Technical data

Brocade 6910 Ethernet Access Switch Diagnostic Guide 21
53-1002348-02
Spanning Tree Protocol and derivatives
ports are blocked to prevent loops that might occur within an IST and also throughout the CST. In
addition, MSTP can co-exist with individual devices running STP or RSTP in the Common and
Internal Spanning Tree instance (CIST). With the exception of the provisions for multiple instances,
MSTP operates exactly like RSTP.
STP show commands
show spanning-tree
Syntax: show spanning-tree [brief | ethernet unit/port | port-channel channel-id|
stp-enabled-only]
• brief - Shows a brief summary of STP settings for each port.
• ethernet unit/port - Specifies a port within the VLAN for detailed STP information.
• port-channel channel-id - Specifies a trunk within the VLAN for detailed STP information.
• stp-enabled-only - Shows STP settings for the switch and for STP-enabled ports.
This command displays global settings for STP.
Console# show spanning-tree
Spanning Tree Information
---------------------------------------------------------------
Spanning Tree Mode : STP
Spanning Tree Enabled/Disabled : Enabled
Instance : 0
VLANs Configured : 1-4093
Priority : 32768
Bridge Hello Time (sec.) : 2
Bridge Max. Age (sec.) : 20
Bridge Forward Delay (sec.) : 15
Root Hello Time (sec.) : 2
Root Max. Age (sec.) : 20
Root Forward Delay (sec.) : 15
Max. Hops : 20
Remaining Hops : 20
Designated Root : 32768.0001ECF8D8C6
Current Root Port : 1
Current Root Cost : 100000
Number of Topology Changes : 2
Last Topology Change Time (sec.): 790
Transmission Limit : 3
Path Cost Method : Long
Flooding Behavior : To VLAN
Cisco Prestandard : Disabled
This command displays detailed STP information (in this instance, for Port 1).
Console# show spanning-tree ethernet 1/1
Eth 1/ 1 Information
--------------------------------------------------------------
Admin Status : Enabled
Role : Root
State : Forwarding
Admin Path Cost : 0
Oper Path Cost : 100000
Priority : 128
Designated Cost : 0