OT architecture & communications

Design the network around the pipeline.

OT architecture for the six-site Tarong Pipeline, covering communications, segmentation and dedicated operational support.

Sunwater

The constraint

Pump stations, storage, screens and valves depend on communications between distributed sites. Changing those connections also affects operator access, maintenance and the boundary with corporate IT. The architecture needed to account for those dependencies while keeping safety and availability central to the design.

Our design work

Quokka developed the current and target OT network architecture for Sunwater’s six-site Tarong Pipeline. The work brought communications resilience, SCADA and control boundaries, and the services needed to support operations into one design.

Separate corporate access, supervision and control.

ITCorporate

Business systems & corporate workstations

BoundaryOT DMZ

Controlled access between IT and OTRemote access · checked file transfer · application integration

OT · L3/2SCADA

BoondoomaSCADA & operator console

MelroseSCADA & operator console

EllwoodsSCADA & operator console

OT · L1/0Control

PLCs and field equipment across the six locations

BoondoomaOffice, surge tank & pump station

Fish screensBoondooma / Melrose

MelrosePump station & balancing storage

EllwoodsPump station & balancing storage

GoodgerBalancing storage

Tarong HutValve

Future stateOT support

Independent operational servicesOT directory · monitoring · patch distribution · event collection · firewall management

Redrawn from the Tarong design pack: Sunwater’s SCADA and control groupings, with the future OT DMZ and support separation. These are functional zones, not a physical traffic path. The pack assumes completion of the separate site-security programme.

Separate the communications underlay from the protected paths.

ConnectionsUnderlay

LTE private APNExisting site WAN

Corporate uplinkAt extended sites

Starlink internetEgress only · at extended sites

Protected OT communicationsVPN overlay

Inter-site communications and remote access, with defined boundaries.

Field sitesRequired operational communications

Authorised supportControlled access into OT

Target communications design: IPsec connects the sites, with SD-WAN considered as an alternative. Extended sites include corporate infrastructure; connections vary with the role of each site.

The design

Map the operational environment

Document the field sites, PLCs, operator interfaces, SCADA systems and communications paths. Translate the Purdue model into Sunwater’s SCADA and control groupings so the architecture relates to the equipment and services in use.

Design boundaries and connection options

Define the target network separation and VPN overlays, with SD-WAN as an alternative. Consider existing LTE communications and additional connectivity at extended sites alongside the required inter-site and remote-access paths.

Give OT its own support foundation

Develop the future OT DMZ and identity separation, with dedicated monitoring, patch distribution and event collection. Define controlled remote access and file transfer alongside the network boundaries.

The design output

Sunwater received current-state, target-state and future-state architecture views for Tarong. The design connects the communications decisions to segmentation, remote support and the services OT needs to operate, giving the team a basis for planning the changes together.

Six-site operational scope mapped

SCADA, control and IT/OT boundaries defined

Communications and OT support dependencies considered together

OT network architecture developed by Quokka Advisory for Sunwater. This story covers the architecture and recommendations.

Inside the delivery

The engineering decisions.

The architecture relates communications and security boundaries to a six-site water asset, with separate paths for control, maintenance and supporting services.

Map the pipeline equipment to operational functions

Quokka mapped PLCs, operator interfaces, SCADA servers and communications across six locations. The design translates the Purdue reference model into Sunwater’s SCADA and control groupings, so the separation relates to the systems people operate and maintain. Safety and availability guide the permitted communications and ownership of each boundary.

Distinguish site communications from remote support

The material maps existing LTE connectivity through a private APN, then develops inter-site and remote-access VPN overlays. The target design considers additional connectivity at extended sites and identifies SD-WAN as an alternative to IPsec. These are architecture options for the distributed asset, with the separate site-security programme recorded as a dependency.

Give OT independent support dependencies

The future-state design separates OT identity from the corporate directory and includes dedicated monitoring, patch distribution and event collection. That makes the support services needed by OT explicit alongside the field network, rather than treating corporate infrastructure as an assumed dependency.

Control people and files crossing into OT

The OT DMZ provides controlled remote access and service integration. The recommendations include multifactor authentication, separate corporate and operational workstations, and a mechanism to check files entering or leaving OT. These controls accompany the zones and permitted communications in the architecture recommendations.

What needs to work better?

Talk to us about the environment, the constraint and the change.

Talk to Quokka