This page details the local and distribution elements of the FTTP network in addition to the wireless, satellite and backhaul components of the NBN.
Network Termination Unit (NTU)
The NTU will be available in a range of indoor and outdoor models, however the default deployment option is internal. The residential NTU is PON based and will be able to provide 100Mbps CIR services and burst upto 1Gbps PIR. This NTU will be able to be installed in MDUs when fibre has been installed to each user premise. The residential version features four electrical 10/100/1000BaseTX ethernet ports and one or two analogue telephony ports1. The business versions are PON and PtoP based and feature four electrical or optical ethernet ports for the provision of multiple 1Gbps services using redundant geographically diverse fibre pathways for mission critical applications as required2. Information on EUP wiring is available here.
Figure 1 Alcatel Lucent indoor residential NTU3
Property Connection Point (PCP)
The NTU transmits optic fibre signals to the Local Distribution network via the Property Connection Point (PCP) junction box. This box only contains a small loop of fibre optic cable and does not require a power supply. Overhead deployments feature a fibre optic cable to the closest street pole containing a Network Access Point (NAP) terminal. Underground NBN deployments feature a fibre optic cable connecting to one of the closest P1/P2/P4/P54 pits to the premises.
Figure 2 Property Connection Point in overhead NBN deployment
The local network features 3 dedicated, separate fibre optic cables that run between the closest NAP to an End User Premises (EUP) and a Fibre Distribution Hub (FDH)5. The closest NAP to your premise is usually a P1/P2/P4/P5 pit if the cabling is underground or the closest street pole in the case of an overhead deployment. Each FDH is designed to support a maximum of 288 premises.
Figure 3 (Top Left) 12-port FlexNAP terminal. (Top Right) 4-port
FlexNap terminal in pit. (Bottom Left) Fibre Distribution Hub (FDH). (Bottom Right) Pit beneath FDH, showing waterproof splicing tray and fibre terminators6
The presence of 3 fibres between the FDHs and EUPs enables multiple GPON networks to be deployed simultaneously. For example, as of late 2010, NBNCo has chosen to rollout 2.5Gbps GPON systems (2.5GPON) in optical Network Terminals (ONTs) deployed in EUPs that feature single wavelength data transmission protocols split between a maximum of 32 users. Over the 40-50 year lifetime of the fibre cabling used in the NBN system, new technologies such as 10-40Gbps GPON systems (10GPON, 40GPON) may become prevalent. One of the spare cables between the FDH and the end user premises is designed to utilise such new equipment cost effectively since the the capability exists to install the 10GPON system to operate simultaneously with the 2.5GPON system. The 2.5GPON and 10GPON systems use separate fibres. Upgrades can occur to single customers at one time, meaning that it is not necessary to upgrade all the end user equipment on a particular 32-port customer fanout. This means that network upgrades can be performed in a quick, easy and efficient manner without the need to install extra fibre cabling.
Another advantage of the multi-shared GPON architectural topology inherit in the NBN system is that the presence of spare cabling between the FDH and the FAN enables an estimated 6% of users across the national footprint to upgrade to a direct PtoP link.
The distribution network connects the FDHs to the Fibre Access Nodes is a double-lasoo configuration. A single NBN fibre optic cable is typically 21mm thick7 and contains 312 cores with separate tubes for distribution, trunk, GPON and PtoP fibres. This distribution network is geographically redundant and enables business subscribers of NBNCo to simultaneously utilise signals fed from two fibres using a GPON/PtoP link for improved resiliency in mission critical applications.
Figure 3 Geographically redundant FSAM fibre distribution network8
Fibre Access Node (FAN)
Each FAN is designed to serve approximately 76,800 individual premises and switch 152PB per month by directly connecting to the 384 FDHs across 24 Fibre Serving Area Modules (FSAMs). Fibres from the FDHs will be terminated in the FAN using high density fibre distribution management frames9 before being used as input to 2.5GPON linecards, 10GPON linecards, PtoP linecards, Ethernet Aggregation Switches and medium-long haul fibre optic transmission equipment.
The CSIRO fixed wireless systems reportedly offers speeds of up to 12Mbps up and down (per television channel), shared between up to 1000 homes in a roughly 15 to 20 kilometre radius of a broadcast tower10.
The full tender document for NBNCo’s Long Term Satellite Solution will be released sometime next month (November)11
NBNCo will implement a backhaul network between 14 aggregation PoIs, 195 connecting serving area PoIs and 714 FANs throughout the country12.
- Page 63, NBN Technical Specifications Fibre Access Services, 2010 [↩]
- Quigley: NBN Co to deliver 1Gbps, ZDNet, 2010 [↩]
- Coming to a wall near you: Meet the NBN ONT, Computerworld, 2010 [↩]
- BVCI Telecommunications Pit Product Catalog, 2008/9 [↩]
- Corning, OptiTect® Local Convergence Cabinet, Gen III Series [↩]
- Page 12, NBN Network and Operations Information Session [↩]
- Corning, ALTOS® RD All-Dielectric Cables, 300-432 Fibers [↩]
- Page 15, NBN Network and Operations Information Session [↩]
- Corning, Enhanced Management Frame (EMF) [↩]
- CSIRO to begin commercialising Ngara broadband over TV spectrum technology, CIO, 2010 [↩]
- NBN business plan to board this week: Quigley, iTWire, 2010 [↩]
- Page 16, NBN Point of Interconnects [↩]