User's Manual

S PANNING T REE A LGORITHM C ONFIGURATION
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Configuring Interface Settings for MSTP
You can configure the STA interface settings for an MST Instance using
the MSTP Port Configuration and MSTP Trunk Configuration pages.
Field Attributes
The following attributes are read-only and cannot be changed:
• STA State – Displays current state of this port within the Spanning Tree.
(See Displaying Interface Settings on page 3-165 for additional
information.)
• Discarding - Port receives STA configuration messages, but does not
forward packets.
• Learning - Port has transmitted configuration messages for an interval
set by the Forward Delay parameter without receiving contradictory
information. Port address table is cleared, and the port begins learning
addresses.
• Forwarding - Port forwards packets, and continues learning
addresses.
• Trunk – Indicates if a port is a member of a trunk
13
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The following interface attributes can be configured:
• MST Instance ID – Instance identifier to configure. (Range: 0-4094;
Default: 0)
• Priority – Defines the priority used for this port in the Spanning Tree
Protocol. If the path cost for all ports on a switch are the same, the port
with the highest priority (i.e., lowest value) will be configured as an active
link in the Spanning Tree. This makes a port with higher priority less
likely to be blocked if the Spanning Tree Protocol is detecting network
loops. Where more than one port is assigned the highest priority, the port
with lowest numeric identifier will be enabled.
- Default: 128
- Range: 0-240, in steps of 16
• MST Path Cost – This parameter is used by the MSTP to determine the
best path between devices. Therefore, lower values should be assigned to
ports attached to faster media, and higher values assigned to ports with
slower media. (Path cost takes precedence over port priority.) Note that
13. STA Port Configuration only