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Author Topic: Max value for DHCP lease time?  (Read 25610 times)

bjrichus

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Max value for DHCP lease time?
« on: September 23, 2008, 07:17:36 PM »

Firmware rev 1.05.

I have my DHCP lease time set to 180 minutes and the leases are being released/renewed once every 90 minutes. This is as expected - see an earlier thread about this.

What value do others who use DHCP have this value set to?

DLINK Tech support - Is there a maximum value for the DHCP lease time value? 

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bjrichus

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  • Posts: 119
Re: Max value for DHCP lease time?
« Reply #1 on: September 24, 2008, 01:43:25 PM »

I got my DHCP time up to 999 minutes and sure enough at about 8 and a third hours (half that value), they all renew.

Wonder how it'll go with an extra '9' in there - should be about 3.4-ish days to each renewal... yes?

9999/60 = 166.65

/2 = 83.325

/24 = 3.47

Is this correct?



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cloon

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Re: Max value for DHCP lease time?
« Reply #2 on: September 24, 2008, 01:54:17 PM »

I've currently set this option at 3600 ( without thinking about it )

Your calculation are right but I really don`t know if its higher than the limit allowed by this unit.

Can I ask why the renewing bother you ?  If you use DHCP reservation you will always get the same ip and the only side effect that I see right now is the log that get `full faster` and you get an email more often...(if you've set up the unit to send mail )

Don't try "0" it's not "never expire"  ;D

  • Setup DHCP reserved IP addresses.
« Last Edit: December 16, 2014, 11:46:20 AM by FurryNutz »
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bjrichus

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Re: Max value for DHCP lease time?
« Reply #3 on: September 24, 2008, 06:57:53 PM »

Can I ask why the renewing bother you ? 

The fact of a renewal doesn't worry me, it's that every time it does renew, the connection is lost as the client reconnects. This is a problem for one PC that is always on and is hooked into weather reporting equipment and onto the Internet, so ideally needs to be up 24x7x365 (an impossible dream, I know). The fix is to use an assigned IP address, rather than DHCP (even if the same address always get re-assigned) and that will be the way to fix that one device.

But we also have several laptops that I use the Cisco VPN client on and they may be online for ages (certainly a full working day and often well into the evening) and as I am running SSH protocols to command line sessions on large Unix servers - think Sun Microsystems gear, typically with 32xCPU and 256Gb RAM - for system admin tasks...

I cannot use those devices over my wireless link with confidence if the session 'dies' due to a 'pointless' lease renewal.

Can't use static IP assignments on these devices as they also 'roam' to other wireless locations, so would need to go from DHCP and back to static all the time... a real pain!!!

Don't try "0" it's not "never expire"  ;D

Ha! Thanks for the tip.

Anyway, that's why I asked.... I really would like to set the the DHCP lease time to the upper limit, to reduce my "problem".

 :D
« Last Edit: September 24, 2008, 07:00:02 PM by bjrichus »
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