Understanding Flexconnect - Local vs Central Switching, and WLC failover scenario ??

Question

Hello Experts
We have one WLC 5508 in Building1, few 2700 Series AP in Building1, and one 1252AG in Building2. The LAN subnet is same for both Buildings connected via a dark fiber.
My requirement is to have Central Switching in Building1 since WLC is located locally, and Local Switching in Building2 to avoid inter-building traffic, for both Buildings we already one VLAN/IP Subnet. (Both Buildings access resources from a central Datacenter which hosts all the servers.)
Questions:
1. Is the above scenario possible using single SSID ? My understanding is that one WLAN+SSID can't have both Local and Central switching enabled.
2. In Flexconnect Central Switching mode, during WLC failure, does the switching change to Local switching automatically ?
3. When I choose Local Switching for a specific WLAN, does it Locally switch always , or does it Locally switch only when WLC is down ?
4. We want to use Microsoft PEAP using AD User Authentication. When Local Authentication is enabled on WLC, I understand that when WLC fails (and RADIUS Server is still reachable), can we still have the AP directly contact RADIUS server as a direct client and provide 802.1X Microsoft PEAP authentication. Guess this is Primary Backup Radius Server configuration. Is this understanding correct ?
Thanks.

Answer 1

Hi
The LAN subnet is same for both Buildings connected via a dark fiber.
If this is the case there is no need of FlexConnet, as you have enough bandwidth & same L2 extended in those two buildings. Typically FlexConnect is for branch deployment where WAN link bandwidth is a concern.
Anyway if you want to do this & here is the answer for your specific queries.
1. Is the above scenario possible using single SSID ? My understanding is that one WLAN+SSID can't have both Local and Central switching enabled.
You can have both local switching & central switching available for a given SSID. Only FlexConnect mode AP will do Local switching & all Local mode AP will do central switching, though both using the same SSID.
2. In Flexconnect Central Switching mode, during WLC failure, does the switching change to Local switching automatically ?
No, if it is central switching SSID, when WLC is not available client won't able to join this SSID. It is not fall back to Local switching.
3. When I choose Local Switching for a specific WLAN, does it Locally switch always , or does it Locally switch only when WLC is down ?
This is applicable only to FlexConnect mode APs & it always do local switching if that configured. If WLC is not reachable AP will go on "standalone mode" & still do local switching.
4. We want to use Microsoft PEAP using AD User Authentication. When Local Authentication is enabled on WLC, I understand that when WLC fails (and RADIUS Server is still reachable), can we still have the AP directly contact RADIUS server as a direct client and provide 802.1X Microsoft PEAP authentication. Guess this is Primary Backup Radius Server configuration. Is this understanding correct ?
Yes, when this option configured & WLC is not reachable (but RADIUS is reachable) then AP will act as Authenticator & pass radius messages to Auth Server directly.
This is a very good Ciscolive presentation you should see as it describe lots of these features & which WLC codes they introduced.
BRKEWN-2016 - Architecting Network for Branch Offices with Cisco Unified Wireless
HTH
Rasika
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