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A review of frame relay and leased lines in computer networking

History[ edit ] Leased lines services or private line services became digital in the 1970s with the conversion of the Bell backbone network from analog to digital circuits.

With the extension of digital services in the 1980s, leased lines were used to connect customer premises to frame relay or ATM networks. Access data rates increased from the original T1 option up to T3 circuits.

In the 1990s, with the advances of the Internet, leased lines were also used to connect customer premises to ISP point of presence whilst the following decade saw a convergence of the aforementioned services frame relay, ATM, Internet for businesses with the MPLS integrated offerings.

Applications[ edit ] Leased lines are used to build up private networks, private telephone networks by interconnecting PBXs or access the internet or a partner network extranet.

  • Figure 2-20 displays a sample Ethernet WAN topology;
  • There are two types of ISDN interfaces;
  • For small businesses, these relatively low-speed dialup connections are adequate for the exchange of sales figures, prices, routine reports, and email;
  • Leased lines are available in different capacities and are generally priced based on the bandwidth required and the distance between the two connected points.

Here is a review of the leased-line applications in network designs over time: Site to site data connectivity[ edit ] Terminating a leased line with two routers can extend network capabilities across sites. 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 especially when the savings on the telephone bill exceeded the fixed cost of the leased line.

Site to network connectivity[ edit ] As demand grew on data network telcos started to build more advanced networks using packet switching on top of their infrastructure. Leased lines were used to connect the customer site to the telco network access point.

International private leased circuit[ edit ] An international private leased circuit IPLC functions as a point-to-point private line.

Then came the Internet in the mid-1990s and since then the most common application for leased line is to connect a customer to its ISP point of presence.

The NTE will terminate the circuit and provide the requested presentation most frequently X.

Leased line

In the United States[ edit ] In the U. Higher-speed leased lines are usually presented using FT1 Fractional T1: In Hong Kong[ edit ] In Hong Kongleased lines are usually available at speeds of 64k, 128k, 256k, 512k, T1 channelized or not or E1 less common.

Fibre circuits are slowly replacing the traditional circuits and are available at nearly any bandwidth. Customers would have to manage their own network termination equipment, namely the channel service unit and data service unit.

  • What is the geographic scope?
  • The topology in Figure 1-32 displays a sample cable WAN connection;
  • What are the security requirements data integrity, confidentiality, and security?
  • DWDM multiplies the amount of bandwidth that a single strand of fiber can support, as illustrated in Figure 1-19.

Local telephone companies also may provide CDA Circuito Diretto Analogicothat are plain copper dry pair between two buildings, without any line termination: For many purposes, leased lines are gradually being replaced by DSL and metro Ethernet. Some internet service providers have therefore developed alternative products that aim to deliver leased-line type services carrier Ethernet -based, zero contention, guaranteed availabilitywith more moderate bandwidth, over the standard UK national broadband network.

While a leased line is full-duplexmost leased line alternatives provide only half-duplex or in many cases asymmetrical service.