The following interface attributes can be configured:
• Spanning Tree – Enables/disables STA on this interface. (Default: Ena bled)
• 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 activ e link in the Spanni ng Tree. This
makes a port with higher priority less lik ely to be blocke d if the Spann ing 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 att ached to
faster media, and higher values assigned to ports with slower media. (P ath cost
takes precedence over port priority.) Note that when the Path Cost Method is set
to short (page 3-63), the maximum pa th cost i s 65,535.
By default, the system automatically detects the speed and du plex 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.
Table 10-4 Recommended STA Path Cost Range
Port Type
Gigabit Ethernet
10G Ethernet
Short Path Cost
*
(IEEE 802.1D-1998)
2,000-65,535
200-20,000
Long Path Cost
*
(802.1D-2004)
2,000-200,000
200-20,000
* Use the STA Configuration screen (page 10-6) to set the path cost method.
Table 10-5 Def aul t STA Pa th Costs
Port Type
Gigabit Ethernet
10G Ethernet
Short Path Cost* Long Path Cost*
(IEEE 802.1D-1998) (802.1D-2004)
10,000 10,000
1,000 1,000
* Use the STA Configuration screen (page 10-6) to set the path cost method.
• Admin Link Ty pe – The link type a ttache d to th is inte rface.
• Point-to-Point – A connectio n to exactl y one other brid ge.
• Shared – A connection to two or more bri dges.
• Auto – The switch automatically deter mines if the interfac e is attach ed to a
point-to-point link or to shared media. (This is the default setting.)
•
Admin Edge Port
(Fast Forwarding) – You can enable this option if an interface is
attached to a LAN segment that is at the e nd of a b ridged L AN or to an end no de.
Since end nodes
cannot
cause forwarding loops, they can pass directly through to
the spanning tree forwarding state. Specifying Edge Ports provides quicker
convergence for devices such as workstations o r servers, retains th e curr ent
10-14
Spanning Tree Algorithm
10