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User’s Manual of SGSD-1022 / SGSD-1022P
SGSW-2840 / SGSW-2840P
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connected to two or more bridges.
When automatic detection is selected, the switch derives the link type from the duplex mode. A full-duplex interface is
considered a point-to-point link, while a half-duplex interface is assumed to be on a shared link.
RSTP only works on point-to-point links between two bridges. If you designate a port as a shared link, RSTP is forbidden.
Since MSTP is an extension of RSTP, this same restriction applies.
Example
Console(config)#interface ethernet ethernet 1/5
Console(config-if)#spanning-tree link-type point-to-point
Console(config-if)#
spanning-tree mst cost
This command configures the path cost on a spanning instance in the Multiple Spanning Tree. Use the no form to restore the
default.
Syntax
spanning-tree mst instance_id cost cost no spanning-tree mst instance_id cost
instance_id - Instance identifier of the spanning tree.
(Range: 0-4094, no leading zeroes)
cost - Path cost for an interface.
(Range: 0 for auto-configuration, 1-65535 for short path cost method24, 1-200,000,000 for long path cost method)
The recommended path cost range is listed in Table 4-63 on page 4-211. The recommended path cost is listed in Table
4-64 on page 4-212.
Default Setting
By default, the system automatically detects the speed and duplex mode used on each port, and configures the path cost
according to the values shown below. Path cost “0” is used to indicate auto-configuration mode. When the short path cost
method is selected and the default path cost recommended by the IEEE 8021w standard exceeds 65,535, the default is
set to 65,535. The default path costs are listed in Table 5-65
Command Mode
Interface Configuration (Ethernet, Port Channel)
Command Usage
Each spanning-tree instance is associated with a unique set of VLAN IDs.
This command is used by the multiple spanning-tree algorithm to determine the best path between devices. Therefore,
lower values should be assigned to interfaces attached to faster media, and higher values assigned to interfaces with
slower media.