52Configuring the mode a port uses to recognize/send MSTPpacketsA port can receive/send MSTP packets in the following formats:• dot1s—802.1s-compliant standard format• legacy—Compatible formatBy default, the packet format recognition mode of a port is auto. The port automatically distinguishes thetwo MSTP packet formats, and determines the format of packets it will send based on the recognizedformat.You can configure the MSTP packet format on a port. When working in MSTP mode after theconfiguration, the port sends and receives only MSTP packets of the format you have configured tocommunicate with routers that send packets of the same format.To configure the MSTP packet format to be supported on a port or a group of ports:Step Command Remarks1. Enter system view. system-view N/A2. Enter interface view or portgroup view.• Enter Ethernet interface view orLayer 2 aggregate interface view:interface interface-typeinterface-number• Enter port group view:port-group manualport-group-nameUse one of the commands.3. Configure the mode the port usesto recognize/send MSTPpackets.stp compliance { auto | dot1s |legacy } The default setting is auto.NOTE:• MSTP provides the MSTP packet format incompatibility guard function. In MSTP mode, if a port isconfigured to recognize/send MSTP packets in a mode other than auto, and receives a packet in aformat different from the specified type, the port will become a designated port and remain in thediscarding state to prevent the occurrence of a loop.• MSTP provides the MSTP packet format frequent change guard function. If a port receives MSTP packetsof different formats frequently, the MSTP packet format configuration contains errors. If the port isworking in MSTP mode, it will be shut down for protection. The closed ports can be reactivated after adetection interval. For more information about the detection interval, seeFundamentals ConfigurationGuide.Enabling the spanning tree featureYou must enable the spanning tree feature for the router before any other spanning tree relatedconfigurations can take effect.To enable the spanning tree feature:
