Brocade Communications Systems Brocate Ethernet Access Switch 6910 - Manual (Page 388)

338 Brocade 6910 Ethernet Access Switch Configuration Guide
53-1002581-01
Spanning Tree Commands
18
Default Setting
rstp
Command Mode
Global Configuration
Command Usage
• Spanning Tree Protocol
This option uses RSTP set to STP forced compatibiltiy mode. It uses RSTP for the internal state
machine, but sends only 802.1D BPDUs. This creates one spanning tree instance for the entire
network. If multiple VLANs are implemented on a network, the path between specific VLAN
members may be inadvertently disabled to prevent network loops, thus isolating group
members. When operating multiple VLANs, we recommend selecting the MSTP option.
• Rapid Spanning Tree Protocol
RSTP supports connections to either STP or RSTP nodes by monitoring the incoming protocol
messages and dynamically adjusting the type of protocol messages the RSTP node transmits,
as described below:
• STP Mode – If the switch receives an 802.1D BPDU after a port’s migration delay timer
expires, the switch assumes it is connected to an 802.1D bridge and starts using only
802.1D BPDUs.
• RSTP Mode – If RSTP is using 802.1D BPDUs on a port and receives an RSTP BPDU after
the migration delay expires, RSTP restarts the migration delay timer and begins using
RSTP BPDUs on that port.
• Multiple Spanning Tree Protocol
• To allow multiple spanning trees to operate over the network, you must configure a related
set of bridges with the same MSTP configuration, allowing them to participate in a specific
set of spanning tree instances.
• A spanning tree instance can exist only on bridges that have compatible VLAN instance
assignments.
• Be careful when switching between spanning tree modes. Changing modes stops all
spanning-tree instances for the previous mode and restarts the system in the new mode,
temporarily disrupting user traffic.
Example
The following example configures the switch to use Rapid Spanning Tree:
Console(config)#spanning-tree mode rstp
Console(config)#