Wireless Access

We've been having issues with APs not renewing their DHCP lease since we moved to 6.3.1.3.  Once a lease hits 50% of the lease duration, how often does it try to get a new IP address (seconds, minutes, hours)?  I have lots of traces of an AP at 56% of the lease and one at 99% of the lease but neither ever do a DHCP request to get a new IP address.  I'm re-opening our TAC case but was wondering if the time between requests is very large.

Which AP platform?

60, 61, 65, 105 and 125.  We installed our first 225s a couple of weeks ago so there isn't enough time to know for sure with them.

The issue started with 6.3.1.3.  It happens on M3, 7210 and 7220 controllers.

This is more of a workaround than a solution but have you considered assigning static IP's?

It helps if you ever want to add them into a monitoring system like What Up Gold.

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@RHertzing wrote:

This is more of a workaround than a solution but have you considered assigning static IP's?

It helps if you ever want to add them into a monitoring system like What Up Gold.

 

 

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Rhertzing,

Managing static ip addresses for hundreds of access points produces management challenges of their own.  Aruba access points are designed to NOT have static ip addresses to avoid that.  In addition, since Campus APs do not respond to SNMP gets, all What's up gold can give you in exchange for managing static ip addresses is and up/down.  I am not saying that it is impossible to have APs with static ip addresses, but it increases management overhead to do so.  The controller keeps track of what access point has what ip address even if it is down.  In addition, it can send SNMP traps when access points come up or down.  Lastly, if you wanted to re-ip your network, having static ip addresses on your access points would make that much more difficult, especially in large environments.  With APs that have DHCP, changing the IP address scheme of your network would be straightforward.

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@pdavis wrote:

60, 61, 65, 105 and 125.  We installed our first 225s a couple of weeks ago so there isn't enough time to know for sure with them.

 

The issue started with 6.3.1.3.  It happens on M3, 7210 and 7220 controllers.

 

 

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Pdavis,

What is your current DHCP lease time?  According to the DHCP standard, the client *should* wait 1/2 of the DHCP time before renewing but I am not sure that it is mandatory.  Do you have any access points that retain beyond the lease?

Our current standard lease is 100 days.  I have gone to 2 sites today to get traces of APs with leases over 50 days old.  They have not updated their lease in the DHCP server and traces indicate they are not sending out requests.

Since some of the APs have a lease of 56 days and other have 99 days, I would think I should have seen at least 1 DHCP request in the ~8 captures.  Two of the captures are on the uplink of a switch stack of 6-10 APs which should be asking for a new DHCP lease.

With over 3300 APs, static IPs are not an option for management reasons (and others listed by CJoseph).

pdavis,

We fully respect your need or requirement to have a 100 day lease.  It would be much harder to replicate the possible issue (because it would take 100 days) that it does not renew the lease in the required time.  Is there any way as a test to reduce your lease on a smaller subnet to something like a day and reboot all of the APs as a test?

So did you want to renew on the same subnet or on another subnet?

We are trying to renew on the same subnet.

I'm going to find a place to set up some APs for a shorter lease.  We have a site which is undergoing some rennovations this summer which means there shouldn't be many (or any) people in there.