Netgear XCM8810 Chassis Hardware Installation Guide - Page 757

NETGEAR 8800 Chassis Switch CLI Manual auto cost port_list Specifies the switch to remove any user-defined port cost value(s) and use the appropriate default port cost value(s). Specifies a numerical port cost value. The range is 1 through 200,000,000. Specifies one or more ports or slots and ports. Default The switch automatically assigns a default path cost based on the speed of the port, as follows: • 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. Usage Guidelines If your STPD has the same name as another component, for example a VLAN, NETGEAR recommends 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 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. Chapter 17. STP Commands | 757