Intel 480T, User Manual

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C H A P T E R 7 Spanning Tree* Protocol (STP)
Figure 12: Multiple Spanning Tree Domains
When the switches in this configuration start up, STP configures
each STPD such that there are no active loops in the topology. STP
can configure the topology in a number of ways to make it loop-
free.
In Figure 12, 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.
Within a single STPD, you must be extra careful when configuring
your VLANs. Figure 13 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.
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
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