Structured cabling is the backbone of data centre infrastructure, ensuring seamless connectivity and reliability in the digital age. At the heart of this framework lies the Telecommunications Industry Association’s TIA-942-B standard, a globally recognised standard that provides comprehensive guidelines for the planning, design, and implementation of cabling infrastructure within data centres.
TIA-942-B outlines specific requirements and recommendations for various ratings of cabling infrastructure, including cabling topology, cable types, pathways, spacing, grounding, and more. Each rating defines the level of redundancy, reliability, and availability required for different data centre applications. It helps data centre operators and designers establish a solid foundation to support the DC’s reliable and efficient operation.
Here are the different ratings according to TIA-942-B…
Rated 1: Basic site infrastructure
At the entry level, Rated 1 describes a data centre configuration where single capacity components and a single, non-redundant distribution path serve the computer equipment. This level provides limited protection against physical events.
Single path cabling between equipment and the distribution network
No redundancy in power and cooling systems
Rated 2: Redundant capacity component
Advancing from Rated 1, Rated 2 is a data centre setup with redundant capacity components alongside a single, non-redundant distribution path serving the computer equipment. This configuration enhances protection against physical events, although it maintains a single path for data transmission, which limits its ability to fully mitigate downtime risks.
Redundant power and cooling components
Single path cabling to distribution network
Rated 3: Concurrently maintainable
Rated 3 marks a significant stride towards robustness, with redundant capacity components and multiple independent distribution paths serving the computer equipment. Typically, only one distribution path serves the computer equipment at any time.
This level ensures concurrent maintainability, allowing planned removal, replacement, or servicing of every capacity component, including elements of the distribution path, without disrupting ICT capabilities to end users. It provides protection against most physical events.
Multiple paths for cabling and distribution network
Redundant power and cooling with concurrent maintainability
Rated 4: Fault tolerant
At the apex of the Rated hierarchy, Rated 4 epitomises fault tolerance and maximum uptime. With redundant capacity components and multiple independent distribution paths serving the computer equipment, all of which are active, this tier ensures continuous operations. It allows for concurrent maintainability and can withstand one fault anywhere in the installation without causing downtime. It provides protection against almost all physical events.
Multiple active paths for cabling and distribution
Fully redundant power and cooling with fault tolerance
The backbone of connectivity
In addition to these ratings, TIA-942-B also outlines specific criteria for cabling design and installation, including the use of structured cabling, cable management systems, and labelling requirements. The standard also mandates the testing and certification of cabling infrastructure. By adhering to TIA-942-B, data centre operators can align their cabling infrastructure with the demands of their specific application, providing the necessary level of reliability and availability for their critical data centre services.
Within the context of TIA-942-B, the equipment and distribution network encompasses the physical components that make up the data centre infrastructure. This includes servers, storage devices, switches, routers, and other networking devices that are used to deliver data centre services to end-users. The distribution network refers to the cabling and connectivity infrastructure that facilitates the interconnection of the equipment within the data centre environment.
Comprising diverse elements like copper and fiber optic cabling, patch panels, connectors, and assorted networking hardware, the distribution network facilitates the seamless routing of data traffic between the various data centre components. Engineered as a reliable and high-performance connectivity backbone, the distribution network plays a pivotal role in swiftly and efficiently transmitting data between various devices within the data centre.
Redundancy and resilience in cabling infrastructure
In TIA-942-B, the different rated levels of cabling infrastructure are categorised based on the level of redundancy and availability of the distribution network. As we progress through the rated levels, the cabling infrastructure becomes more redundant and resilient, with multiple pathways and redundant components ensuring the continuity of data centre services even in the event of a failure or outage.
In both Rated 3 and Rated 4, the cabling infrastructure requires multiple active paths for both the cabling and distribution network. This means that there are at least two separate cabling pathways connecting each piece of active equipment to the distribution network, and both of these routes are actively used to transmit data.
These pathways are physically separate from each other and may be routed through different parts of the data centre. The distribution network itself must also have at least two distinct paths linking it to the core network and the Internet. These paths should be physically separate, with redundant hardware and cabling to safeguard uninterrupted data centre operations even if one path fails. In addition to these active paths, a Rated 4 data centre may also have an additional path for backup or emergency use.
Continuity and compliance
By providing multiple paths for cabling and distribution networks, Rated 3 and Rated 4 data centres can ensure that their infrastructure is highly available and resilient, with redundant components and failover mechanisms in place to minimise downtime in the event of an equipment failure or outage. This requirement helps to ensure that data centre services are fortified to maintain high availability and operational continuity even in the face of unexpected events.
Structured cabling forms the cornerstone of data centre operations, with TIA-942-B rated levels providing a roadmap for resilience and reliability. The third revision of the 942 Standard (TIA-942-C) will soon be published, so watch this space for updates. And for more insight on meeting the demands of modern data centres, get in touch.
By Stefan Naude
