In particular they dont need IP helper statements or layer-3 interfaces for all of their VLANS, right?Ĭorrect. Snooping turned on (both globally and on the VLANS) and their uplinks to Given that the access switches are only switching, they only need DHCP

I believe that if all I do is turn DHCP snooping on globally and on the right VLANS the DHCP relaying between the core and the DHCP server will continue working just like it is today, is that correct?Īre there really any gotchas to this or in my case do I really just need to turn it on globally and per vlan, trust the uplinks on the acccess switches and the DHCP server interface on the core and call it a day? As near as I can tell its optional for the server to use the Option-82 information.

The most confusing part is all the Option-82 stuff.Of cource the cores do trust the actual interface the DHCP server is plugged in on I got that on the access layer switches the uplinks to the core are trusted, but I am not 100% on whether the same interfaces are trusted on the cores.While I understand that DHCP snooping will only be marginally effective if it is not turned on on the core, there is no reason I cannot deploy it first at the access layer without touching the core configurations to avoid large amounts of change-control paperwork, right? Then when the core is upgraded and DHCP snooping properly enabled it will work.Given that the access switches are only switching, they only need DHCP snooping turned on (both globally and on the VLANS) and their uplinks to the core set as trusted, right? In particular they dont need IP helper statements or layer-3 interfaces for all of their VLANS, right?.

I have also read all the info I could find on DHCP snooping but am still a little fuzzy about if it changes how the DHCP server handles requests. The DHCP server that supports all the VLANS is a Windows 2008 server directly connected to the core. The new cores are 6509 Sup 720's configured as a VSS cluster, handle all the routing for VLANS and have the IP helper statements. The new access switches are 4510R+E/Sup7 running latest IOS XE base license and only doing switching. During the tech refresh the access switches will be upgraded first then the core. As part of a tech refresh project at a large campus and due to several issues caused by (l)users plugging in home routers to the network and causing DHCP issues I am looking to enable DHCP snooping.

Dhcp option 82 windows server 2008