Administrator Guide

Designated bridge has priority 32768, address 0001.e801.cbb4
Designated port id is 128.379, designated path cost 0
Number of transitions to forwarding state 1
BPDU : sent 121, received 5
The port is not in the Edge port mode
Port 380 (TenGigabitEthernet 2/4) is designated Forwarding
Port path cost 20000, Port priority 128, Port Identifier 128.380
Designated root has priority 32768, address 0001.e801.cbb4
Designated bridge has priority 32768, address 0001.e801.cbb4
Designated port id is 128.380, designated path cost 0
Number of transitions to forwarding state 1
BPDU : sent 147, received 3
The port is not in the Edge port mode
To conrm that a port is participating in RSTP, use the show spanning-tree rstp brief command from EXEC privilege mode.
R3#show spanning-tree rstp brief
Executing IEEE compatible Spanning Tree Protocol
Root ID Priority 32768, Address 0001.e801.cbb4
Root Bridge hello time 2, max age 20, forward delay 15
Bridge ID Priority 32768, Address 0001.e80f.1dad
Configured hello time 2, max age 20, forward delay 15
Interface Designated
Name PortID Prio Cost Sts Cost Bridge ID PortID
---------- -------- ---- ------- --- ------- ------------- --------
Te 3/1 128.681 128 20000 BLK 20000 32768 0001.e80b.88bd 128.469
Te 3/2 128.682 128 20000 BLK 20000 32768 0001.e80b.88bd 128.470
Te 3/3 128.683 128 20000 FWD 20000 32768 0001.e801.cbb4 128.379
Te 3/4 128.684 128 20000 BLK 20000 32768 0001.e801.cbb4 128.380
Interface
Name Role PortID Prio Cost Sts Cost Link-type Edge
------- --- ------ -------- ---- ------- --- -----------
Te 3/1 Altr 128.681 128 20000 BLK 20000 P2P No
Te 3/2 Altr 128.682 128 20000 BLK 20000 P2P No
Te 3/3 Root 128.683 128 20000 FWD 20000 P2P No
Te 3/4 Altr 128.684 128 20000 BLK 20000 P2P No
R3#
Adding and Removing Interfaces
To add and remove interfaces, use the following commands.
To add an interface to the Rapid Spanning Tree topology, congure it for Layer 2 and it is automatically added. If you previously disabled
RSTP on the interface using the command
no spanning-tree 0 command, re-enable it using the spanning-tree 0 command.
• Remove an interface from the Rapid Spanning Tree topology.
no spanning-tree 0
Modifying Global Parameters
You can modify RSTP parameters.
The root bridge sets the values for forward-delay, hello-time, and max-age and overwrites the values set on other bridges participating in
the Rapid Spanning Tree group.
• Forward-delay — the amount of time an interface waits in the Listening state and the Learning state before it transitions to the
Forwarding state.
• Hello-time — the time interval in which the bridge sends RSTP BPDUs.
• Max-age — the length of time the bridge maintains conguration information before it refreshes that information by recomputing the
RST topology.
NOTE
: Dell Networking recommends that only experienced network administrators change the Rapid Spanning Tree group
parameters. Poorly planned modication of the RSTP parameters can negatively aect network performance.
786 Rapid Spanning Tree Protocol (RSTP)