Calculate maximum cable run length for a given medium and signal loss tolerance.
Each cabling standard has a maximum supported run length that depends on the target data rate — copper twisted-pair cables (Cat5e/6/6a/7/8) are limited primarily by signal attenuation and crosstalk, which gets worse at higher frequencies needed for faster speeds (e.g. Cat6 supports 100m at 1 Gbps but drops to 55m for reliable 10 Gbps operation). Fiber standards (OM3/OM4/OS2) support much longer runs since light in glass suffers far less attenuation than electrical signals in copper, with single-mode fiber (OS2) supporting many kilometers regardless of speed within reason.
Standard-specific maximum length
max_length is a lookup value per (cable standard, target speed) combination, not a single formula
Cat6 was designed and certified primarily for Gigabit Ethernet at 100m. At 10 Gbps, alien crosstalk and attenuation become severe enough that reliable operation is only guaranteed up to about 55m — Cat6a was specifically engineered with better shielding/twist geometry to support the full 100m at 10 Gbps.
Single-mode fiber carries light through a much narrower core in a single propagation mode, avoiding the modal dispersion that limits multimode fiber's distance at high speeds — single-mode links routinely span kilometers to tens of kilometers, versus multimode's typical few hundred meters.
The cable standard sets an upper bound, but the actual transceiver (e.g. specific SFP+ optic) and PHY chipset must also support that distance — always check the transceiver's own datasheet distance rating, since some optics are designed for shorter reach even over compliant cabling.
No — Cat8 is designed for short data center interconnects (25/40 Gbps up to about 30m) between switches and servers in the same or adjacent racks, not general horizontal office cabling, where Cat6a is the more common modern choice.