Cisco Systems WSC4500X16SFP Manual De Usuario
15-4
Software Configuration Guide—Release 12.2(25)SG
OL-7659-03
Chapter 15 Understanding and Configuring Multiple Spanning Trees
Overview of MST
RSTP Port States
The port state controls the forwarding and learning processes and provides the values of discarding,
learning, and forwarding.
learning, and forwarding.
shows the STP port states and RSTP port states.
In a stable topology, RSTP ensures that every root port and designated port transitions to the forwarding
state while all alternate ports and backup ports are always in the discarding state.
state while all alternate ports and backup ports are always in the discarding state.
MST-to-SST Interoperability
A virtual bridged LAN may contain interconnected regions of SST and MST bridges.
shows
this relationship.
Figure 15-1 Network with Interconnected SST and MST Regions
Table 15-1 Comparison Between STP and RSTP Port States
Operational Status
STP Port State
RSTP Port State
Port Included in Active Topology
Enabled
Blocking
1
1.
IEEE 802.1D port state designation.
Discarding
2
2.
IEEE 802.1w port state designation. Discarding is the same as blocking in MST.
No
Enabled
Listening
Discarding
No
Enabled
Learning
Learning
Yes
Enabled
Forwarding
Forwarding
Yes
Disabled
Disabled
Discarding
No
MST
Region
Region
MST
Region
Region
SST
Region
Region
SST
Region
Region
F
F
F
F
F
F
R
F
F
F
F
F
F
F
B
B
B
B
B
r
r
r
r
r
r
r
b
b
F/f = Forwarding
B/b = Blocking
R = Root Bridge
r = Root port
B/b = Blocking
R = Root Bridge
r = Root port
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