Inactivity timeout feature

Summary

This article explains the need for inactivity timeout for clients.

Question

What is the need for inactivity timeout?

Customer Environment

ZoneDirector or SZ managed wireless network.

Root Cause

Client entry deletion on the controller due to inactivity.

Resolution

Once a client makes a connection, AP will keep monitoring for its traffic. If there is no traffic at all for a certain period of time, the AP will remove that particular client's entry. This period is called the Inactivity Timeout.

We could set a value between 1-10 minutes on Sone director with the default being 5 minutes. On the SZ platform, the inactivity time out value could be set between 60-1000 seconds with 120 seconds being the default.

When this value gets triggered, AP will also send a disassociate packet to the client and log a message under events.

This type of purging of inactive client entries is essential especially if the environment is highly transient in terms of client foot traffic. This is true for shopping malls and city-wide WiFi deployments. This purging will avoid controller resource consumption in maintaining client entries that are no longer active on the network. This will also help to avoid controller reaching system limits in terms of the number of clients that can connect.

There may be certain deployments where the default inactivity timeout can cause unnecessary client disconnection. Examples include warehouses that use barcode scanners. Barcode scanners can be silent (non-chatty) to conserve battery power and communicate only if required. In these conditions, if the scanner gets disconnected, it has to reconnect back which will be unacceptable. For such SSIDs, raising inactivity timeout value is suggested.

We can find inactivity field in Zonedirector under WLAN configuration. <Configure --> WLANs --> Select the WLAN Affected --> Advanced Options Inactivity timeout>

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