How Do I Use FTOS to Configure Spanning Tree?
 

Overview

FTOS supports four flavors of Spanning Tree Protocol (STP) -- standard STP, MSTP, PVST+, and RSTP -- all of which are disabled by default. Two STP protocols cannot be enabled at the same time.

Step 1: Enable STP.

Enabling STP consists of enabling the desired protocol globally. All enabled Layer 2 interfaces are automatically included in the topology.  

(Force10) #configure     
(Force10) (conf)#protocol spanning-tree {0|mstp|pvst|rstp}
(Force10) (conf-span)#no disable

You would then add to the selected topology any desired Layer 2 interfaces that were enabled after the protocol was enabled. In INTERFACE mode, use:

STP: spanning-tree 0 [cost cost] [portfast [bpduguard]] [priority priority]
PVST+: spanning-tree pvst [edge-port [bpduguard]] | vlan vlan-range {cost cost |
priority value}]
MSTP: spanning-tree
RSTP: spanning-tree rstp {cost cost | edge-port [bpduguard] | priority priority}

Step 2: Verify the Global Configuration. 

You can use the show config command in the selected STP mode to verify that the STP protocol is enabled, or use the appropriate show spanning-tree command, in EXEC privilege mode, for the selected STP protocol:

STP: show spanning-tree 0 [active | brief | interface interface | root | summary]
PVST+: show spanning-tree pvst [vlan vlan-id] [brief] [interface]
RSTP: show spanning-tree rstp [brief]
MSTP: show spanning-tree mst configuration
MSTP: show spanning-tree msti [instance-number [brief]]

For example, for standard STP:

(Force10) #show spanning-tree 0
         
Executing IEEE compatible Spanning Tree Protocol
Bridge Identifier has priority 32768, Address 0001.e800.0a56
Configured hello time 2, max age 20, forward delay 15
We are the root of the spanning tree
Current root has priority 32768 address 0001.e800.0a56
Topology change flag set, detected flag set
Number of topology changes 1 last change occurred 0:00:05 ago
from GigabitEthernet 1/3
Timers: hold 1, topology change 35
hello 2, max age 20, forward_delay 15
Times: hello 1, topology change 1, notification 0, aging 2
Port 26 (GigabitEthernet 1/1) is Forwarding
Port path cost 4, Port priority 8, Port Identifier 8.26
Designated root has priority 32768, address 0001.e800.0a56
Designated bridge has priority 32768, address 0001.e800.0a56
Designated port id is 8.26, designated path cost 0
Timers: message age 0, forward_delay 0, hold 0
Number of transitions to forwarding state 1
BPDU: sent:18, received 0
The port is not in the portfast mode
Port 27 (GigabitEthernet 1/2) is Forwarding
Port path cost 4, Port priority 8, Port Identifier 8.27
Designated root has priority 32768, address 0001.e800.0a56
Designated bridge has priority 32768, address 0001.e800.0a56
Designated port id is 8.27, designated path cost 0
Timers: message age 0, forward_delay 0, hold 0
Number of transitions to forwarding state 1
BPDU: sent:18, received 0
The port is not in the portfast mode
Port 28 (GigabitEthernet 1/3) is Forwarding
Port path cost 4, Port priority 8, Port Identifier 8.28
Designated root has priority 32768, address 0001.e800.0a56
Designated bridge has priority 32768, address 0001.e800.0a56
Designated port id is 8.28, designated path cost 0
Timers: message age 0, forward_delay 0, hold 0
Number of transitions to forwarding state 1
BPDU: sent:31, received 0
The port is not in the portfast mode

Step 3: Verify the Interface Configuration.

To verify that a particular interface is included in the STP topology, you can use the appropriate show spanning-tree command, as above. The output in the example, above, includes Spanning Tree details for ports 1/1, 1/2, and 1/3.

You can also use the brief option in each show spanning-tree command to get an overview of the enabled ports. Here is example output for a standard STP topology:

Force10#show span 0 brief
Executing IEEE compatible Spanning Tree Protocol
Root ID Priority 32768
Address 0001.e800.0a56
Root Bridge hello time 2, max age 20, forward delay 15
Bridge ID Priority 32768,
Address 0001.e800.0a56
Configured hello time 2, max age 20, forward delay 15
Interface Designated
Name PortID Prio Cost Sts Cost Bridge ID PortID
-------------- ------ ---- ---- --- ----- ----------------- ------
Gi 1/1 8.26 8 4 FWD 0 32768 0001.e800.0a56 8.26
Gi 1/2 8.27 8 4 FWD 0 32768 0001.e800.0a56 8.27
Gi 1/3 8.28 8 4 FWD 0 32768 0001.e800.0a56 8.28
Force10#

Information to Collect if You Open a TAC Case

If you would like assistance from Force10 Networks after following the steps above, please use the Create Service Request form on the iSupport page and include the following information if available:

  • Console captures showing the steps taken
  • Output from the show tech-support command to capture the installed hardware and the SFTOS version
  • Network diagrams or other descriptions of the network design, including VLAN configurations and IP address ranges
 
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