Site to site data connectivity

Terminating a leased line with two routers can extend network capabilities across sites. Leased lines were first used in the 1970s by enterprise with proprietary protocols such as IBM System Network Architecture and Digital Equipment DECnet, and with TCP/IP in University and Research networks before the Internet became widely available. Note that other Layer 3 protocols were used such as Novell IPX on enterprise networks until TCP/IP became ubiquitous in the 2000s.

Today, point to point data circuits are typically provisioned as either TDM, Ethernet, or Layer 3 MPLS.Terminating a leased line with two PBX allowed customers to by-pass PSTN for inter-site telephony. This allowed the customers to manage their own dial plan (and to use short extensions for internal telephone number) as well as to make significant savings if enough voice traffic was carried across the line (specially when the savings on the telephone bill exceeded the fixed cost of the leased line).

As demand grew on data network telcos started to build more advanced network using packet switching on top of their infrastructure. Thus number of telecommunication companies added ATM, Frame-relay or ISDN offerings to their services portfolio. Leased lines were used to connect the customer site to the telco network access point.

December 26, 2011

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