What do I choose .. Cat5E, Cat6 or Cat6A? 

Category 5 was first published as a standard in 1995. It appeared in:

• ANSI/TIA/EIA-568-A
• EN 50173
• ISO 11801

Note that in the American standard (TIA) the term ‘Category’ refers to the individual product performance (cables and connectors etc.) and the overall channel performance. For example Category 5 defines a range of electrical performances up to 100 MHz. In the European standard, EN 50173 and the international ISO standard, ‘Category’ only refers to a product performance. The overall link and channel performance is rated by ‘Class’. So for example a Cat 5 cable terminated with Cat 5 connecting hardware would give a Class D channel and link performance. The original Category 5 standard was suitable for LAN transmission standards up to 155 Mb/s, including all the various forms of fast Ethernet up to 100 Mb/s. When gigabit Ethernet was introduced in 1998 (1000BASE-T) it was discovered that the original Cat 5 specification wasn’t good enough to guarantee error-free performance. 

Extra technical requirements were added to the original Cat 5 specification, such as Return Loss, Delay, Delay Skew and Power Sum Crosstalk measurements to ensure reliable operation of gigabit Ethernet. The improved range of parameters became known as enhanced Category 5 or Cat5e. Note that Cat5e is still a 100 MHz channel, but with a tighter electrical specification. In 1999/2000 all the standards were updated to take into account the newCat 5 requirements. Until September 2002 the relevant standards were: 

• ANSI/TIA/EIA-568-A Addendum 5, this was replaced by ANSI/TIA/EIA- 568-B in summer 2001
• EN 50173 Amendment 1 2000
• ISO 11801 Edition 1.2 

After September 2002 the relevant standards were: 

• ANSI/TIA/EIA-568-B
• EN 50173 2nd Edition
• ISO 11801 2nd Edition 

The expression ‘Cat5e’ was only ever meant to be marketing ‘shorthand’ to differentiate it from ‘old’ Cat 5. The old Cat 5 standards are now obsolete and nobody (in theory) makes these products anymore. This means that the term ‘Cat5e’ will gradually fall out of use because today’s standard products all meet the latest Category 5 /Class D specifications and are, by default, Cat5e.  Category 6/Class E was introduced in the summer of 2002. Cat 6 requires the same electrical parameters as Cat5e but with a required performance up to 250 MHz. Cat 6 is defined in the following standards:

• ANSI/TIA/EIA-568-B2-1
• EN 50173 2nd Edition
• ISO 11801 2nd Edition 

Category 6/Class E will offer LAN data rates up to 10 Gb/s, but over a limited distance, and also gives a superior video transmission performance. Category 6A will be finalised shortly and will offer a system performance of 500 MHz and is designed to go hand in hand with the new ten gigabit Ethernet standard, 10GBASE-T. It is an ideal data centre technology. PKF’s clients should ask themselves the question: “Am I happy with the LAN technology of today?” If the answer is yes then that client will find Cat5e adequate for their needs. That said we know that LAN technology changes significantly on about a two year cycle, so it the user wants a cabling system that will see them through the foreseeable future, encompassing the next generation of LAN technology, all without recabling their building, then Category 6 would be the technology for them. TIA 942 and EN 50173-5, the data centre standards, require that Cat 6A is the minimum performance for data centres and computer rooms.

Technology	Bandwidth Offered	Standard	Max Speed	Typical LAN Protocol	Distance Limitations
Old Cat 5	100 MHz	obsolete	100 Mb/s	100BASE-TX	100 m
Cat5e	100 MHz	2002 standard	1000 Mb/s	1000BASE-T	100 m
Cat 6	250 MHz	2002 standard	10,000 Mb/s	10GBASE-T 1000BASE-T Fibre Channel	Limited to 37m for 10GBASE- T.Otherwise 100m
Cat6A	500 MHz	2008 standard	10,0.0 Mb/s	10GBASE-T Fibre Channel	100 m

What is Cat 7 and does it exist?

Siemon’s category 7A/class FA TERA cabling solution is the highest-performing copper cabling system available. Supplying over 1000MHz of bandwidth per pair, the TERA cabling system more than doubles the bandwidth requirements of that category 7 standard, exceeding even the pending category 7A standard (the pending class FA standard specifies Siemon’s TERA interface). Not only does TERA easily support network speeds in excess of 10Gb/s, it is capable of supporting the coming 40Gb/s standards. TERA provides the lowest total cost of ownership of any copper cabling solution. Because of TERA’s enhanced ability to support the application standards most likely to follow 10GBASE-T, it can be expected to outlast all other varieties of twisted-pair copper cabling. The longer a cabling plant can support expanding network needs, the longer a user can avoid a costly cabling upgrade. Category 7A/class FA carries a minimum 15-year projected lifecycle while other copper systems are estimated to sustain 10 years or less. It is also completely compatible with current RJ45 network equipment.

With just one cable and outlet, Siemon’s category 7A/class FA TERA cabling solution can support up to 4 separate applications. Fitting within a standard RJ footprint, the combination of the TERA outlet and cord options allows extremely simple facilitation of cable sharing. As with traditional cabling channels, all four pairs of each cable are terminated in a single outlet. However, unlike an RJ interface, the TERA outlet can support up to 4 one-pair voice or video cords, 2 two-pair VoIP or data cords or a combination of the two, without the need for additional splitters or adapters.  The TERA cabling system is the only copper cabling system to pass TEMPEST high-security testing. This indicates that TERA cabling should meet all TEMPEST shielded cabling requirements in even the most demanding high-security situations. This enables a more cost effective copper solution opposed to traditional fibre cabling used for TEMPEST environments.