only will forwared the DHCP packets to the client why does it need to be trusted ?

Thank you !

New Member

DHCP Snooping on a trunk interface

this explain quite well, mostly due to option82 enabled by default.

http://packetpushers.net/ccnp-studies-configuring-dhcp-snooping/

8682
Views
0
Helpful
3
Replies