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

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

For an introduction to the new site, click here. And see here for current known issues.

New Member

ip dhcp snooping

can anyone tell me what ip dhcp snooping

means ?

Super Bronze

Re: ip dhcp snooping

It means a few things - basically

1) In configuration terms, you enable it globally on the switch, then on each VLAN you want, then set each port on the switch to either 'untrusted' or 'trusted' - with trusted being a port where you would expect DHCP offers to be rec'd (i.e. server ports or uplinks), and untrusted being a port where you would expect DHCP Discover packets (i.e. end user ports).

2) It prevents DHCP offers coming from 'edge' or 'untrusted' ports - for example stopping someone plugging in an AP or web router that gives out DHCP and disrupts service on your net work.

3) It also does several other checks - e.g. checks that DHCP packets on 'untrusted' ports are being sent for only real MAC addresses on the port (so one PC can't use up all your scope addresses, or release someone else's IP address lease).



Please rate helpful posts...

Aaron Please remember to rate helpful posts to identify useful responses, and mark 'Answered' if appropriate!
New Member

Re: ip dhcp snooping

so is this a global or per port command ?

New Member

Re: ip dhcp snooping

This is helpful.

Do you have any experience with configuring trunks for this?

CreatePlease to create content