Local mode AP vs central switched FlexConnect AP

[a1111]

Hello,

Can someone please help me with the following?

What's the difference between a local mode AP and a FlexConnect AP that does central switching?

Both of them have CAPWAP data and control tunnels to the WLC, and neither of them work if the connection to the WLC is down.

The only difference seems to be that a central switched FlexConnect AP can have local switching configured as a fallback -- but that's optional.

But then, when would you use local mode AP instead of a central switched FlexConnect AP?

Is a local mode AP just a central switched FlexConnect AP that's easier to configure? So the benefit of a central switched FlexConnect AP is less headache for the IT team, as well as for everyone else if the IT team makes a mistake and causes some issues?

Thanks.

[M02@rt37]

Hello @a1111 

The key diference lies in what happen when the WLC become unreachable. A local mode AP simply stops functioning—clients are dropped, and the AP becomes inactive. In contrast, a Flexconnect AP can be configured with a fallback mechanism that allows it to switch SSIDs to local mode and maintain client connectivity even during a WAN or WLC outage.

Flexconnect was specifically designed for branch or remote locations where WLC conectivity may be over a WAN and not always reliable. So, while a Flexconnect AP with central switching may behave like a local mode AP under normal conditions, it offers the option to locally switch traffic or failover during outages.

[a1111]

Hello,

Thank you. Yes, I know that. However, when would you use local mode AP instead of a central switched FlexConnect AP? It seems like there's no good use case for that instead of central switched FC with the optional fallback configured.

[M02@rt37]

@a1111 

It is a question of design. This choice hinges on various factors, including network topology, performance requirements, feature needs? and operational considerations...

In centralized deployment, such as large campus, local mode is often preferred. In this configuration, all client traffic is tunneled back to the controller, facilitating centralized management and seamless client roaming across access points.

However, local mode relies heavily on the controller's availability; if the controller becomes unreachable, access points in local mode may cease to function properly.

Conversely, Flexconnect mode is designed for remote or branch sites where deploying a local controller may not be feasible. In Flexvonnect mode, AP can switch client data trafic locally, reducing WAN Bw usage and allowing continued operation even if the connection to the central controler is lost.

[a1111]

Thanks. Yes, that part is clear. 

But if both Local Mode and FlexConnect (with central switching) behave the same, then what’s the point of using Local Mode? Why not just always use FlexConnect with optional fallback?

[M02@rt37 · Accepted solution]

@a1111 

Some advanced features available in centralized deployments might not be fully supported in Flexconnect mode. 

[Rich R · Accepted solution]

That last point M02@rt37 made is the key one - there are certain features which are only supported on Local Mode APs. (doesn't make much sense in my opinion but that's the way it is)

Also, Local Mode and Flexconnect Central Switching are not 100% identical - there are some small technical differences under the covers.  For example we use MAB + Web auth for remote sites where client association depends on the MAB radius reply before fallback to web auth.  In Local Mode that will sometimes timeout before the AP gets the radius reply and client association fails.  By switching to Flexconnect Mode (still central switching) the AP increases the timer and allows the client to associate while waiting for the reply.  These timers and behaviour are not otherwise tuneable and this is how TAC/BU told us to solve the association timeouts. So now all our APs are set to Flexconnect Mode even if they only have centrally switched WLANs.

As to the use case - we have some SSID (WLAN) which are centrally switched and some which are locally switched (on the same APs) so that necessarily requires the AP to be in Flexconnect Mode too.

[a1111]

Thank you.

So then I was wrong, and the statement "local mode AP just a central switched FlexConnect AP that's easier to configure" is false.

Then these differences are incidental? In other words, they have nothing to do with the common behavior of local mode APs and central switched FC APs without a fallback configured, which is that both send user traffic via their CAPWAP data tunnel to the WLC? So they have these other differences because of unrelated reasons? It's just a design choice that cisco made?

[Rich R]

Yes I'd say that's about right <smile>