Force10 MXL 10/40 dhcp snooping issue

Are you wanting to relay DHCP requests from one VLAN to another? If so, I believe you need to configure the ip helper address.

# ip helper-address {DHCP server IP Address}

http://dell.to/2DRBaiu

This configuration from switch with server connected to it and at this moment we're trying to implement snooping in single vlan. Port with server was configured as trust and after that this message appeared in the log and non of the clients are getting ip from this server.

I believe there should be option to allow empty giaddr field like it exist on Cisco gears

I see, thanks for the extra information. Taking out the DHCP relay portion should take care of option 82 being used.

# No ip dhcp relay information-option trust-downstream

Just to confirm, the trust mode command is on the server facing interface?

Can you please post up the output from the following command?

# show ip dhcp snooping

Here is current config, dhcp snooping disabled globally since chassis is in production at this moment

ow-ch05-switch#sh ip dhcp snooping 

IP DHCP Snooping                           : Disabled.
IP DHCP Snooping Mac Verification          : Disabled.
IP DHCP Relay Information-option           : Disabled.
IP DHCP Relay Trust Downstream             : Enabled.

Database write-delay (In minutes)          : 0

DHCP packets information
Relay Information-option packets           : 0
Relay Trust downstream packets             : 0
Snooping packets                           : 0

Packets received on snooping disabled L3 Ports   : 0
Snooping packets processed on L2 vlans     : 0

DHCP Binding File Details
Invalid File                               : 0
Invalid Binding Entry                      : 0
Binding Entry lease expired                : 0
 
List of Trust Ports                        :
Te 0/4
Te 0/9  
Te 0/44
Te 1/4
Te 1/9
Te 1/44
 
List of DHCP Snooping Enabled Vlans        :

Ports number 44 are uplinks, 9 and 4 are dhcp servers half-size blades.

I tried both options with and without "information-option trust-downstream", but nothing changed

I was running through the commands you have implemented and received a warning when issuing the snooping vlan command.

Dell(conf)#ip dhcp snooping vlan 1-4094
% Warning: Snooping cannot be enabled on default vlan.

Did you run into this same message? Or has the default VLAN been changed?

For some reason I was thinking this was all on VLAN 1. In the show output, were there any VLANs listed after

List of DHCP Snooping Enabled Vlans      

 If not, can you please try just enabling the snooping on VLAN 30?

Thanks, I just wanted to be sure the VLANs were listed.  I could not find a command that would allow for zero giaddr. I would like to help look into this further and have sent you a private message requesting some additional logs from the switch. I look forward to hearing from you.

Found post similar to mine. Just adding here for history

https://www.dell.com/community/Networking/DHCP-snooping-between-multiple-switches-and-how-to-make/m-p/5173077

For anyone else experiencing similar behavior. What we found was that the switch may need to have DHCP relay enabled, even if the interface is layer 2. The switch will also need to have each VLAN created on it, and snooping enabled on that VLAN.