LevelOne GEL-5261, User Manual

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Chapter 7
| Spanning Tree Algorithm
Configuring Interface Settings for MSTP
Configuring Interface Settings for MSTP
Use the Spanning Tree > MSTP (Configure Interface - Configure) page to configure
the STA interface settings for an MST instance.
Parameters
These parameters are displayed:
◆ MST ID – Instance identifier to configure. (Default: 0)
◆ Interface – Displays a list of ports or trunks.
◆ STA Status – Displays the current state of this interface within the Spanning
Tree. (See “Displaying Interface Settings for STA” on page 196 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.
◆ 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)
◆ Admin 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 when the Path
Cost Method is set to short (
page 185 ), the maximum path cost is 65,535.
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 recommended range is listed in Table 11 on page 192 .
The default path costs are listed in Table 12 on page 192 .