DHCP Snooping Problem

[Merijeek]

Hi All -

I've got a five stacks of switches in 5 separate closets feeding back to a central MDF. It's a classic star configuration.

I wanted to go ahead and implement DHCP snooping. To do so, on my MDF (where my DHCP server is located) I ran the following commands:

ip dhcp snooping
ip dhcp snooping vlan 1
ip dhcp snooping vlan 601 605
and then on my DHCP server's interface I did:

ip dhcp snooping trusted

All of my IDFs got the first 3 same commands as the MDF, and then on my trunk port going back to the MDF I put the 'ip dhcp snooping trusted' command.

However, when I did that I started getting people complaining they weren't able to get an IP address.

I saw some crazy things on the dhcp snooping debug that I don't have in front of me at the moment. What I'm really wondering is if I did anything obviously wrong as far as my configuration.

Anyone have any input?

 

[unclerico]

add no ip dhcp snooping information option

I hate all Uppercase... I don't want my groups to seem angry at me all the time! =)
- ColdFlame (vbscript forum)

 

[Belushi]

Yeah, I think unclerico is probably right. That information option is on by default and is many circumstances needs to be turned off. For the rest of the DHCP snooping commands or arguments look here:

http://www.cisco.com/en/US/docs/swi.../12.2_52_se/configuration/guide/swdhcp82.html

Not sure which model you are using but the commands should be similar. All sorts of things you can do plus ad onto it with dynamic arp inspection and ip source guard.

 

[Merijeek]

Okay, sorry it's been so long. I've been busy and actually haven't been back to the site since.

As far as the [/b]no ip dhcp snooping information option[/b], I'm guessing that'll kill the option 82. Why do I want to do that?

-Joe

 

[Belushi]

You would want to kill it in order to work in almost all normal circumstances. Try it and see. For a detailed explanation refer to the link I provided, it'll explain that option and all others.