Thanks Lawson. Curious how you decided on two hours. Was that because session times are usually one hour? I like the idea of scopes with 50% utilization. Also very important to watch CPU/load and keep it low.
In this scenario it does mean if your DHCP service fails - every user in your environment will be impacted within one hour right. How hard would it be to buy yourself more time in that regard? What would be the downside of say 24 hour leases? Thanks, Curtis ________________________________________ From: The EDUCAUSE Wireless Issues Constituent Group Listserv <[email protected]> on behalf of Lawson Cassels <[email protected]> Sent: Tuesday, May 8, 2018 8:58 AM To: [email protected] Subject: Re: [WIRELESS-LAN] DHCP Lease Times We have a wireless system that sees roughly 30K unique clients pass through each day. Our address space is set up as a single large /17, as the Aruba controllers are extremely effective at controlling multicast and broadcast... no need to segment the IP space in my opinion. We have the default lease time set to 2 hours, with a maximum of 3 hours. Our address space typically sits at about 50% utilization. We feel that this is a good configuration, as it leaves extra space for special events, unknown emergencies, or address depletion attacks. The load on our Bluecat DHCP servers is well under 25% and they are extremely low end hardware, so it doesn't seem like 2 hours is too short. Lawson Cassels Network Engineer Infrastructure, Operations, and Networking Illinois State University p: 309-438-4318 On 5/8/2018 7:52 AM, Ian Lyons wrote: > If you have Airwave one of the may "dials" is how long is your average > connection. > > Mine is 28 minutes. > > I set my lease time for WiFi for 1 hour. I have a /19, which might be > overkill, but with AD based DNS, I have poor insight into the things that go > bump in the night (for DNS) > > If Cisco, I think there was a Prime option for this data too.... > > -----Original Message----- > From: The EDUCAUSE Wireless Issues Constituent Group Listserv > <[email protected]> On Behalf Of Curtis K. Larsen > Sent: Monday, May 7, 2018 7:17 PM > To: [email protected] > Subject: [WIRELESS-LAN] DHCP Lease Times > > Hello, > > I'm curious to see what process/algorithm others use when determining DHCP > lease times for your Wi-Fi networks. Assuming plenty of IP addresses, what > DHCP lease time is ideal to assign to clients in a WLAN with 90,000 unique > clients/day, where avg. user spends 3hrs connected , but some (maybe 20%) go > several days, Keep in mind that 90% are the same user/device every day. > > What level of DHCP pool utilization do you think is best? Have you found any > industry documentation on this? Thanks in advance. > > -Curtis > > ********** > Participation and subscription information for this EDUCAUSE Constituent > Group discussion list can be found at http://www.educause.edu/discuss. > > ********** > Participation and subscription information for this EDUCAUSE Constituent > Group discussion list can be found at http://www.educause.edu/discuss. ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/discuss. ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/discuss.
