The communications industry is on the cusp of a revolution characterized by three driving forces that will forever change the communications landscape. First, deregulation has opened the local loop to competition, launching a whole new class of carriers that are spending billions to build out their networks and develop innovative new services. Second, the rapid decline in the cost of fiber optics and Ethernet equipment has made them an attractive option for access loop deployment. Third, the Internet has precipitated robust demand for broadband services, leading to an explosive growth in Internet Protocol (IP) data traffic while, at the same time, putting enormous pressure on carriers to upgrade their existing networks.
These drivers are, in turn, promoting several key market trends. In particular, the deployment of fiber optics is extending from the telecommunications backbone to Wide-Area Network(s) (WAN) and Metropolitan-Area Network(s) (MAN) and the local-loop. Concurrently, Ethernet is expanding its pervasiveness from Local-Area Network(s) to the MAN and the WAN as an uncontested standard.
The confluence of these factors is leading to a fundamental paradigm shift in the communications industry, a shift that will ultimately lead to widespread adoption of a new optical IP Ethernet architecture that combines the best of fiber optic and Ethernet technologies. This architecture is poised to become the dominant means of delivering bundled data, video, and voice services on a single platform.
Passive Optical Networks (PONs) address the “last mile” of communications infrastructure between a Service Provider's Central Office (CO), Head End (HE), or Point of Presence (POP) and business or residential customer locations. Also known as the “access network” or “local loop”, this last mile consists predominantly—in residential areas—of copper telephone wires or coaxial cable television (CATV) cables. In metropolitan areas—where there is a high concentration of business customers—the access network often includes high-capacity synchronous optical network (SONET) rings, optical T3 lines, and copper-based T1 lines.
Historically, only large enterprises can afford to pay the substantial costs associated with leasing T3 (45 Mbps) or optical carrier (OC)-3 (155Mbps) connections. And while digital subscriber line (DSL) and coaxial cable television (CATV) technologies offer a more affordable interim solution for data, they are infirmed by their relatively limited bandwidth and reliability.
Yet even as access network improvements have remained at a relative bandwidth standstill, bandwidth has been increasing dramatically on long haul networks through the use of wavelength division multiplexing (WDM) and other technologies. Additionally, WDM technologies have penetrated metropolitan-area networks, thereby boosting their capacities dramatically. At the same time, enterprise local-area networks have moved from 10 Mbps to 100 Mbps, and soon many will utilize gigabit (1000 Mbps) Ethernet technologies. The end result is a gulf between the capacity of metro networks on one side, and end-user needs and networks on the other, with a last-mile “bottleneck” in between. Passive optical networks—and in particular Ethernet Passive Optical Networks—promise to break this last-mile bottleneck.
The economics of PONs are compelling. Optical fiber is the most effective medium for transporting data, video, and voice traffic, and it offers a virtual unlimited bandwidth. But the cost of deploying fiber in a “point-to-point” arrangement from every customer location to a CO, installing active components at each endpoint, and managing the fiber connections within the CO is prohibitive. PONs address these shortcomings of point-to-point fiber solutions by using a point-to-multipoint topology instead of point-to-point; eliminating active electronic components such as regenerators, amplifiers, and lasers from the outside plant; and by reducing the number of lasers needed at the CO.
Unlike point-to-point fiber-optic technology, which is typically optimized for metro and long haul applications, PONs are designed to address the demands of the access network. And because they are simpler, more efficient, and less costly than alternative access solutions, PONS finally make it cost effective for service providers to extend optical fiber into the last mile.
Accordingly, PONs are being widely recognized as the access technology of choice for next-generation, high speed, low cost access network architectures. PONs exhibit a shared, single fiber, point-to-multipoint passive optical topology while employing gigabit Ethernet protocol(s) to deliver up to 1 Gbps of packetized services that are well suited to carry voice, video and data traffic between a customer premises and a CO. Adding to its attractiveness, PONs have been recently ratified by the Institute of Electrical and Electronics Engineers (IEEE) Ethernet-in-the-First Mile (EFM) task force in the IEEE 802.3ah specification.
With reference to FIG. 1, there is shown a typical PON as part of overall network architecture 100. In particular, an EPON 110 is shown implemented as a “tree” topology between a service provider's CO 120 and customer premises 130[1] . . . 130[N], where a single trunk or “feeder” fiber 160 is split into a number of “distribution” fibers 170[1] . . . 170[N] through the effect of 1×N passive optical splitters/combiner 180.
As can be further observed with reference to this FIG. 1, the trunk fiber 160 is terminated at the CO 120 at Optical Line Terminator (OLT) device 190 and split into the number of distribution fibers 170[1] . . . 170[N] which are each either further split or terminated at an Optical Network Unit (ONU) 150[1] . . . 150[N] located at a respective customer premises 130[1] . . . 130[N].
Due to the directional properties of the optical splitter/combiner 180, the OLT 190 is able to broadcast data to all ONUs in the downstream direction. In the upstream direction, however, ONUs cannot communicate directly with one another. Instead, each ONU is able to send data only to the OLT. Thus, in the downstream direction a PON may be viewed as a point-to-multipoint network and in the upstream direction, a PON may be viewed as a multipoint-to-point network.
As can be readily appreciated, in a large passive optical network, there exist a very large number of PON OLT devices. Managing this plurality of devices is a job that has historically involved a tedious, manual provisioning of static configurations. As a result, configurations are oftentimes replete with errors that are not easy to detect.