[ietf78-tech] Impact of long leases on IPv4 DHCP address ranges for wireless

[Bill Jensen]

At the risk of missing the point here, I would suggest not deviating 
from our "normal" lease times for a heavy AP environment.

If the hope was to assist captivator behavior, I will claim its 
unnecessary.  Running long lease times is fine but running short leases 
is also fine.  (We have certain AP subnets at UW-Madison where leases 
are cranked down to around 15 minutes to shed transient hosts that 
obtain addresses - such as when hundreds of students are moving about 
during class change.)  If there is concern about ip*tables growing 
larger, we have two things working in our favor.  1) There are automatic 
and manual methods to flush rules associated with inactive flows or all 
rules, 2) historically we have never reached a client count that poses a 
serious performance risk short of a possible scenario where every client 
appears on a single vlan.

Thoughts?  :-)

-wej

On 7/8/10 6:06 PM, Chris Elliott wrote:
> On Jul 8, 2010, at 6:54 PM, Jim Martin<jim at daedelus.com>  wrote:
>
>>     Running out? It's a /16 :-)
>>
>>     We usually tend to live in the lower /17, so we should be fine.
>
> Of course. But I'm talking about our VLAN configuration.
>>
>
>>     - Jim
>>
>> On Jul 8, 2010, at 6:50 PM, Chris Elliott wrote:
>>
>>> All,
>>>
>>> Are we going to need to expand our v4 DHCP address ranges and probably also our subnet sizes because we are planning on much longer DHCP leases to support authentication?
>>>
>>> I haven't done the math and I don't know if we have any data on how close we have come to running out, with the exception of Anaheim when Swisscom mistakenly assigned a DHCP range for a /24 subnet for the wireless VLAN.
>>>
>>> Chris.
>>>
>>>
>>> --
>>> Chris Elliott
>>>
>>> _______________________________________________
>>> ietf78-tech mailing list
>>> ietf78-tech at daedelus.com
>>> http://www.daedelus.com/mailman/listinfo/ietf78-tech
>>
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-- 
Bill Jensen, Network Engineer
UW-Madison DoIT Network Services
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