In access multiplexers (1) comprising network interfaces (22) for interfacing network links (12) with network units (2) and comprising customer interfaces (23-25) for interfacing customer links (13-15) with customer units (3-5) and comprising coupling means (31) for coupling the interfaces (22-25), allocating means (32) are introduced for allocating Medium Access Control addresses to Internet Protocol sessions and controlling means (30) are introduced for controlling the access multiplexers (1) in dependence of allocations, for increasing efficiencies. The customer units (3-5) form part of one subnet (10). The network links (12) comprise Ethernet connections defined by Virtual Local Area Network tags per subnet (10). The allocating means (32) comprise relating means (33) for relating combinations of Virtual Local Area Network tags and Medium Access Control addresses to session identifications of the Internet Protocol sessions, with the allocations comprising relationships. The customer links (13-15) comprise Asynchronous Transfer Mode connections or Ethernet connections.