How to expedite leasing an IP address (Secondary and Primary swapping)

[ethanpark0726]

I have deployed /25 network for APs but it is already exhausted so I had to add /24 network and I promoted /24 network to the primary address.

So, the current configuration is:

interface Vlan100

 description AP

 ip address 192.168.227.129 255.255.255.128 secondary

 ip address 192.168.241.1 255.255.255.0

 ip helper-address x.x.x.x

When the lease time of the /25 network is over, a device will get the newly deployed /24 network's IP address. Is there any way to expedite this process?

[balaji.bandi]

The best approach is, take the maintenance window and change to new IP,

[Richard Burts]

If I understand the original post correctly the question is about hosts which currently have IP addresses from the /25 network and if there is a way to get them to acquire a new address before the expiration of the current lease. If I understand the suggestion from @balaji.bandi correctly he is suggesting that in a maintenance window that you remove the /25 and replace it with the /24 (no secondary IP). The result would be that all clients still using the old /25 address would stop working. Eventually users would get frustrated that their device was not working and would reboot, then would acquire a new address and would work. So it would work (sort of) but would be a very user unfriendly solution.

Realistically I do not see any effective and user friendly solution other than waiting for current leases to expire (the secondary address solution). How long are the leases of the /25 devices?

[ethanpark0726 · Accepted solution]

As you said, there is no effective way for this. Even if the lease expires, the device continues to renew the /25 IP address instead of the /24, which is the primary network.

[balaji.bandi]

Glad all working well and you able to resolve the issue, apprciated your input.

[paul driver]

Hello

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@ethanpark0726 wrote:

the device continues to renew the /25 IP address instead of the /24, which is the primary network.

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This is not the case if the primary ip address is changed, the dhcp scope related to the /24 should begin to be serviced.

[paul driver · Accepted solution]

Hello
when you change the primary addressing on an interface its that primary ip address that will be used for the gateway ip address in the dhcp packet - Now if the dhcp server scope is exhausted for the primary ip address or for some reason it isn’t able to respond on that primary ip then dhcp allocation is lost because by default the secondary ip addressing isn’t utilised by dhcp, However this can be changed by using a global feature called ip dhcp smart-relay which will relate the secondary addressing assigned to that interface as the giaddr in the dhcp packet sent to the dhcp server.

[Georg Pauwen · Accepted solution]

Hello,

what are you using as DHCP server (e.g. Windows Server 2012 R2) ?