SUMMIT SWITCH INSTALLATION AND USER GUIDE 7-3
STP CONFIGURATIONS
Two STPDs are defined:
•STPD1 contains VLANs Sales and Personnel.
•STPD2 contains VLANs Manufacturing and Engineering.
The VLAN Marketing is a member of the default STPD, but not assigned to either
STPD1 or STPD2.
Figure 7-1: Multiple Spanning Tree Domains
When the switches in this configuration start up, STP configures each STP domain such
that there are no active loops in the topology. STP could configure the topology in a
number of ways to make it loop-free.
In Figure 7-1, the connection between Switch A and Switch B is put into blocking state,
and the connection between Switch Y and Switch Z is put into blocking state. After STP
converges, all the VLANs can communicate, and all bridging loops are prevented.
The VLAN Marketing, which has not been assigned to either STPD1 or STPD2,
communicates using all five switches. The topology has no loops, because STP has
already blocked the port connection between Switch A and Switch B, and between
Switch Y and Switch Z.

Sales, Personnel, Marketing

STPD 1 STPD 2

Manufacturing, Engineering, Marketing

Sales, Personnel, Manufacturing, Engineering, Marketing

Switch A Switch Y
Switch Z
Switch M
Switch B
Summit.bk : 7STP.FM Page 3 Thursday, June 18, 1998 9:27 AM