Brocade 6910 Ethernet Access Switch Configuration Guide (Supporting R2.2.0.0) - Manual (Page 851)

Brocade 6910 Ethernet Access Switch Configuration Guide 795
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Configuring Interface Settings for STA
• 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 Path Cost – This parameter is used by the STA 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. Note that path cost takes precedence over
port priority. (Range: 0 for auto-configuration, 1-65535 for the short path cost method
16 ,
1-200,000,000 for the long path cost method)
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.
• Admin Link Type – The link type attached to this interface.
• Point-to-Point – A connection to exactly one other bridge.
• Shared – A connection to two or more bridges.
• Auto – The switch automatically determines if the interface is attached to a point-to-point
link or to shared media. (This is the default setting.)
• Root Guard – STA allows a bridge with a lower bridge identifier (or same identifier and lower
MAC address) to take over as the root bridge at any time. Root Guard can be used to ensure
that the root bridge is not formed at a suboptimal location. Root Guard should be enabled on
any designated port connected to low-speed bridges which could potentially overload a slower
link by taking over as the root port and forming a new spanning tree topology. It could also be
used to form a border around part of the network where the root bridge is allowed. (Default:
Disabled)
16. Refer to “Configuring Global Settings for STA” on page 789 for information on setting the path cost
method.
TABLE 160 Recommended STA Path Cost Range
Port Type IEEE 802.1D-1998 IEEE 802.1w-2001
Ethernet 50-600 200,000-20,000,000
Fast Ethernet 10-60 20,000-2,000,000
Gigabit Ethernet 3-10 2,000-200,000
TABLE 161 Default STA Path Costs
Port Type Short Path Cost
(IEEE 802.1D-1998) Long Path Cost
(802.1D-2004)
Ethernet 65,535 1,000,000
Fast Ethernet 65,535 100,000
Gigabit Ethernet 10,000 10,000