Restricted Role is a Spanning Tree protocol feature that allows or disallows the root role on specified ports. When Restricted Role is enabled, the port will not be selected as the root port for the CIST or any MSTI, even if it has the best Spanning Tree priority. A port with Restricted Role enabled is selected as an alternate port after the root port has been selected.
If enabled, Restricted Role can cause lack of Spanning Tree connectivity. Setting Restricted Role to enabled prevents bridges, external to a core region of the network, from influencing the Spanning Tree active topology. You may wish to use Restricted Role when bridges are not under your full control. You may also wish to enable Restricted Role on ports where the bridge is external to the core and where the port faces away from the root, in cases where the port role would normally be designated. This can speed network reconvergence, particularly after loss of the root bridge. Restricted role is disabled by default.