Patent ID: 7756146

Claim:
A MAC (media access control) frame transfer method for reducing a flooding in a backbone network with which a plurality of customer local area networks are connected via respective edge bridges which each comprise at least one customer port and at least one backbone port to realize a VLAN (virtual local area network), the method comprising the steps of: receiving a MAC frame from one of said customer local area networks via said at least one customer port of each edge bridge; identifying a service VLAN ID for said MAC frame from a customer port which received said MAC frame; obtaining a destination group ID for identifying a combination of a source of said MAC frame and at least one destination; on the basis of said obtained destination group ID, judging whether said at least one backbone port includes one which is to transfer said MAC frame; if said at least one backbone port includes at least one backbone port which is to transfer said MAC frame, forming a backbone MAC frame which includes said MAC frame and said service VLAN ID; setting said destination group ID in said backbone MAC frame; and transferring said backbone MAC frame with said destination group ID set to said at least one backbone port which is to transfer said MAC frame.