3Com 9100 User Manual page 93

Marketing & Sales
Switch 1
Sales & Engineering
Figure 17 Tag-based STP configuration
The tag-based network in
Switch 1 contains VLAN Marketing and VLAN Sales .
Switch 2 contains VLAN Engineering and VLAN Sales .
Switch 3 contains VLAN Marketing , VLAN Engineering , and VLAN
Sales .
The tagged trunk connections for three switches form a triangular
loop that is not permitted in an STP topology.
All VLANs in each switch are members of the same STPD.
STP may block traffic between Switch 1 and Switch 3 by disabling the
trunk ports for that connection on each switch.
Switch 2 has no ports assigned to VLAN marketing. Therefore, if the
trunk for VLAN marketing on Switches 1 and 3 is blocked, the traffic for
VLAN marketing will not be able to traverse the switches.
Marketing, Sales & Engineering
Switch 2
Figure 17 has the following configuration:
STP Configurations 93
Switch 3
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