Structured Cabling

Cat5e

Category5e has now been with us since 1992. Cat5e or class D is still the technology of choice for thousands of smaller local area networks (LAN) where, during the network’s lifetime, there is no likely need for greater than Gigabit Ethernet and, to be honest, in many offices and small companies, 100mb/s is still perfectly adequate and will be for some years.

Cat5e is also a great commercial choice for short-term networks where, for example, a company cables-up a temporary or short term rented building – knowing that they only need the network for two or three years and then they’re moving out. So, for them, there is no commercial sense in future proofing the network.

Cat6

Cat 6 has never had an application (such as a specific speed of Ethernet) of its own. Instead, it became a significantly better solution for Gigabit Ethernet – offering the safety margin of ‘headroom’ that Cat 5e lacks.

With larger conductors, Cat 6 is also better for power over Ethernet (PoE) applications where its cables do not get as hot (and it should always be remembered that when data cables get warm it significantly degrades their data performance and the length of channel that can be supported!).

So, for installations where Gigabit is going to suffice for all foreseeable business or operational requirements (and where reliability rather than cheapness is the main driver) Cat6 is only a little more expensive than Cat5e but gives a much more robust engineering solution.

Cat6A

Cat 6A and class EA cabling systems have been deployed by forward-looking risk-hedging enterprises in both the backbone and the horizontal.

In enterprise backbones with links of 100m or less, 10Gb/s Ethernet is ideal with the cost of copper nic’s (network interface cards) about to become a fraction of those for fibre.

10GbE will undoubtedly become the network interface of choice for PC manufacturers – which means that Cat6A should be the cabling system of choice for the majority of organisations.

CCA Cables

WARNING
There are many unscrupulous distributors now importing and selling Copper Clad Aluminium (CCA) cables as Cat5e and Cat6 but since they are not constructed of pure annealed copper conductors they cannot be classed as Cat5e or Cat6.

CCA has higher attenuation properties than pure copper cable and this will result in more packets of data having to be retransmitted when it is corrupted or lost at the physical layer. This effect is particularly prevalent on longer cable channels on or near the 100mtr maximum and will at best lead to a slower network for most users of CCA twisted pair cable.

Although no testing has been done on the use of CCA wire for Power over Ethernet applications the higher attenuation properties bring about some frightening possibilities, particularly in applications such as IP CCTV where power is continuously drawn through network cables 24 hours a day, 7 days a week, 365 days of the year using a cable with higher attenuation properties than intended for use with the IEEE802.3af standard, let alone IEEE802.3at, makes very real the possibility that heat will build up faster than it can be dissipated with potentially disastrous consequences

Fibre Optics

The following are Ethernet applications supported by different classes and categories of fibre optics and their maximum channel lengths.

Multimode
Ethernet ApplicationOM1OM2OM3OM4
1000Base-SX (Gigabit)275m550m550m1100m
10GBase-SR/SW (10 Gigabit)32m82m300m550m
Singlemode
Ethernet ApplicationOS1OS2
1000Base-LX (Gigabit)2,000m5,000m
10GBase-LX4 & LR/LW (10 Gigabit)2,000m10,000m
10GBase-ER/EW (10 Gigabit) 2,000m22,250m

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