DHCP server not reusing expired leases

[Jernej Vodopivec]

Hi,

I'm using DHCP server on SF300 switches for assigning IPs to guest clients.

DHCP lease expiration time is set to 1h, start address is 192.168.1.11 and end address is 192.168.1.20.

SF300 switch assigns all 10 IP addresses to different clients until pool gets exhausted. After 1 hour all DHCP leases become expired and I can verify this on address binding page.

Problem is new clients are connected after let's say 2 hours and they can't get IP address from SF300 switch because pool is exhausted and switch don't delete/reuse expired DHCP leases.

Is there any way to force switch to reuse or delete obsolete DHCP leases so new clients would be able to get valid IP address?

[Gary Paciello]

Hello there,

You can use the command (in privileged EXEC) clear ip dhcp binding X.X.X.X or just an * (asterisk) but if you use just the asterisk instead of an specific ip addresses, ALL bindings will be cleared, including active ones.

Hope this helps.

[Jernej Vodopivec]

Hi,

thank you for information. I know expired bindings can be deleted from privileged cli or web interface but I want this to be done automatically.

Any idea?

[Jernej Vodopivec]

The issue is resolved with the latest firmware 1.4.0.88.

[ifradsham]

Is this something you had to configure to work in the new firmware or did you just upgrade to the the 1.4.0.88 firmware and dhcp server starting to automatically reuse expired lease addresses?

[Jernej Vodopivec]

Hi,

I've just upgraded to newest firmware and that was it. Did you experience some other issue?

[ifradsham]

No, I haven't been able to upgrade yet, but I was wondering if there were any specific configuration commands to be applied to the dhcp settings after upgrading to make this work or if it was simply the change in firmware that fixed your problem.

Thanks.

[Jernej Vodopivec]

I had to upgrade boot code before the upgrade of firmware. That was the only catch.

After the upgrade the dhcp server started reusing IP addresses of expired DHCP leases.