This paper will define and compare two classes of access architectures that will emerge this decade for Passive Optical Network (PON). These two classes of access architecture may be referred to as centralized access architecture (CAA) and distributed access architecture (DAA) for PON. The CAA and DAA analysis is well underway for DOCSIS, but 10G EPON may be architected in a similar manner, in terms of splitting the PON access system components between the facility and a remote location, or placing all of the network device functions in a remote location. The DOCSIS use of distributed access architecture can place the MAC and PHY or just the PHY layer in the remote device, such as a node, cabinet, or multiple dwelling unit (MDU) location. The DAA for PON places both the MAC and PHY layers in the remote device. The DAA for PON defines how much of the upper layer functions are placed in the remote device and how much if any of the PON systems remain in the provider facility. The optical line terminal (OLT) has evolved from a simple layer 2 device into some systems supporting higher layer networking functions, including advanced layer 2, layer 3 routing, and Multiprotocol Label Switching (MPLS). In addition, the cable industry defined a software mediation layer subsystem for Ethernet PON (EPON) and 10G EPON that enabled them to leverage their existing provisioning, network management, and network accounting systems used for their DOCSIS network to be used for EPON, this effort was the basis of CableLabs DOCSIS Provisioning of EPON (DPoE) standards. The DPoE specifications defined advanced routing, switching, optical line terminal (OLT), and mediation layer subsystems to be part of a DPoE system. The DPoE system refers to the set of subsystems within the hub site that provides the functions necessary to meet the DPoE specification requirements [CableLabs]. This paper defines and examines next generation DPoE systems, which functions may not reside completely at a hub site, but rather can be in the cloud, hub site, and/or node locations. The next generation DPoE Systems will include additional features to facility based CAA DPoE systems and DAA DPoE systems. The use of centralized access architecture (CAA) retains the MAC and PHY layer functions of the OLT subsystem in the headend or hub location. This paper will examine several current centralized access architectures for OLT subsystems. This paper will also propose the adoption of multiple wavelength technologies for 10G EPON DPoE systems. Three types of CAA DPoE systems will be examined in this paper. The distributed access architecture (DAA) for PON began in the early 2000's with the placement of the entire OLT functions in a node or cabinet, this was referred to as remote OLT or OLT in the node. At the core of the next generation DAA DPoE systems there are three different distributed access architecture types that will be defined and evaluated in this paper. These define the functions that will be placed in the node or cabinet locations as well as those that may be placed at the facility; the facility may be a hub site or the cloud like a regional data center (RDC).
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