NBN Co Network Design Rules

NBN Co Network Design Rules
3.6 Transport Domain
1.1.19. Dense Wavelength Division Multiplexing (DWDM)
The NBN Co Dense Wavelength Division Multiplexing (DWDM) fibre optic transport network is made
up of a number of DWDM Nodes (DNs) situated mainly at Point of Interconnect (POI) and Fibre
Access Node (FAN) sites, all interconnected by Optical Multiplex Section (OMS) links. A DN may also
be used within a link for amplification.
The DWDM network will predominantly provide physical connectivity and transit backhaul capacity
between POI and FAN sites. The network will also provide connectivity to centralised depots, data
centres and delivery points for the specific transport services that require them.
The following diagram shows the basic connectivity scenarios for the DWDM network. Each DN has a
metric called “degree of connectivity”, which is the number of fibre interfaces it has, and therefore
the number of other DNs it can connect to. The DN at POI 1, for instance, has a degree if two: it
connects to the DNs at two FAN sites. The DN at FAN 7 has a degree of one.
POI 1 POI 2
DN
DN
FAN 1 FAN 2
FAN 3
Depot/Data
Centre/Delivery
Point
DN
DN
DN
DN
DN
DN
Optical
Multiplex
Section
DN
DN
DN
DN
DN
FAN 4
FAN 5
FAN 6
POI 4
DN
DN
POI 3
DN
FAN 7
Figure 20 Basic DWDM physical connectivity scenarios
There are two types of DWDM Nodes: Reconfigurable Optical Add-Drop Multiplexers (ROADMs) and
Optical Line Repeaters (OLRs). Each of these two types of DN comprises:
Baseline elements: elements that have a fixed quantity per degree and do not expand with
traffic growth unless that growth involves an increase in degrees. Such elements include
amplifiers, add/drop filters and wavelength selective switches.
Growth elements: these are elements within a degree that can be added to as growth
requires. Such elements include channel cards, controller and chassis.
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