Specifies the path cost of the port in the specified STPD (Spanning Tree Domain).
| stpd_name | Specifies an STPD name on the switch. |
| auto | Specifies the switch to remove any user-defined port cost value(s) and use the appropriate default port cost value(s). |
| cost | Specifies a numerical port cost value. The range is 1 through 200,000,000. |
| port_list | Specifies one or more ports or slots and ports. |
10 Mbps port—the default cost is 2,000,000.
100 Mbps port—the default cost is 200,000.
1000 Mbps port—the default cost is 20,000.
10000 Mbps ports—the default cost is 2,000.
The default port cost for trunked ports is dynamically calculated based on the available bandwidth.
If your STPD has the same name as another component, for example a VLAN (Virtual LAN), we recommend that you specify the identifying keyword as well as the name. If your STPD has a name unique only to that STPD, the keyword stpd is optional.
You should not configure any STP (Spanning Tree Protocol) parameters unless you have considerable knowledge and experience with STP. The default STP parameters are adequate for most networks.
The 802.1D-2004 standard modified the default port path cost value to allow for higher link speeds. If you have a network with both 802.1D-2004 and 802.1D-1998 compliant bridges, a higher link speed can create a situation whereby an 802.1D-1998 compliant bridge could become the most favorable transit path and possibly cause the traffic to span more bridges. To prevent this situation, configure the port path cost to make links with the same speed use the same path host value. For example, if you have 100 Mbps links on all bridges, configure the port path cost for the 802.1D-2004 compliant bridges to 19 instead of using the default 200,000.
Note
You cannot configure the port path cost on 802.1D-1998 compliant bridges to 200,000 because the path cost range setting is 1 to 65,535.
The range for the cost parameter is 1 through 200,000,000. If you configure the port cost, a setting of 1 indicates the highest priority.
If you configured a port cost value and specify the auto option, the switch removes the user-defined port cost value and returns to the default, automatically assigned, port cost value.
The auto port cost of a trunk port is calculated based on number member ports in the trunk port. Link up and down of the member port does not affect the trunk port cost, thus it does not trigger topology change. Only adding or removing a member port to/from the trunk port causes auto trunk port cost to change. Also, by so configuring a static trunk port cost, the value is frozen regardless of the number of member ports in the trunk port.
If you have switches running ExtremeXOS 11.5 and earlier, the default costs are different than switches running ExtremeXOS 11.6 and later.
The range for the cost parameter is 1 through 65,535.
10 Mbps port—the default cost is 100.
100 Mbps port—the default cost is 19.
1000 Mbps port—the default cost is 4.
10000 Mbps ports—the default cost is 2.
The following command configures a cost of 100 to slot 2, ports 1 through 5 in STPD s0:
configure stpd s0 ports cost 100 2:1-2:5
This command was first available in ExtremeXOS 10.1.
The auto option was added in ExtremeXOS 11.0.
The default costs were updated based on support for the 802.1D-2004 standard in ExtremeXOS 11.6.
This command is available on the Summit X450-G2, X460-G2, X670-G2, X770, and ExtremeSwitching X440-G2, X590, X620, X690, X870 series switches.
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