Through this variable and others, the SMACF100 supports port- based VLANs. The SMACF100 will pass tags for IEEE 802.3ac VLANs, but will neither insert nor strip them. When this variable is set to block(1), this port may neither transmit packets to nor receive packets from management entities within this switch, i.e. the reporting unit (present in every SMACF100) and the management module (present in SMACF100 Main Management Units). This feature is intended to block traffic between particular Ethernet interfaces inside a single switch; it cannot identify or block management traffic from external sources. A single port is selected for configuration via the slot index. The subdevice index for this variable must always be 1. The logical soundness of VLAN rules cannot be validated. If you set smacf100PBlockMgmt(26) to block(1) on a port that provides a path between a reporting unit and its management module, or between a management module and its Network Management Station, you will be unable to manage the SMACF100 until the situation is rectified (by recabling to work around the misconfiguration, or by resetting the SMACF100 to factory defaults via the serial port).