2 Cat6 Cables

[Aidan Guy]

If i were to connect 2 COMMS cabinets together using 2 Cat6 cables, what is the maximum speed of data transfer between the 2 cabinets?

we need to rewire an office and if we use only 1 cabinet we require nearly 5 miles of cable so we are thinking of using 2 cabinets and linking the gigabit ports in the patch panels in each cabinet using cat 6 cables and were unsure if this would keep the data transfer rate high.

Any help would be appreciated,

Cheers

[johnwill]

With plain old CAT5e you can have gigabit connections, and CAT6 would yield the same throughput. Obviously, it won't hurt to use CAT6.

[Aidan Guy]

How can Cat5e cable use a gigabit output? I thought its maximum was 100MB/Sec!!

If Cat5e can transfer data at a gigabit/sec why would we want to use Cat6?

[johnwill]

CAT6 is good for longer runs. If you look closely at the specifications for gigabit, you'll see that CAT5e is plenty. Here's something I just lifted from a site...

Consider the history of 100Mbit/sec Fast Ethernet. The first generation adapters were more expensive than 10Mbit/sec Ethernet. The second generation Fast Ethernet adapters were about the same cost as standard Ethernet adapters. Since a Fast Ethernet adapter could operate at either 10 or 100Mbit/sec, there was no economical reason not to deploy Fast Ethernet adapters regardless of whether the network infrastructure was 10 or 100Mbit/sec. Fast Ethernet switches on the other hand, took a few years longer to come down in price to the point where there was very little difference between a Fast Ethernet switch and a standard Ethernet switch.

Today, Gigabit Ethernet is at the intermediate stage where adapters are inexpensive relative their Fast Ethernet counterpart, but switches are not. It is expected that new single chip silicon devices will enable inexpensive Gigabit Ethernet switches in the near future. In the mean time, it can be desirable to directly connect two computer systems with Gigabit Ethernet adapters without a switch.

The IEEE 802.3ab 1000Base-T standard is designed to work with most Category 5 UTP cables. Obviously, the ability to work with Cat 5 cables is of enormous value because it is deployed so pervasively. Cat 5 specifies a cable that supports a 100MHz signal with certain attenuation and impedance characteristics (100Ω) and other requirements.

The fact that signaling occurs at 100Mbaud does not necessarily imply that the data transmission rate is also 100Mbit/sec (Mbps). First, some form of encoding is necessary to ensure that long streams of zeros or ones do not cause the clocks on each device to fall out of synchronization. Ethernet uses Manchester encoding, which requires one extra bit for each bit of data, actually signals at 20Mbaud with a data transmission rate of 10Mbps. The 100Base-TX version of Fast Ethernet uses 4B/5B encoding and operates at 125Mbaud with a data transmission rate of 100Mbps.

Depending on the signal-to-noise ratio; advanced signaling techniques employing multiple voltage levels can achieve higher transmission rates than the signaling rate. The 1000Base-T implementation of Gigabit Ethernet employs a 5-level coding scheme that effectively contains 2-bits, excluding the encoding overhead, and 4 parallel signals to enable 1Gbit/sec data transmission rates on the same 125Mbaud signaling as 100Base-TX.

Despite the considerable effort made to enable 1000Base-T to operate on cables meeting the Cat 5 specifications, some additional specifications were required (Cat 5e). Fortunately, most Cat 5 cables manufactured actually meets the additional Cat5e specifications. So Gigabit Ethernet should work with most Cat 5 cables, but if new cables are being purchased, one should check that the cables meet the Cat 5e specification. Cables that exceed the Cat 5e specification rated for 350MHz may be only moderately more expensive than Cat 5, while Cat 6 cables that support 500MHz are more expensive.

Given that Gigabit Ethernet should be able to use Cat 5e, 350MHz and Cat 6 cables, one might ask whether a standard Ethernet or Fast Ethernet cross-over cable can be employed to connect two Gigabit Ethernet adapters directly. A quick look at the Cat 5e and 350MHz cross-over cable products available shows that only 10 and 100Mbps Ethernet modes are supported. So the question remains, what is necessary to connect two Gigabit Ethernet adapters directly? It turns out that the answer is standard Cat 5e or better patch cables!