Full motion video for video conferencing requires, typically, at least 25 Mb/sec. That means that a legacy Ethernet, at 10 Mbps/sec, can only deliver poor quality real-time video. With 100 Mbps/sec, however, you can be watching a broadcast presentation in one window while you're in conference with three people in three other windows (for a total of 100 megabits of bandwidth).

Consider a file server that requires 0.6 Mb/sec (6 million bits per second; 60% utilization on a 10 Mb/sec Ethernet). With a 100 Mb/sec Ethernet this server can now utilize interface hardware that can pump data down the pipe at a greatly increased rate.

It seems clear that the evolution of the industry is moving away from 10 Mb/sec Ethernet and towards the 100 Mb/sec (or higher) rates of data transfer. This section of the compendium discusses 100 Mb/sec Ethernet technology

Virtually everyone who uses Ethernet has wished from time to time that their network had a higher bandwidth. When Ethernet was being designed in the late 1970s, 10Mbps seemed immense. With today's bandwidth-intensive multimedia applications, or even with just the departmental server, that number sometimes is barely adequate. Yes, faster network technologies were available, but they were complicated and expensive. Then came Fast Ethernet.

Anyone who understands classic Ethernet already understands much about Fast Ethernet. Fast Ethernet uses the same cabling and access method as 10Base-T. With certain exceptions, Fast Ethernet is simply regular Ethernet - just ten times faster! Whenever possible, the same numbers used in the design of 10Base-T were used in Fast Ethernet, just multiplied or divided by ten. Fast Ethernet is defined for three different physical implementations.

The Implementations of Fast Ethernet:

• 100BASE-TX: Category 5
• 100BASE-FX: Multimode fibre
• 100BASE-T4: Category 3

Probably the most popular form of Fast Ethernet is 100BASE-TX. 100BASE-TX runs on EIA/TIA 568 Category 5 unshielded twisted pair, sometimes called UTP-5. It uses the same pair and pin configurations as 10Base-T, and is topologically similar in running from a number of stations to a central hub.

As an upgrade to 10Mbps Ethernet over multimode fibre (10Base-F), 100BASE-FX is Fast Ethernet over fibre. Single duplex runs are supported up to 400m and full duplex runs are supported for up to 2km.

Fast Ethernet is possible on Category 3 UTP with 100BASE-T4. There is a popular misconception that Fast Ethernet will only run on Category 5 cable. That is true only for 100BASE-TX. If you have Category 3 cable with all four pairs (8 wires) connected between station and hub, you can still use it for Fast Ethernet by running 100BASE-T4. 100BASE-T4 sends 100Mbps over the relatively slow UTP-3 wire by fanning out the signal to three pairs of wire.

This "demultiplexing" slows down each byte enough that the signal won't overrun the cable. Category 3 cable has four pairs of wire, eight wires total, running from point to point. 10Base-T only uses four wires, two pairs. Some cables only have these two pairs connected in the RJ-45 plug. If the category 3 cabling at your site has all four pairs between hub and workstation, you can use Fast Ethernet by running 100BASE-T4.

Please select on of the following sections:

Unshielded Twisted Pair (UTP) cable is most certainly by far the most popular cable around the world. UTP cable is used not only for networking but also for the traditional telephone (UTP-Cat 1). There are seven different types of UTP categories and, depending on what you want to achieve, you would need the appropriate type of cable. UTP-CAT5e is the most popular UTP cable which came to replace the old coaxial cable that was not able to keep up with the constant growing need for faster and more reliable networks.

Characteristics of UTP

The characteristics of UTP are very good and make it easy to work with, install, expand and troubleshoot and we are going to look at the different wiring schemes available for UTP, how to create a straight through UTP cable, rules for safe operation and a lot of other cool stuff !

So let's have a quick look at each of the UTP categories available today along with their specifications:

Figure 1. The Different UTP Categories and their specifications

Category 1/2/3/4/5/6/7 – a specification for the type of copper wire (most telephone and network wire is copper) and jacks. The number (1, 3, 5, etc) refers to the revision of the specification and in practical terms refers to the number of twists inside the wire (or the quality of connection in a jack).