Metro Ethernet technologies involve the use of carrier Ethernet in Metropolitan Area Networks (MANs). Metro Ethernet can connect company LANs and individual end-users to a WAN or to the Internet. Companies often use Metro Ethernet to connect branch offices to an intranet.
A typical Metro Ethernet deployment uses a star or a mesh topology with interconnected network nodes using copper or fibre optic cables. Using the standard and widely deployed Ethernet technology in Metro Ethernet deployments offers a number of advantages, as opposed to using SONET/SDH or MPLS technologies:
- Less expensive
- Easier to implement
- Easier to manage
- Easy to connect customer equipment because it uses the standard Ethernet approach
A typical MAN can be structured under the access/aggregation/core standard design (a Cisco design model), as follows:
- Access Layer – usually at the customer’s premises. This may include an office router or residential gateway
- Aggregation Layer – usually comprises microwave, DSL technologies, or Point-to-Point Ethernet links.
- Core Layer – may use MPLS to interconnect different MANs
Customer traffic separation is usually ensured in a MAN by using Ethernet VLAN tags that allow the differentiation of packets.