GS-5220-Series User Manual

User’s Manual of GS-5220 Ultra PoE & PoE+ Series
159
 From forwarding to disabled
 From disabled to blocking
Figure 4-7-1: STP Port State Transitions
You can modify each port state by using management software. When you enable STP, every port on every switch in the
network goes through the blocking state and then transitions through the states of listening and learning at power up. If properly
configured, each port stabilizes to the forwarding or blocking state. No packets (except BPDUs) are forwarded from, or received
by, STP enabled ports until the forwarding state is enabled for that port.
2. STP Parameters
STP Operation Levels
The Switch allows for two levels of operation: the switch level and the port level. The switch level forms a spanning tree
consisting of links between one or more switches. The port level constructs a spanning tree consisting of groups of one or more
ports. The STP operates in much the same way for both levels.
On the switch level, STP calculates the Bridge Identifier for each switch and then sets the Root
Bridge and the Designated Bridges.
On the port level, STP sets the Root Port and the Designated Ports.