3Com 4007R Implementation Guide - Page 189

Address Aging 189 Address Aging This section explains how address aging works and identifies the slight differences in options and operation between Layer 2 Switching Modules and Multilayer Switching Modules. Address aging only applies to dynamic addresses. (Static addresses are never aged from the address table and cannot be learned on other ports until they have been manually removed.) Address Table Dependencies The amount of time that dynamic addresses remain in a module's address table depends on these factors: s The aging interval value that you configure (bridge agingTime) s The option that you select for the bridge STP state: s For Multilayer Switching Modules, choose enabled or disabled s For Layer 2 Switching Modules, choose enabled, disabled, or agingOnly s These options are explained later in this section. s The module's detection of link state changes on ports; shorter aging intervals may be applied for a certain period of time, depending on the STP state that you have selected. s The value that you configure for STP forward delay on the module or that is assigned to the module by the STP root bridge. The value used depends on the STP state that you have selected. s Other non-aging factors, such as STP topology changes and power cycles. See "Important Considerations" in the previous section "MAC Address Table Design" for more information. On Layer 2 Switching Modules, if you do not want to enable STP but you do want accelerated aging to occur when ports go down, select the agingOnly option from the bridge spanningTree stpState command. You may also want to modify the two STP parameters that the agingOnly function uses. None of these actions will enable STP itself.