Alcatel-Lucent 6850-48 ネットワークガイド
Configuring STP Port Parameters
Configuring Spanning Tree Parameters
page 13-32
OmniSwitch AOS Release 6 Network Configuration Guide
September 2009
By default, Spanning Tree is enabled on a port and the path cost is set to zero. If the switch is running in
the 1x1 Spanning Tree mode, then the port path cost applies to the specified VLAN instance associated
with the port. If the switch is running in the flat Spanning Tree mode, then the port path cost applies across
all VLANs associated with the port. The flat mode instance is specified as the port’s instance, even if the
port is associated with other VLANs.
the 1x1 Spanning Tree mode, then the port path cost applies to the specified VLAN instance associated
with the port. If the switch is running in the flat Spanning Tree mode, then the port path cost applies across
all VLANs associated with the port. The flat mode instance is specified as the port’s instance, even if the
port is associated with other VLANs.
To change the port path cost value for a VLAN instance, specify a VLAN ID with the
command when the switch is running in the 1x1 mode. For example, the following command
configures a 16-bit path cost value for port 8/1 for VLAN 10 to 19 (the port speed is 100 MB, 19 is the
recommended value).
recommended value).
-> bridge 10 8/1 path cost 19
The explicit
command configures the port path cost value for a VLAN
instance when the switch is running in either mode (1x1 or flat). For example, the following command
performs the same function as the command in the previous example:
performs the same function as the command in the previous example:
-> bridge 1x1 10 8/1 path cost 19
To change the port path cost value for the flat mode instance, use either the
command or the
command. Note that both commands are available when
the switch is running in either mode (1x1 or flat) and an instance number is not required. For example, the
following commands configure a 32-bit path cost value for port 1/24 for the flat mode instance to 20,000
(the port speed is 1 GB, 20,000 is the recommended value):
following commands configure a 32-bit path cost value for port 1/24 for the flat mode instance to 20,000
(the port speed is 1 GB, 20,000 is the recommended value):
-> bridge 1/24 path cost 20000
-> bridge cist 1/24 path cost 20000
As in previous releases, it is possible to configure the flat mode instance with the bridge slot/port path
cost command by specifying 1 as the instance number (e.g., bridge 1 1/24 path cost 19). However, this is
only available when the switch is already running in the flat mode and STP or RSTP is the active protocol.
cost command by specifying 1 as the instance number (e.g., bridge 1 1/24 path cost 19). However, this is
only available when the switch is already running in the flat mode and STP or RSTP is the active protocol.
The port path cost value is also configurable for a Multiple Spanning Tree Instance (MSTI). To configure
this value for an MSTI, use the explicit
this value for an MSTI, use the explicit
command and specify the MSTI
ID for the instance number. For example, the following command configures the path cost value for port 1/
12 for MSTI 10 to 19:
12 for MSTI 10 to 19:
-> bridge msti 10 1/12 path cost 19
Note that when MSTP is the active flat mode protocol, explicit Spanning Tree bridge commands are
required to configure parameter values. Implicit commands are for configuring parameters when the STP
or RSTP protocols are in use. See
required to configure parameter values. Implicit commands are for configuring parameters when the STP
or RSTP protocols are in use. See
for more
information.
Path Cost for Link Aggregate Ports
Physical ports that belong to a link aggregate do not participate in the Spanning Tree Algorithm. Instead,
the algorithm is applied to the aggregate logical link (virtual port) that represents a collection of physical
ports. By default, Spanning Tree is enabled on the aggregate logical link and the path cost value is set to
zero.
the algorithm is applied to the aggregate logical link (virtual port) that represents a collection of physical
ports. By default, Spanning Tree is enabled on the aggregate logical link and the path cost value is set to
zero.
If a 32-bit path cost value is in use and the path_cost for a link aggregate is set to zero, the following
default values based on link speed and link aggregate size are used:
default values based on link speed and link aggregate size are used: