Introduction to Flex Connect mode in Cisco Catalyst 9800 wireless controllers

Introduction to Flex Connect mode in Cisco Catalyst 9800 wireless controllers

In Flex Connect mode, Cisco Catalyst 9800 wireless controllers can manage wireless access points (APs) centrally while still allowing for local switching and authentication.

It is useful in situations with WAN outages, when remote APs need to operate independently of the main network but still allow centralized management.

Fig 1.1- Flex Connect with Cisco Catalyst 9800

A Flex Connect access point switches to standalone mode anytime it disconnects from a controller. The centrally switched clients are separated from one another. Locally switched customers are still provided with service by the Flex Connect access point, though. 

All clients are disconnected and required to authenticate once more when the Flex Connect access point reconnects to the controller (or a standby controller). This feature has been improved, and customers now experience smooth connectivity while the link between them and the Flex Connect access points is kept intact. 

The connection between the clients and APs is maintained when both the access point and the controller have the same configuration.

The controller does not restore the client's original attributes once the client connection has been made. Only once the session duration expires are the client username, current rate and supported rates, and listen interval settings reset to the original or newly defined values.

To an access point, the controller can send multicast packets in the form of unicast or multicast packets. An access point can only receive multicast packets in Flex Connect mode.

A flex connect site can be specified in the Cisco Catalyst 9800 Series wireless Controller. A flex connect profile may be linked to a flex connect site. For each Flex Connect site, a maximum of 100 access points are permitted.

One-to-one network address translation (NAT) setup is supported by Flex Connect access points. Aside from full multicast, they also enable port address translation (PAT) for all functionalities. If the Unicast option is selected during configuration, multicast is supported across NAT boundaries. 

A many-to-one NAT or PAT barrier is likewise supported by Flex Connect access points, with the exception of situations where you need real multicast to function for all centrally switched WLANs.

On Flex Connect access points, bridges for workgroups and universal workgroups are supported for locally switched clients.

Similar to an IPv4 operation, Flex Connect enables IPv6 clients by bridging the traffic to a local VLAN. For a collection of up to 100 access points, Flex Connect provides Client Mobility.

When switching from local mode to Flex Connect mode and vice versa, an access point does not need to reboot.

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