Extreme Networks ExtremeWare XOS Guide Manual page 432

Spanning Tree Protocol
Figure 33: Incorrect tag-based STPD configuration
Marketing & Sales
Switch 1
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 can 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.
NOTE
If an STPD contains multiple VLANs, all VLANs should be configured on all ports in that domain, except for ports
that connect to hosts (edge ports).
432
Marketing, Sales & Engineering
Switch 2
Sales & Engineering
Figure 33 has the following configuration:
Switch 3
EX_049
ExtremeWare XOS 11.3 Concepts Guide