Current situation: we have a C3850 switch serving DHCP lease to desktop clients without communicating with any upstream DHCP server
Objective: We would like the C3850 switch continue to serve DHCP lease on VLAN60 while Microsoft DHCP server could see all the DHCP lease from C3850 on VLAN60
Remark: I know "ip helper-address" feature exists on the Cisco switch, but it will forward DHCP client request to the Microsoft DHCP server instead of having a local DHCP server in the C3850 switch, that's not what we want to do. C3850 could communicate with Microsoft DHCP server on layer 3 routing without problem.
Question: how exactly could I implement DHCP relay on C3850 with Microsoft DHCP server without impacting existing DHCP lease on C3850 right now?