Metro Ethernet - Metropolitan Area Network (MAN) Topology

Metropolitan Area Network (MAN) Topology

Familiar network domains are likely to exist regardless of the transport technology chosen to implement Metropolitan area networks: Access, aggregation/distribution, and core.

• Access devices normally exist at a customer's premises, unit, or wireless base station. This is the network that connects customer equipment, and may include ONT and/or Residential gateway, or office router.
• Aggregation occurs on a distribution network such as an ODN segment. Often Passive Optical Network, microwave or Digital Subscriber Line technologies are employed, but some using point-to-point Ethernet over "home-run" direct fibre. This part of the network includes nodes such as Multi Tenanted Unit switches, Optical line terminals in an outside plant or central office cabinet, Ethernet in the First Mile equipment, or provider bridges.
• A MAN may include the transport technologies MPLS, PBB-TE and T-MPLS, each with its own resiliency and management solutions.
• A core network often uses IP-MPLS to connect different MANs together.

Much of the functionality of Ethernet MANs such as virtual private lines or virtual private networks is implemented by the use of Ethernet VLAN tags that allow differentiation of each part of the network. Logical differentiation of the physical network helps to identify the rights that the traffic has and to ease the management of hosts' access rights with respect to other users and networks.