Like a Layer 2 switch, learned MACs within a VPLS instance can be aged out if no packets are sourced from the MAC address for a specified period of time (the aging time). In each VPLS service instance, there are independent aging timers for locally learned MAC and remotely learned MAC entries in the FDB. A local MAC address is a MAC address associated with a SAP because it ingressed on a SAP. A remote MAC address is a MAC address received by an SDP from another router for the VPLS instance. The local-age timer for the VPLS instance specifies the aging time for locally learned MAC addresses, and the remote-age timer specifies the aging time for remotely learned MAC addresses.
In general, the remote-age timer is set to a longer period than the local-age timer to reduce the amount of flooding required for unknown destination MAC addresses. The aging mechanism is considered a low priority process. In most situations, the aging out of MAC addresses happens within tens of seconds beyond the age time. However, it, can take up to two times their respective age timer to be aged out.