Netgear XCM8810 Chassis User Manual - Page 539

NETGEAR 8800 User Manual • Engineering is the carrier VLAN on STPD2. • Marketing is a member of both STPD1 and STPD2 and is a protected VLAN. Sales, Personnel, Marketing Switch A Manufacturing, Engineering, Marketing Switch Y Switch B STPD 1 Switch Z STPD 2 Switch M Sales, Personnel, Manufacturing, Engineering, Marketing EX_048 Figure 35. Multiple STPDs When the switches in this configuration boot-up, STP configures each STPD such that the topology contains no active loops. STP could configure the topology in a number of ways to make it loop-free. In Figure 35, 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 protected VLAN Marketing, which has been assigned to both STPD1 and 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. Within a single STPD, you must be extra careful when configuring your VLANs. Figure 36 illustrates a network that has been incorrectly set up using a single STPD so that the STP configuration disables the ability of the switches to forward VLAN traffic. Chapter 18. STP | 539