Alcatel-Lucent 6850-48 网络指南
Configuring STP Bridge Parameters
Configuring Spanning Tree Parameters
page 13-20
OmniSwitch AOS Release 6 Network Configuration Guide
September 2009
Selecting the Bridge Protocol
The switch supports four Spanning Tree protocols: STP, RSTP, MSTP, and RRSTP (the default). To
configure the Spanning Tree protocol for a VLAN instance when the switch is running in the 1x1 mode,
enter bridge followed by an existing VLAN ID, then protocol followed by stp or rstp. For example, the
following command changes the protocol to RSTP for VLAN 455:
configure the Spanning Tree protocol for a VLAN instance when the switch is running in the 1x1 mode,
enter bridge followed by an existing VLAN ID, then protocol followed by stp or rstp. For example, the
following command changes the protocol to RSTP for VLAN 455:
-> bridge 455 protocol rstp
Note that when configuring the protocol value for a VLAN instance, MSTP is not an available option. This
protocol is only supported on the flat mode instance.
protocol is only supported on the flat mode instance.
In addition, the explicit
command configures the protocol for a VLAN instance
regardless of which mode (1x1 or flat) is active on the switch. For example, the following command also
changes the protocol for VLAN 455 to RSTP:
changes the protocol for VLAN 455 to RSTP:
-> bridge 1x1 455 protocol rstp
To configure the protocol for the single flat mode instance when the switch is running in either mode (1x1
or flat), use the
or flat), use the
command but do not specify an instance number
.
This command config-
ures the flat mode instance by default, so an instance number is not needed, as shown in the following
example:
example:
-> bridge protocol mstp
As in previous releases, it is possible to configure the flat mode instance with the bridge protocol
command by specifying 1 as the instance number (e.g., bridge 1 protocol rstp). However, this is only
available when the switch is already running in the flat mode and STP or RSTP is the active protocol.
command by specifying 1 as the instance number (e.g., bridge 1 protocol rstp). However, this is only
available when the switch is already running in the flat mode and STP or RSTP is the active protocol.
In addition, the explicit
command configures the protocol for the flat mode instance
regardless of which mode (1x1 or flat) is active on the switch. For example, the following command
selects the RSTP protocol for the flat mode instance:
selects the RSTP protocol for the flat mode instance:
-> bridge cist protocol mstp
Configuring the Bridge Priority
A bridge is identified within the Spanning Tree by its bridge ID (an eight byte hex number). The first two
bytes of the bridge ID contain a priority value and the remaining six bytes contain a bridge MAC address.
bytes of the bridge ID contain a priority value and the remaining six bytes contain a bridge MAC address.
The bridge priority is used to determine which bridge will serve as the root of the Spanning Tree. The
lower the priority value, the higher the priority. If more than one bridge have the same priority, then the
bridge with the lowest MAC address becomes the root.
lower the priority value, the higher the priority. If more than one bridge have the same priority, then the
bridge with the lowest MAC address becomes the root.
Note. Configuring a Spanning Tree bridge instance with a priority value that will cause the instance to
become the root is recommended, instead of relying on the comparison of switch base MAC addresses to
determine the root.
become the root is recommended, instead of relying on the comparison of switch base MAC addresses to
determine the root.
If the switch is running in the 1x1 Spanning Tree mode, then a priority value is assigned to each VLAN
instance. If the switch is running in the flat Spanning Tree mode, the priority is assigned to the flat mode
instance or a Multiple Spanning Tree Instance (MSTI). In both cases, the default priority value assigned is
32768. Note that priority values for an MSTI must be multiples of 4096.
instance. If the switch is running in the flat Spanning Tree mode, the priority is assigned to the flat mode
instance or a Multiple Spanning Tree Instance (MSTI). In both cases, the default priority value assigned is
32768. Note that priority values for an MSTI must be multiples of 4096.