Patent ID: 8031630

Claim:
A method for communication between two or more customer virtual local area network (LAN) segments through a provider network, with each customer virtual LAN segment including a customer edge bridge, and where the provider network has one or more provider edge bridges coupled to the customer edge bridges, comprising the steps of: in at least one of the provider edge bridges coupled to a customer virtual LAN segment: receiving a topology change notification (TCN) from a customer network in response to a topology change in one or more of the customer virtual LAN segments; in response to receiving the TCN from the customer network, monitoring end host media access control (MAC) addresses in data units received from the customer network for a predetermined time period to determine whether the topology change in the one or more of the customer virtual LAN segments affects paths of data units through the provider network; determining that the topology change in the one or more of the customer virtual LAN segments does not affect paths of data units through the provider network wherein the determining includes: determining that less than a predetermined number of new end host MAC addresses of data units received from the customer network in the predetermined time period are not found in a MAC address memory file, wherein the MAC address memory file associates end host MAC addresses with ports of the provider edge bridge; and determining no contradictions occur in the predetermined time period between an end host MAC address of a data unit received from the customer network and the MAC address memory file; and in response to determining the topology change in the one or more of the customer virtual LAN segments does not affect paths of data units through the provider network upon receiving the TCN from the customer network, storing the new end host MAC addresses of data units received from the customer network in the predetermined time period in the MAC address memory file without flushing the MAC address memory file; and in response to determining the topology change in the one or more of the customer virtual LAN segments affects paths of data units through the provider network upon receiving the TCN from the customer network, flushing the MAC address memory file.