Disabling Spanning Tree on the Ethernet Switch

Spanning tree is enabled by default on Cisco switches. If you add a switch with spanning tree enabled to the network, then you might cause network problems. As a precaution, you can disable spanning tree from the uplink port VLAN before connecting the switch to the network. Alternatively, you can turn on spanning tree protocol with specific protocol settings either before or after connecting to the network.

To disable spanning tree on the uplink port VLAN:

1. Disable spanning tree on the uplink port VLAN:

   rasw-ip# configure terminal
   Enter configuration commands, one per line. End with CNTL/Z.
   rasw-ip(config)# no spanning-tree vlan 1
   rasw-ip(config)# end
   rasw-ip# write memory
   Building configuration...
   Compressed configuration from 2654 bytes to 1163 bytes[OK]
   

2. Verify that spanning tree is disabled:

   rasw-ip# show spanning-tree vlan 1
   Spanning tree instance(s) for vlan 1 does not exist.
   

To re-enable spanning tree protocol with the default protocol settings:

• Use the commands shown in this example:

  ra1sw-ip# configure terminal
  Enter configuration commands, one per line. End with CNTL/Z.
  ra1sw-ip(config)# spanning-tree vlan 1
  ra1sw-ip(config)# end
  ra1sw-ip# write memory

See Also:

Cisco Switch Configuration Guide to enable spanning tree protocol with the specific protocol settings required by the data center Ethernet network