Cat 8.1
Ethernet Cables · 9 specs
Direct Answer
Category 8.1 (Cat 8.1) is an Ethernet cabling standard defined in ANSI/TIA-568-C.2-1 (Category 8) and ISO/IEC 11801 Class I. Operating at 2000 MHz (2 GHz), it supports 25GBASE-T and 40GBASE-T data rates over a 30-meter channel using backward-compatible 8P8C (RJ45) shielded connectors.
Source: ANSI/TIA-568-C.2-1 (2016) / ISO/IEC 11801-1 Class I / IEEE 802.3bq · Last reviewed Aug 28, 2026
Specs
| Frequency Bandwidth | 2000 MHz |
| Max Bandwidth / Data Rate | 40 Gbps |
| Supported Physical Layers | 25GBASE-T / 40GBASE-T |
| Max Channel Length | 30 m |
| Permanent Link Max Length | 24 m |
| Standard Connector | 8P8C (RJ45 shielded) |
| Channel Classification | ISO/IEC Class I / ANSI/TIA Category 8 |
| Shielding Requirement | Shielded (F/UTP, S/FTP, or F/FTP) |
| Backward Compatibility | Cat 6a, Cat 6, Cat 5e RJ45 ports |
Datacenter Focus and 30-Meter Limit
Cat 8.1 was developed under IEEE 802.3bq (25G/40GBASE-T) specifically for datacenter switch-to-server architectures (Top-of-Rack and End-of-Row). To achieve 2000 MHz bandwidth, the standard sacrificed 100-meter reach, limiting the channel to 30 meters (consisting of a 24-meter permanent link and 6 meters of total patch cord length).
Class I vs Class II Distinction
Cat 8.1 (Class I) preserves full backward compatibility with existing RJ45 infrastructure. It uses standard 8P8C connector dimensions with enhanced shielding and compensation circuits to control internal crosstalk at 2 GHz, allowing seamless fallback to 10GBASE-T, 1000BASE-T, or 100BASE-TX.