All kinds of multi-site enterprises need connectivity to enable their staff and back-office systems to communicate. In addition to using public services such as the PSTN/ISDN, the Internet and mobile communications, many enterprises have traditionally also used private services, supplied by a network operator.

Analogue line services are being withdrawn from new supply, but the well-established digital services still being offered include serial (TDM) circuits (e.g. E1 or T1), Frame Relay or ATM. However, it is generally expected that services based on Ethernet and IP technologies will replace the older alternatives because of simpler interfacing to enterprise equipment and potential for lower price per bit, and increased scalability. For an enterprise to make such a change they must be motivated by factors such as changes in their connectivity requirements, service cost satisfaction or indeed: service performance,  which could be associated with an increase in bandwidth needs.

This solution is focused on private, inter-site services delivered using Ethernet and providing Ethernet or IP connectivity. The connectivity can be point-to-point or multipoint.

Network operators can choose from several methods of carrying Ethernet and IP enterprise services in their network, such as IP, MPLS (and MPLS-TP), Carrier Ethernet, NG-SDH and WDM, and various choices of access media: copper, fibre (pt-pt or PON) or microwave radio. The best choices for each operator will depend on such details as:

• Other services that are to be delivered over a converged network – where the operator will optimize the network for the overall service requirements
• Existing access, aggregation and backbone technologies, or the operator plans to enhance these for packet services
• The location of the enterprise sites to be connected and any existing access infrastructure available for these. Where no owned infrastructure exists, methods can be used to deliver service over access services leased from other operators (such as E1 or T1 circuits)