IP churn, maybe due to shared-network?

[Jim Glassford]

Hi Norman,

May not be related at all but for what it is worth if Cisco controller 
environment and might be related to other light weight controller 
deployments.

<http://www.cisco.com/en/US/products/ps10315/products_tech_note09186a0080bb4900.shtml>

"In the previous implementation, using the round robin algorithm was 
causing clients to obtain new IP addresses on every re-association, thus 
depleting IP addresses fast from the available DHCP pools. The new 
algorithm is based on the Client’s MAC address and operates in this way:..."

best,
jim

On 10/31/2012 9:18 AM, Norman Elton wrote:
> We've noticed that there is a higher-than-expected amount of IP churn
> for our wireless clients. That is, clients are connecting to the same
> network, but being assigned different IP addresses in the pool.
>
> I don't believe it's due to over-subscription. In the past few months,
> we've had a total of 13K unique devices with 12K available IP addresses.
> This might affect a transient device or two, but our long-term customers
> should retain the same IP.
>
> We do; however, have shared-networks setup. Each shared-network consists
> of a /21 (2000 clients) and a /23 (500 clients).
>
> So here's the question ... when there are two subnets defined inside a
> shared-network, does dhcpd always prefer using A, even if the client has
> an existing lease from B? That is, does it only use B if A is completely
> filled with active clients? This would certainly explain the behavior
> we're observing.
>
> Thanks!
>
> Norman Elton
>
>
>
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