Best practice subnet size for gigabit network access layer

Unanswered Question

Well in that kind of a case - you should consider:-

1) WLAN for Phones - which I would strongly recommend for it's own QoS policy, WMM, CAC and AP Load Sharing.

2) not having ALL AP's have ALL WLANS - select which WLANS need to be sent to specific areas for specific AP's. i.e you dont want the Cafe WLAN available from the classrooms (campus examples)

3) Create IP Subnets based on equipment types, WLANS.

Bad practise is to bundle all wireless in one WLAN - bad planning and bad security.


Giuseppe Larosa Thu, 03/12/2009 - 06:13
User Badges:
  • Super Silver, 17500 points or more
  • Hall of Fame,

    Founding Member


I strongly agree with Andrew using a single ip subnet for voip wireless phones and PCs is not recommended.

We have made a deployment using WISMs and several client vlans and it is working well.

Hope to help


Leo Laohoo Thu, 03/12/2009 - 14:39
User Badges:
  • Super Gold, 25000 points or more
  • Hall of Fame,

    The Hall of Fame designation is a lifetime achievement award based on significant overall achievements in the community. 

  • Cisco Designated VIP,

    2017 LAN, Wireless

Have you browsed the Wireless LAN Controller (WLC) Configuration Best Practices (

Joseph W. Doherty Fri, 09/28/2012 - 10:08
User Badges:
  • Super Bronze, 10000 points or more


The  Author of this posting offers the information contained within this  posting without consideration and with the reader's understanding that  there's no implied or expressed suitability or fitness for any purpose.  Information provided is for informational purposes only and should not  be construed as rendering professional advice of any kind. Usage of this  posting's information is solely at reader's own risk.

Liability Disclaimer

In  no event shall Author be liable for any damages whatsoever (including,  without limitation, damages for loss of use, data or profit) arising out  of the use or inability to use the posting's information even if Author  has been advised of the possibility of such damage.


As the other posters have noted, a /24 often is a good starting point for a maximum subnet size.  Occasionally it's too large, and conversely sometimes it can be pushed larger.  The determinate is broadcast volume.

On something like Cisco's WLC and/or WiSM, you can often safely push client subnets larger than a /24 because there's not the same broadcast issue between wireless clients on the same subnet.  If your have "temporary" wireless clients, you might also want to use a much larger subnet to allow for a larger DHCP pool, as IPs can be tied up, with transitiory clients until their lease expires.  (Of course, you can also decrease the lease time to recover inactive IPs faster.)

Recently, I've been involved in a project where we've been migrating multiple internal Wireless (WLC or WiSM) subnets (all same SSID and security) to a single /22 or /21.  So far, we haven't seen any problems, although rarely more than a couple of hundred active wireless client at anyone time.  Definitely, a little easier to manage.


This Discussion