7-6 CHAPTER 7: SPANNING TREE PROTOCOL (STP)
STP Configurations When you assign VLANs to an STPD, pay careful attention to the STP
configuration and its effect on the forwarding of VLAN traffic.
Figure 7-4 illustrates a network that uses VLAN tagging for trunk
connections. The following four VLANs have been defined:
■ Sales is defined on Switch A, Switch B, and Switch M.
■ Personnel is defined on Switch A, Switch B, and Switch M.
■ Manufacturing is defined on Switch Y, Switch Z, and Switch M.
■ Engineering is defined on Switch Y, Switch Z, and Switch M.
■ Marketing is defined on all Switches (Switch A, Switch B, Switch Y,
Switch Z, and Switch M).
Two STPDs are defined:
■ STPD1 contains VLANs Sales and Personnel.
■ STPD2 contains VLANs Manufacturing and Engineering.
The VLAN Marketing is not assigned to a STPD.
Figure 7-4 Multiple Spanning Tree Domains
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
SW9000.BK Page 6 Wednesday, April 1, 1998 11:00 AM
