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fofanah78

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Changing DHCP scope with a different subnet mask

I’m planning to extend my DHCP scope and remove some of the users from my server Vlan5 to the user Vlan6-7.

Current User Vlan6 192.168.6.0/24 - Vlan5 192.168.7.0/24
Current Server Vlan5 192.168.5.0/24
Windows Server 2012 with all my scope options.
Using a Cisco 3750 Switches

User Vlan6-7 to a /23 address so I will have enough addresses for the users that are on my vlan5.
What will be the best option to do this without an IP address conflicts?
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masnrock
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You need to be sure that you are selecting subnets that do not conflict. For example, if you use /23 for vlan6 without changing anything, vlan7 will conflict.

So you may want to either have a totally new address range or be ready to change vlan7 as well as vlan6.
All they all DHCP clients on the user VLAN?

How may endpoints and switches are impacted?

If it is not so many you can change the DHCP scope, and shutdown/no shutdown the interfaces or reload the switch if possible.  The other option is shorten the DHCP renew time to something small, make the switch after the currect time has elapsed, and the clients will renew with the new IP.

Or lastly, these are users, I assume, make the change overnight and ask them to reboot.
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Mal Osborne
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