CAT8 is often presented as the obvious upgrade from CAT6A. For datacentre designers, the reality is more nuanced: the two categories are built for different jobs, and choosing the wrong one adds cost without adding capability.
How do CAT6A and CAT8 compare?
| CAT6A | CAT8 | |
|---|---|---|
| Bandwidth | 500 MHz | 2000 MHz |
| Ethernet applications | Up to 10GBASE-T | 25GBASE-T and 40GBASE-T |
| Maximum channel | 100 m | 30 m (24 m link + cords) |
| Shielding | U/UTP or shielded | Shielded only (F/UTP or S/FTP) |
| Standards | TIA-568.2-D Category 6A; ISO/IEC 11801-1 Class EA | TIA-568.2-D Category 8; ISO/IEC Class I and II |
| Typical use | Horizontal cabling, server and access links, PoE | Short switch-to-server links in the same or adjacent rack |
Why is CAT8 limited to 30 metres?
At 2000 MHz, insertion loss climbs steeply. The standard trades distance for speed: CAT8 was designed for the short links inside a row of racks, not for building-wide horizontal cabling. If a link is longer than 30 metres, CAT8 does not support 25G or 40G — and CAT6A will deliver 10G over the full 100 metres at lower cost.
Where does CAT8 make sense?
- Top-of-rack and end-of-row switch-to-server links where 25GBASE-T or 40GBASE-T equipment is planned.
- Short, high-density links where the operator prefers RJ45-style structured copper over direct-attach cables.
It is worth checking equipment availability before specifying CAT8. Many datacentres run 25G and faster server links over fibre or direct-attach copper (DAC) cables rather than twisted pair, so the switch ports may not exist for a 25GBASE-T design.
Where is CAT6A the better choice?
- Horizontal cabling to work areas, wireless access points and building systems.
- 10G server connections and storage networks.
- PoE applications, including PoE++ at up to 90 W, where conductor size and construction keep temperature rise under control.
- Any link longer than 30 metres.
Does shielding matter in the datacentre?
In dense pathways, alien crosstalk between neighbouring cables is the main limiter on CAT6A performance. Pair-foiled constructions — U/FTP and S/FTP — give the largest margin and are a common choice for high-density datacentre installations. CAT8 is shielded by definition.
The short answer
Use CAT6A for anything longer than 30 metres and for 10G and PoE workloads. Use CAT8 only for short links where 25G or 40G copper equipment is genuinely planned. Channeltech manufactures CAT6A in all five shielding configurations, as well as CAT7, CAT7A and CAT8 S/FTP. Our CAT6A selector tool recommends a construction for your environment in six questions.