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486 | RSTP DellPowerConnectW-SeriesArubaOS6.2 | User Guide
STP (802.1d)
Port State
RSTP (802.1w)
Port State
Listening Discarding
Learning Learning
Forwarding Forwarding
In addition to port state changes, RSTP introduces port roles for all the interfaces (see Table 146).
RSTP (802.1w)
Port Role
Description
Root The port that receives the best BPDU on a bridge.
Designated The port can send the best BPDU on the segment to which it is connected.
Alternate The port offers an alternate path, in the direction of root bridge, to that provided by bridge’s root
port.
Backup The port acts as a backup for the path provided by a designated port in the direction of the spanning
tree.
Table 146:
Port Role Descriptions
The show spantree command (configuration mode) output reveals the state and port role.
(host) (config) #show spantree
Designated Root MAC 00:0b:86:50:3c:20
Designated Root Priority 32768
Root Max Age 20 sec Hello Time 2 sec Forward Delay 15 sec
Bridge MAC 00:0b:86:50:3c:20
Bridge Priority 32768
Configured Max Age 20 sec Hello Time 2 sec Forward Delay 15 sec
Rapid Spanning-Tree port configuration
--------------------------------
Port State Cost Prio PortFast P-to-P Role
---- ----- ---- ---- -------- ------ ----
FE 1/0 Discarding 0 128 Disable Enable Disabled
FE 1/1 Forwarding 0 128 Disable Enable Designated
FE 1/2 Forwarding 0 128 Disable Enable Root
FE 1/3 Discarding 0 128 Disable Disable Disabled
FE 1/4 Discarding 0 128 Disable Enable Alternate
Also, the show spanning-tree interface command indicates the state and roles; see the partial output below.
(host) #show spanning-tree interface fastethernet 1/1
Interface FE 1/7 (port 8) in Spanning tree is FORWARDING
Port path cost 19, Port priority 128 Role DESIGNATED