78To do… Use the command… RemarksPerform mCheck stp mcheck RequiredNOTE:An mCheck operation takes effect on a device that operates in MSTP, RSTP, or PVST mode.Configuring the VLAN Ignore featureTraffic of a VLAN on a complex network may be blocked by the spanning tree.Figure 18 VLAN connectivity blocked by MSTPAs shown in Figure 18:• Port A1 on Device A allows the traffic of VLAN 1 to pass through, and Port A2 allows the traffic ofVLAN 2 to pass through.• Port B1 on Device B allows the traffic of VLAN 1 to pass through, and Port B2 allows the traffic ofVLAN 2 to pass through.• Device A and Device B run a spanning tree protocol. Device A is the root bridge, and Port A1 andPort A2 are designated ports. On Device B, Port B1 is the root port, and port B2 is the blocked port.Traffic of VLAN 2 is blocked.• Enabling the VLAN Ignore feature for a VLAN can make ports of the VLAN forward packetsnormally rather than comply with the spanning tree calculation result.Configuring the VLAN Ignore featureFollow these steps to configure VLAN Ignore:To do… Use the command… RemarksEnter system view system-view —Enable VLAN Ignore for thespecified VLANs stp ignored vlan vlan-listRequiredBy default, VLAN Ignore isdisabled.Display VLAN Ignore-enabledVLANsdisplay stp ignored-vlan [ | { begin| exclude | include }regular-expression ]OptionalAvailable in any viewVLAN Ignore configuration example1. Network requirements
