3Com Switch 8800 Advanced Software V5 Configuration Guide

Configuring the VLAN Ignore Feature 125
c
CAUTION: The stp mcheck command is meaningful only when the device works
in the MSTP (or RSTP) mode, not in the STP-compatible mode.
Configuration example
# Perform mCheck on port Ethernet 1/1/1.
1 Perform mCheck globally
<Sysname> system-view
[Sysname] stp mcheck
2 Perform mCheck in Ethernet interface view
<Sysname> system-view
[Sysname] interface ethernet 1/1/1
[Sysname-Ethernet1/1/1] stp mcheck
Configuring the VLAN
Ignore Feature
Introduction to the
VLAN Ignore Feature
Traffic on a VLAN in a complex network may be blocked by spanning tree.
Figure 30 VLAN connectivity blocked by MSTP
As shown in Figure 30, port A on Switch A allows VLAN 1 to pass, C allows VLAN
2 to pass; port B on Switch B allows VLAN 1 to pass, port D allows VLAN 2 to pass.
Switch A and Switch B run MSTP. Switch A is the root bridge, and port A and port
C on it are designated ports. Port B on Switch B is the root port, and port D is a
blocked port. In this case, traffic on VLAN 2 is blocked.
Enabling the VLAN Ignore feature for a VLAN can make ports of the VLAN forward
packets normally rather than comply with the calculated result of MSTP.
Configuration Procedure Follow these steps to configure VLAN Ignore:
Configuration Examples Network requirements
■ Switch A and B are in direct connection;
To do... Use the command... Remarks
Enter system view system-view -
Enable VLAN Ignore for a
VLAN
stp ignored vlan vlan-list Required
By default, VLAN Ignore is
disabled in a VLAN.
Display VLAN Ignore enabled
VLANs
display stp ignored-vlan Available in any view