Over the DS

[Moudar]

Hi,

When configuring FT which to choose over-the-ds or over-the-air?

Can you explain the difference and which is better.

[Mark Elsen]

 - FYI : https://www.cisco.com/c/dam/en/us/td/docs/wireless/controller/technotes/80211r-ft/b-80211r-dg.html#:~:text=Over%2Dthe%2DAir%E2%80%94The,AP%20through%20the%20current%20AP.

 M.

[Karsten Iwen]

"Over the ds" seems more elegant as we use our existing connection to start the roaming process. But in some occasions (non optimal roaming design), the client could lose the connection to the actual AP which makes "over the ds" non-working and the client had to go through the whole Auth-process on the new AP again. With "over the air" the fast transition still can take place as the new AP is all that is needed.

[Moudar]

In a Cisco book (300-425) it says:

"In practice, over-the-DS is rarely implemented and used by clients"

So should we avoid it completely? What is a good defination of "non optimal roaming design"?

[Karsten Iwen]

Non optimal would be where you walk along a hallway, turn around the corner and lose the connection to the previous AP.