Cisco 3850 Fast SSID

[Roger Alderman]

Hi all

Can anyone confirm that the fast SSID change feature on a Cisco 3850 actually works?
I have set wireless client fast-SSID-change as a global command.

If the client tries to switch between SSIDs he is still being cached on the 3850 and can't connect to the second SSID until he has disappeared from the cache.

Regards

Roger

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[Scott Fella]

Don't have one up and running right now to test, but is it all clients having this issue.

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[Roger Alderman]

Yes it is all clients.
Until the client has disappeared from show wireless client summary, you can't connect to the other SSID successfully.

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[Scott Fella]

I'll have time to test it later in the week.

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[Roger Alderman]

Thanks Scott - appreciate it.
I'm using 3.03.00SE code.

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[Scott Fella]

I'll ask some of my peers who also has installs this week. You have your 3850 as a MO and multiple MA's?

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[Roger Alderman]

No - just a single 3850 working as an MC.
Incidentally I've seen the same issue on a 5760 operating as an MC.

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[Scott Fella]

Okay.... well I guess I can try both, just that my 5760 has beta code so that really won't help.

Thanks,

Scott

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[pcgndelgado]

I have 5760 WLCs now running IOS XE 3.3.1 and have the same problem.  I first noticed this issue on 3.3.0. 

We send authentication/authorization to Cisco ISE.  What I'm seeing is that when Fast SSID is enabled and I try to connect to a second SSID, the WLC sends the SSID from the last WLAN to ISE.  This causes authentication to fail on ISE since the policy rules don't match the wrong SSID that's sent.  When Fast SSID is disabled, it works just fine.

[Saurav Lodh]

"When fast SSID changing is enabled, the  controller   allows clients  to move faster between SSIDs. When the client sends a  new association  for a different SSID, the client entry in the controller  connection  table is cleared before the client is added to the new SSID.  This  happens when fast SSID is disabled.

With fast SSID enabled, the client entry is not cleared  and the delay is not enforced .When fast SSID changing is disabled, the  controller  enforces a delay before clients are allowed to move to a new  SSID."

Therefore, inorder to have entry cleared so that fresh entry takes the place, disable fast SSID. Here fast signifies the delay which is inccured in this updating entry.

[Roger Alderman]

Hi Saurav

Your response is somewhat confusing. Please review your response as it it contradictory in every way.

Fast SSID should mean that the client entry is immediately deleted if he joins a new SSID. If Fast SSID id disabled then the client entry is cached for a period of time.

My original observation was that with Fast SSID enabled the client entry is still being cached when it shouldn't be.

This is no different to the Fast SSID function on a 5508 controller. If you want the client entry to be deleted when he switches SSIDs you enable Fast SSID. You don't disable it.

Regards

Roger

[Abhishek Abhishek]

Please go through the link for information on which network modules fast SSID works-

http://www.cisco.com/en/US/docs/switches/lan/catalyst3850/software/release/3se/release_notes/OL_28114.html#wp206840

Hope this will help you.

[Roger Alderman]

So having tried this on a 3850 it looks like the situation is:

If you want Fast SSID functionality - make sure Fast SSID is disabled.

If you don't want Fast SSID functionality - make sure Fast SSID is enabled.

Go figure that one!

[Scott Fella]

That's wrong... I have enabled fast SSID change on my customers and able to change SSID's quickly...

Thanks,

Scott

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[Roger Alderman]

Scott

There is a reply within this thread from a Cisco guy who suggests that it works the wrong way round.

I've tried it on a 5760 and 2 x 3850s now and someone earlier in the thread has seen it as well.

With my latest 3850 installation I've tested it with clients and with fast SSID enabled the client details remain cached and you can't reconnect until the cache entry clears. Switch off fast SSID and the entry gets deleted as soon as the client disconnects and breaks the association.

I'm not happy with it either as it doesn't make sense. I'm with Cisco on Monday so I'll investigate further.