Why ethernet cables have different speed?

Architect, Install and Maintain Bicsi Cable Plants
Todays Acceptable Cable Types

“Why ethernet cables have different speeds?”, you ask. Well the difference in certifiable cable speeds can be summarized by straws and fire hoses analogy; straws are designed for small sips and firehoses are designed to dump lots of water. I have included several charts below to explain the differences in ethernet cable speed. There are several items that make “cables go faster”: Quality of the Copper, Lack of Shielding or Shielding of the Cable, Number of Pairs used, Twists per pair, and Frequency of the Signal sent. Most of the cable we are installing today (1/2022) is Cat 6 or Cat 6A. Cat 7 and higher is very expensive for the cable, connectors, and network gear standpoint. We do install 40 Gbit – 100 Gbit equipment and cabling in our datacenter engagements. If you do not have Cat 6 cable installed in your facility, then you need to consider replacing your cable plant in the near future. The pressures from the demand for speed and moving large quantities of data dictate better cable.

Install and Design Cable Plants
Basic Cable Types

As one can see from the left chart Cat 5 and Cat5e cable is mostly obsolete due to its carrying capacity. Even though most desktops run only at 1 Gbit speeds other equipment like servers, SANs, NASs, and WiFi are all requiring 10 Gbit speeds to service infrastructure needs.

I have also included a chart of UTP (Untwisted Pair, fairly obsolete), S/UTP (Shielded Untwisted Pair, eliminates electrical interference), STP (Twisted Pair – Cat 5 and up), S/STP (Shielded Twisted Pair Cable, Best and Most Expensive)

Unshielded, Untwisted, Shielded, and Shielded Twisted Pair


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