This object identifies the module that manages the grouping of vlans in this virtual context. mstp(1) - MSTP(Multiple Spanning Tree Protocol) module manages the grouping of vlans. In this case, MSTI(MSTP instance Id) identifies the group (or vlan list). If a MSTI is mapped to a ring instance, then that ring instance will protect the list of vlan mapped to that MSTI. Administrator should make sure that MSTP module is started and enabled, if this object is set to mstp(1). erps(2) - ERPS module manages the grouping of vlans. If this value is set, then fsErpsVlanGroupTable is used to configure the grouping of vlans. In this case, fsErpsVlanGroupId object identifies the group. If a list is mapped to a ring instance, the ring instance will protect the list of vlans mapped to that list. fsErpsVlanGroupTable can be configured in a virtual context only when this object is set to 'erps'. It is recommended to shutdown erps or delete all rings in this context before changing the value for this context.