From an OT perspective the move to standardise on Ethernet for distributed control has enabled the performance advances needed in enterprise IT to become available to OT. The Gigabit Ethernet (GBE) standard has become the norm for most modern OT network backbones with the opportunity to increase 20 fold if needed.
In practice few OT systems require anything close to the performance available with GBE. In fact the link speed is only a factor in the applications performance, far more relevant are the limitations imposed by the Transmission Control Protocol’s (TCP) Window Size. This can fixed be as small as 8KB in Automation devices; meaning the 10X speed inhancement of a GBE backbone over Fast Ethernet has only a marginal impact to the Round Trip Time RTT and therefore end to end performance.
Ok, so GBE / 10GBE Ethernet performance is not infinite but, all things considered, it’s pretty close.
Having access to significant amounts of spare capacity in the OT network backbone introduces the opportunity for the network to service multiple applications across a common (albeit segmented) backbone. Network security controls are maintained through the configuration of Virtual LANs that can segment the network by application and router firewall to allow interconnection on a ‘needs only’ basis. With most application services now digitized the opportunity is there to deliver multiple across a common infrastructure.
A single well secured and monitored network infrastructure that can seamlessly support autonomous applications whether they are industrial, building service or digital security related systems.
The coexistence of digital camera systems, access control, intrusion detection, intercom, lighting control, metering and a raft of other building service, reduces complexity and lowers overall cost.
In a major building services network in the City of London IT4A condensed 13 building services, from BMS to lift media and window blind control, cross a single high speed and resilient building services network. Individual building service contractors had visibility of all their own maintained assetts but no other finally controlled access to head end servers was provided to the authorised corporate users.
The result is reduction in equipment, power, space and heat generation, a consistency of network design across all contractors, consistency in security from a specialist OT network Company with broad expertise. This means a single quarterly maintenance visit for all 12 building service networks, one network support Company and one agreement to provide controlled remote access. What’s not to like?