Nexus 7000 DHCP Relay

Peter Welcher
Architect, Operations Technical Advisor

One of my consulting customers pointed something out to me that I hadn’t known. IP helper (now DHCP relay) works differently on the Nexus 7000 than on the 6500. The N7K imposes a VACL to filter local DHCP broadcast traffic, under the assumption that you’d be using DHCP relay when there is no local DHCP server. So if you are planning on using a local DHCP server with the DHCP relay (former helper) address providing fallback to a remote DHCP server, you need to put in a DHCP relay line for the local server as well as the remote one.

For full details and a configuration example, see

Here is my version of the configuration example provided:

interface vlan 10
  ip address
  ip dhcp relay  ! remote DHCP server
  ip dhcp relay  ! localDHCP  server

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