ISO/IEC TR 11801-9907:2019

Overview

ISO/IEC TR 11801-9907:2019 is a Technical Report published by the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC). The standard focuses on the specifications for direct attach cabling within generic cabling systems for customer premises. It defines direct attach cabling as a cable with connectors at each end, which connects two pieces of equipment directly without any intermediate connecting hardware.

This document references ISO/IEC 11801-1 for performance specifications across multiple Classes (D, E, EA, F, FA, I, II) and provides additional informative limits for Class I direct attach cabling for short reach mode applications such as 25GBASE-T and 40GBASE-T.

Key Topics

• Direct Attach Cabling Definition:

  • Cable configuration with connectors at both ends.
  • No patch panels or intermediate connections.
  • Used to connect two active devices directly.

• Performance Specifications:

  • Aligned with ISO/IEC 11801-1 for Classes D, E, EA, F, FA, I, and II.
  • Specifies requirements such as return loss, insertion loss, NEXT (near-end crosstalk), ACR (attenuation crosstalk ratio), propagation delay, and others.
  • Provides informative (guidance) limits for Class I cabling to support short reach high-speed Ethernet (5m for 25GBASE-T/40GBASE-T).

• Testing and Verification:

  • Performance verification referenced to ISO/IEC 14763-4.
  • Laboratory and field performance assessment approaches.
  • Testing is recommended, especially when using components below ISO/IEC 11801-1 specifications or to confirm capacity for application support.

• Applicable Classes:

  • Covers a range of performance classes supporting various data rates and applications, from basic office networking to high-speed data center links.

Applications

Direct attach cabling, as specified in ISO/IEC TR 11801-9907:2019, offers practical benefits in several environments:

• Data Centers:

  • Enables low-latency, high-performance links between switches, servers, and storage using a simple cable assembly.
  • Ideal for short-distance, high-speed Ethernet connectivity, including emerging 25GBASE-T and 40GBASE-T applications.

• Telecommunications Rooms & Equipment Racks:

  • Reduces installation complexity by removing intermediate patching or cross-connection.
  • Facilitates direct device-to-device communications for critical applications.

• Enterprise Networks:

  • Used where direct links are needed, such as between network devices in the same cabinet or room.
  • Supports reliable connections in high-density environments by minimizing signal loss and interference.

• Test and Measurement Scenarios:

  • Useful in environments where temporary, high-performance links are required for equipment validation or certification.

With clearly defined performance criteria aligned to international cabling standards, organizations can confidently deploy direct attach cables knowing they meet current and emerging networking requirements.

Related Standards

For organizations and professionals implementing or specifying direct attach cabling, the following standards are particularly relevant:

• ISO/IEC 11801-1: Information technology - Generic cabling for customer premises - Part 1: General requirements

  • The foundational standard for structured cabling systems, referenced throughout ISO/IEC TR 11801-9907.

• ISO/IEC 14763-4: Implementation and operation of customer premises cabling - Part 4: Measurement of end to end (E2E) links

  • Prescribes test methods for verifying performance, including direct attach configurations.

• ISO/IEC/IEEE 8802-3:2017/AMD3: Information technology - Standard for Ethernet - Physical layers for 25 Gb/s and 40 Gb/s operation (25GBASE-T, 40GBASE-T)

  • Defines application requirements directly supported by Class I direct attach cabling.

These related standards offer the necessary technical framework to design, install, and verify direct attach cabling that complies with international best practices for performance, safety, and interoperability.