You can deploy Branch Gateway in a LAN using RSTP and switch redundancy configuration. You can connect each Ethernet LAN port on the front panel of the Branch Gateway to an external LAN switch.

Spanning tree protocol blocks one of the links from Branch Gateway to the external LAN switch. Spanning tree protocol must be configured on both the external LAN switch and the Ethernet LAN ports on the Branch Gateway. When the gateway determines a primary link failure or malfunction of the switch attached to it, the gateway automatically fails over to the secondary link to the backup switch. Both LAN ports of the peer LAN switch ports must be enabled for the gateway to fail over to the secondary link.

Compared to port redundancy method, Fast RSTP is better because Fast RSTP controls the state of the link between the gateway and the LAN switch based on the best LAN topology. However, Fast RSTP can have a time delay during RSTP convergence.