The Principle and Configuration of a Leased Line (LL) network

A Leased Line (LL) service is a point-to-point data communication for communicating any data between two sites. The channel bandwidth reserved for each customer isn’t shared with other customers, and the data speed of LL depends on customer requirements.

A Leased line network composes of a Data Terminal Equipment (DTE), a Data Communication Equipment (DCE), and work stations (a PC, a server, or other LAN equipment) at each customer site. A DCE generates the clock signal for synchronizing between a DCE and a DTE.

In the provider site, there are LL nodes used for transmitting the data signal from the source to the destination of customer sites.

Mainstreet is an example of LL networks ; it is one of Alcatel’s network equipment. Mainstreet DCE is called Data Terminal Unit (DTU), and there are various types of mainstreet nodes in a provider network. A DTE is customer’s router connecting to a DTU with a serial port. The mainstreet configuration is displayed below :

LAN equipment or PCs (LAN port) <--> (LAN port) Router (Serial port) <--> (V.35 port) DTU (RJ-11 port) <--> (Line port) Mainstreet node (E1 port) <--> To the other site.

A customer’s router can directly connect to a mainstreet node without a DTU, if a mainstreet node use a V.35 card.