Open for all: designing successful open access ultra-fast broadband networks

Interested in this topic? Contact our expert Nicolas Tassitani @

October 13, 2009

…the requirement to provide the open access layer 1 service will preclude some network design options

A common theme associated with state-funded plans for national broadband infrastructure around the world is that of providing “open access”. This ensures that customers have as wide a choice as possible of services and service providers on the new network. Governments and regulators have taken a range of open access approaches, from mandating full access for service providers to physical cables (layer 1) through to access network operators being required to supply managed data services at layer 2 and above.

Open access also features strongly in the New Zealand Government’s initiative to fund Ultra-Fast Broadband and the main requirements are detailed in the Invitation to Participate, released in October 2009:

  • non-discrimination and equivalent services provided to all access seekers
  • availability of co-location services at central office sites
  • provision of a “Specified Layer 1” service which is effectively a dark fibre from the customer location to the central office site.

Providing for open access requirements in their network designs is likely to be a key consideration for parties planning investment in this initiative. In particular, the requirement to provide the open access layer 1 service will preclude some network design options that may otherwise have been proposed.

Fibre to the home (FTTH) network designs typically involve some degree of shared fibre infrastructure between the customer and central office, as opposed to dedicating one fibre to each customer. This is true for both Passive Optical Networks (PON) and Active Ethernet systems which deploy either passive splitters or active multiplexors to share fibre capacity between the central office and remote nodes closer to the customer. Remote nodes and shared backhaul have long been seen as key components in the design philosophy of Next Generation Networks (NGNs), which seek to:

  • reduce the amount of access and core network equipment dedicated to individual customers or services
  • provide all services over a single access line
  • ultimately reduce the number of central office sites required to operate the network.

The implications of providing for New Zealand’s specified layer 1 service will become clear as parties make their proposals, but they will require a modified NGN access approach which may involve:

  • limitations on the practical deployment of PON networks, particularly de-centralised or pole mounted splitters which provide flexibility in networks such as Verizon’s FTTH installation
  • limitations on the ability to use aerial fibre infrastructure due to the need to provide very high fibre count cables which cannot be pole mounted
  • the need to provide significant numbers of spare fibres between central offices and remote nodes that contain splitter or multiplex equipment
  • the need to retain or build new central office sites with sufficient capacity to house a range of access seeker equipment and potentially to terminate a large number of individual customer fibres.

We expect that uptake of the specified layer 1 fibre service will be similar to New Zealand’s experience with copper local loop unbundling, where the unbundled exchanges correspond to major population centres and only the larger or most innovative alternative service providers have had sufficient market scale to make use of the service. Smaller and start-up players are likely to be principally dependent on open access layer 2 or “bitstream” services, probably in the form of cost-effective Ethernet interfaces which can provide for a range of service speeds and qualities. Although the Government has identified the potential need for layer 2 services, they are not mandatory and will not be directly funded.

Overall, we believe that New Zealand’s ultra-fast broadband open access requirements will lead to a future-proof network. In addition to the layer 1 access service, we expect that there will be significant demand for open access layer 2 services and that specifying and standardising these will require centralised coordination. For the network designers and financiers, there will be a range of challenging architecture, capacity and cost trade-offs, with specific regional variation and no “one size fits all” solution.