Category 5e, 6, 6A, 7, 8? – What’s the Difference?

03 May 2018

There are a vast array of revisions to the ethernet cable; each an improvement on their predecessor – But what is the difference between them?

Take a look below for a brief explanation on the differences between common ethernet cables.

Common Features

Despite there being lots of revisions of ethernet cable, they all share some fundamental common features.
For example:

  • All cables consist of 4 Twisted Pairs
  • They are all commonly presented by an RJ45 Connector
  • There is a maximum Channel Length of 100M (This includes installed cabling and patch leads to hardware)
  • And all variants are backwards compatible with each other – Although they will only run at the capabilities of the ‘slowest’

Category 5e / Class D

Category 5e (short for Category 5 Enhanced) was ratified in 2001 and replaced Category 5.

It was built on the foundations that Category 5 laid down.

Category 5e operates at 100MHz, much like Category 5 did.

However, Category 5 was only ever designed for 10/100Mb applications.

Cat5 was officially superseded in 2001 and is no longer manufactured or commonly found.

But what improvements did Category 5e bring?

Firstly, it brought gigabit support (1000Mb). This helped give network devices a considerable increase in bandwidth availability.

To enable it to do this, it reduced crosstalk by increasing the twist rate of the pairs inside the cable.

To this day, Category 5e is still installed within business networks.

With up to Gigabit transmission speeds, it is still suitable for a large number of applications such as printers, PDQ machines etc.

Although for companies that are installing for the future, we’re seeing a rise in Category 6 and above being specified.

Cat5e cable comes in both U/UTP & F/UTP forms, both offering distinct differences and suiting different applications.

With the ratification of 802.3bz (What is 802.3bz?), there is an aim to support 2.5G over Category 5e however, when (and IF) we may see this in the real world, is still up for debate.

Category 6 / Class E

Taking Cat5e up a notch, we have Cat6 Cabling running at 250MHz.

The largest differences between Category 6 and Category 5e is conductor size, and an internal spline (separating member).

These differences allow Cat6 to minimise crosstalk and support up-to a 10G throughput (55m max channel length).

However, it’s worth remembering that the 55m is a maximum limit and the quality of the installation is the limiting factor, when specifying purely for a 10G network Category 6A is best suited.

Category 6 cable, much like Cat5e can be bought in both U/UTP & U/FTP varieties – And it’s also backwards compatible, operating at 10/100/10000Mbs where required.

Category 6A / Class Ea

We’re starting to see a rise in workstations shipping with 10G NICs.

If you want a network infrastructure to support these and future high-bandwidth devices, Category 6A is your safe bet.

Category 6A operates at a much higher, 500MHz frequency.

Designed for 10G applications from day dot (unlike its predecessors), it improves hugely on alien crosstalk, which Cat6 struggled with at high frequencies.

Category 6A comes in a wide range of varieties. All the way from U/UTP, to S/FTP.

We wouldn’t recommend U/UTP purely because of the popularity in PoE and the fact it is usually just as expensive as F/UTP.

F/UTP and higher designs are much better at heat dissipation and aren’t as susceptible to alien crosstalk.

Supporting 10G of bandwidth, up to a maximum channel length of 100m – It is also able to support the theoretical throughput of the latest wireless access points.

Most organisations feel that Category 6A will support most of their business needs for years to come, and therefore commonly this is the highest cable you’ll likely see.

Category 7? Category 7A? / Class F(a)

You may question the question marks…

Cat7 and Cat7A is a technology that hasn’t taken off quite as much as everyone expected.

Firstly, it has never been recognised in the TIA/EIA-568 standard. That’s fairly major…

It also has three recognised connector types, all of which aren’t the common RJ45… GG45, ARJ45 & TERA.

The reason for the variation on the connector type comes down to one very simple complexity, crosstalk.

With Class F(a) providing up to a huge 1000MHz, crosstalk proved to be an issue at the connector end.

With the standard RJ45, 8P8C connector, all the pins are placed right next to one another, allowing for crosstalk to manifest, and at these frequencies it proved to be troublesome.

For this reason, different connector types were pursued, however this fatally flawed the easy backwards compatibility that previous classes allowed.

For this reason, we’ve never seen the addition of Class F, or Class Fa for that matter within TIA/EIA-568.

And although it’s still within the ISO Standards, its lack of truly backwards compatible connector has hindered it’s jump into common use.

Until we see hardware such as switches & NICs being shipped with a connector that is supported, we likely won’t see a true take off of Cat7 cabling.

Category 8

There are now initial movements of Category 8 from the leading cable vendors. Supporting a huge 2000MHz and speeds of up to 40Gbps.

However, in the ISO/IEC standards, there are two separate classes and two separate cables to support them.

Category 8.1 supports Class I. Category 8.2 supports Class II.

Unlike Cat6a, there is no unshielded variety.

Only Category 8.1 is compatible with the RJ45 connector, and therefore we feel that it shall be used the most.

Category 8.2 is terminated with the same connectors as Category 7(a), TERA & GG45.

While all previous categories of balanced twisted-pair copper cabling have supported a maximum channel length of 100m, to support its maximum speed of 40Gbps, there is a limit to the channel length to the tune of 30m.

For this reason, Category 8 is unlikely to be used as an installed cable, more for patching over short distances where fibre transceivers are more expensive than RJ45.

Conclusion

While there’s still a case for Category 5e to be installed, it’s certainly getting left behind with theoretical speed.

At the current time, both Category 5e and Category 6 support a maximum of a Gigabit at 100M Channel Lengths (in mainstream active hardware [routers, switches, NICs]).

While this, in theory, puts them on a level playing field.

Category 6’s increased frequency, internal spline and larger core size make it far more future-proof for higher bandwidth and PoE (Power over Ethernet) applications.

While Category 6 does support 10G speed, we wouldn’t specify it for this purpose.

Due to its lack of shielding in U/UTP form, in large bundles, alien cross talk can be present.

Shielding being present doesn’t just reduce the risk of alien crosstalk. It also aids heat dissipation.

Therefore, with the rise of PoE and daily increasing demands in speed.

If you’re installing for the future, a shielded, high frequency solution is your best bet.

Category 6A Cabling provides both of these. It’s high-frequency provides huge bandwidth capabilities over a distance of up to 100M. And it comes (in most cases) as a shielded solution ensuring alien crosstalk and heat dissipation is at a maximum.

It is also backwards compatible with most mainstream switches and routers due to it’s RJ45 Connector.

In plain and simple terms, if you’re looking for the future (at least 5 Years) or your environment is already a high bandwidth one.

Stick with Category 6A.

However, sometimes the investment of Category 6A and above may not see a return over a short-term premises lease; therefore the more cost-effective option such as Category 5e or Category 6 may suit your needs better.

As with any design, however, it is genuinely beneficial to engage with a qualified design engineer as every environment brings its own set of unique challenges and design criteria.

If you want to speak with one of our design engineers, give us a call on 01604 422722.