Communications service providers are continuously being pressed by users to increase network capacity. Commonplace services now include Voice over Internet Protocol (VoIP), high-bandwidth on-demand audio and video, and high-bandwidth data connections to private or public networks, such as the Internet. The development of optical fiber communication technologies has enabled exponential growth in the capacity of backbone networks, with Passive Optical Networks (PONs) and specifically Gigabit Passive Optical Networks (GPONs) proposed as a flexible broadband infrastructure for delivering cost effective and environmentally friendly/energy efficient telecommunications services including voice, video and data to homes and businesses.
FIG. 1 shows a prior art PON architecture 100 of a PON providing access to subscribers/customers as a loop technology, as is known by those skilled in the art. In this network architecture, an Optical Line Terminal (PON OLT) 102 optical transceiver at a service provider's central office (CO) 104, connected via Optical Fiber 106 to a Remote Node 108 containing a passive optical splitter 110 located in the vicinity (neighborhood) of multiple customers. The fiber 112 may then be connected to an Optical Network Unit (ONU) 114. ONUs interface optical signals to electrical signals, such as an Unshielded Twisted Pair (UTP) in a telecommunications network, an example of which is a Digital Subscriber Line (DSL) including its variants, or a coaxial cable in a cable network. As such, the electrical signals can then be sent to the appropriate Customer Premises (CP) 116, 118. Alternatively, optical signals can be sent directly from the Remote Node 108 containing a passive optical splitter 110 via optical fiber 120 to a Customer Premises/Optical Network Unit (CP/ONU) 122. The ONU in this context is an addressable device that recognizes and accepts only downstream data addressed specifically to it. Exemplary CPs as shown in FIG. 1 are depicted as home/individual users, however similar architectures apply to small business and larger enterprise users as their service agreements and/or network designs permit.
FIG. 2 shows a prior art PON architecture 200 providing trunking to another type of network element, such as a Digital Subscriber Line Access Multiplexer (DSLAM). In this network architecture, as with the network of FIG. 1, an Optical Line Terminal (PON OLT) 202 optical transceiver at a service provider's central office (CO) 204, is connected via Optical Fiber 206 to a Remote Node 208 containing a passive optical splitter 210 located in the vicinity (neighborhood) of multiple customers. The fiber 212 may then be connected to an ONU 214. At this point the network architectures differ from that of FIG. 1, in that the fiber 213 connects via a Gigabit Interface Converter (GBIC) to DSLAM 215 which provides optical/electrical signal interface and multiplexing functionality, and makes the connection to the appropriate DSL modem at Customer Premises (CP) 216, 218 and 222.
The PON architectures described above eliminate the requirement for optical-to-electrical-to-optical (OEO) conversion at each node of the fiber optic network by employing passive optical components such as beam splitters and filters at network nodes instead of active optical components. By eliminating the active optical components associated with an active optical network, less hardware/software is required, which in turn reduces active network management by a network administrator, and reduces energy consumption of the associated components. PON architecture, therefore, is cost effective and environmentally friendly/energy efficient solution when compared to active fiber optic networks.
The term Gigabit Interface Converter (GBIC) refers to both a standard for transceivers and to a device for interfacing network devices to a fiber optic based transmission system such as fiber channel or other high speed non-optical based system(s) and to a Gigabit Ethernet. The GBIC is just one example of the pluggable transceivers defined by a growing number of form factor and interfacing standards. Other standards in use today include the Small Form-Factor Pluggable (SFP) specification, the 10 Gigabit Small Form Factor Pluggable (XFP) specification, the XFI 10 gigabit per second chip-to-chip electrical interface specification (XFI) and the XENPAK Multisource Agreement (MSA),
The GBIC device converts serial electrical signals to serial optical signals and visa versa. GBIC modules are generally hot swappable; that is, they can be inserted and removed from a host or switch chassis without powering off the receiving socket, and contain device identification and configuration information that a host or switch can use to determine the device's capability. As a plug-in module, the GBIC includes physical pins or card edge contacts that form a single pluggable interface that provides both signal connections and power connections between the GBIC and the host. The GBIC enables network designers and administrators to cost effectively deploy and upgrade network capability as justified by increased network traffic, capital budgets and as technology advances are made.
The term “pluggable transceiver,” as used in this specification, refers to a pluggable device that connects a host device with a communications medium such as short-distance fiber, long-distance fiber or copper. From the host device perspective, the connection conforms to a communications standard such as Gigabit Ethernet, SONET or Fibre Channel. A pluggable transceiver differs from a router line card or router blade in several ways, one being that the pluggable transceiver is intended to plug in to a variety of devices and cards from a variety of suppliers; whereas the line card is designed for a particular router and supports a limited number of higher-layer protocols, like Frame Relay, ATM, Ethernet, or SONET. Moreover, the router line card has firmware and management capabilities that must be coordinated with the router firmware, whereas the pluggable transceiver is largely independent of the router firmware. The term “independent,” as used here, means that software/firmware in the pluggable transceiver performs the same tasks in the same way regardless of what software/firmware is running in the router or other network equipment, and need not be changed according to the software/firmware running in the router or other network equipment.
The appeal of the GBIC standard in networking equipment, as opposed to fixed physical interface configurations, is its flexibility. Where multiple different optical technologies are in use, a network designer or administrator can deploy GBICs as needed, not in advance, in the specific type needed for each link. The term GBIC will be used in this application to broadly describe the current definition of the standard/device, and include variations such as the mini-GBIC, SFP, XFI/XFP and others.
All networks, including PONs comprising network devices such as ONUs, require a level of network monitoring and management to facilitate efficient, effective and reliable operation. A Network Management System (NMS) typically employs a combination of hardware and software to monitor and administer a network.