Specifications

Switching 8-39
Software Release 2.7.3
C613-03098-00 REV A
Setting the path cost to a larger value on a particular port is likely to reduce the
traffic over the LAN connected to it. This may be appropriate if the LAN has a
lower bandwidth, or if there are reasons for limiting the traffic across it. To
modify the STP port path cost, use the command:
set stp={stp-name|all} port={port-list|all}
pathcost=1..200000000
If the path cost of a port has been explicitly set to a particular value, it can be
returned to its self-adjusting default path cost and priority, using the
command:
set stp={stp-name|all} port={port-list|all} default
When an STP is enabled in a looped or meshed network, it disables and
enables particular ports belonging to it dynamically, to eliminate redundant
links. All ports in a VLAN belong to the same STP, and their participation in
STP configuration, and hence the possibility of them being elected to the STP’s
active topology is enabled by default. To enable or disable particular ports, use
the commands:
enable stp port={port-list|all}
disable stp port={port-list|all}
STP treats a trunk group configured on both ends of a link as a single path.
To display STP port information, use the command:
show stp[={stp-name|all}] port={port-list|all}
The spanning tree algorithm can be recalculated at any time, and all timers and
counters be initialised, using the command:
reset stp={stp-name|all}
To display STP counters, use the command:
show stp={stp-name|all} counter
Enabling one or more STP debugging modes for a period of time displays
information for STP troubleshooting (Table 8-11) to the port on which the
switch received the command, or to the console.
Table 8-10: Path cost values and port speed for rapid mode
Port Speed Default PATHCOST Recommended PATHCOST range
Less than 100 Kb/s 200,000,000 20,000,000-200,000,000
1Mbps 20,000,000 2,000,000-20,000,000
10Mbps 2,000,000 200,000-2,000,000
100 Mbps 200,000 20,000-200,000
1 Gbps 20,000 2,000-20,000
10 Gbps 2,000 200-2,000
100 Gbps 200 20-200
1Tbps 20 2-200
10 Tbps 2 2-20