Dot11 Guru

Cisco, Troubleshooting

How to decide where to use fast transition

There are 3 main types of clients to consider when thinking about fast transition.

  1. Clients that support 802.11r (Fast Transition).
  2. Clients that do not support 802.11r (Fast Transition) and are not aware of it.
  3. Clients that do not support 802.11r, but are aware of it and are programmed to work around it.

When you configure FT on an SSID, we have to keep these client groups in mind.  It’s quite difficult for us because in many situations, we don’t really know the clients we have.  If we have any client that fits into client group 2, we cannot use FT at all.

  • Only clients from client group 1, enable FT authentication method only.
  • Clients from groups 1 and 2, enable both FT and non-FT authentication methods
  • Clients from group 2, no FT

(forget about adaptive mode, it’s not going to do anything for us here, it’s an apple only thing)

OK, now this is how we decide where to enable and where not to enable within our network:

  • Corporate SSID, enable both.  We assume that all devices will either support or are aware of it.  Laptop refresh policies are common, and we shouldn’t allow unmanage machines to connect
  • Industrial SSID, disabled unless specifically requested and tested.  The devices on this network are not typically replaced often and we have the risk of them not supporting 802.11r at all.
  • Mobile Device SSID, enable both. 
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