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DHCP - secondary L3 interface


I am in the process of migrating clients from 192.168. IPs over to 172.

The way I have figured I would do this is to migrate the current L3 address on the VLAN (using SVI's) to the new 172 address and then use the existing 192.168. as a secondary L3, in order to not cause disruption and allow clients already with a 192.168 address pointing to the 192.168 gateway to maintain connectivity.

However, one problem would be printers etc with reserved IP's in the 192.168 range - if these were to be rebooted and ask DHCP for an address again they will receive a 172. address, as the MLS will forward to DHCP using the primary L3 address on the SVI.  I have tested this theory and a client regardless of having a reservation in the 192.168 scope receives a new address in the 172 scope.

Is there a way of informing DHCP to issue out reserved IPs from one scope relating to the secondary L3 on the SVI for some devices?

My alternative would be to create a new VLAN (legacy-vlan) for each scope I am migrating and keep this in the 192.168 range and assign switch ports to this legacy vlan for printers, though this increases management burden!

Any ideas would be great,



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