S
UMMIT
S
WITCH
I
NSTALLATION
AND
U
SER
G
UIDE
7-3
STP C
ONFIGURATIONS
Two STPDs are deÞned:
¥
STPD1 contains VLANs
Sales
and
Personnel.
¥
STPD2 contains VLANs
Manufacturing
and
Engineering.
The VLAN
Marketing
is not assigned to a STPD.
Figure 7-1: Multiple Spanning Tree Domains
When this conÞgurationÕs Switches start up, STP conÞgures each STP domain such that
there are no active loops in the topology. STP could conÞgure 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 any STPD, communicates using
all Þve 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 Page 3 Thursday, September 25, 1997 12:33 PM
