Information Technology Reference
In-Depth Information
In this chapter, we will cover the special structured cabling techniques you must
employ to support gigabit and 10 Gb speeds. In the local area network (LAN),
Ethernet is clearly the primary topology for these speeds, so we will concentrate on
the structured cabling standards that support Gigabit Ethernet and 10 Gigabit
Ethernet. ATM at OC-12c is another topology that is available, although it is not
quite gigabit speed. Likewise, OC-192 is virtually 10 Gb, too, but these technolo-
gies can be supported in the LAN with the same techniques we use for comparable
Ethernet speeds.
Gigabit structured cabling techniques will be covered first, and the 10 Gb tech-
niques will be covered later in the chapter.
Gigabit
refers to a data transfer speed of 1,000,000,000 bits per second, or 1
Gbps. The corresponding Ethernet technology meets this definition exactly; it oper-
ates at 1 Gbps. Technically, ATM at OC-12c is at 622 Mbps data rate, so it is about
two-thirds gigabit speed. In fact, the standards revision TIA-568-A (and now TIA-
568-C as well) incorporates wiring technologies that accommodate both of these
gigabit-class speeds. This standard specifies the provision of two cables to each
workstation outlet, one of which may be fiber. Although it is up to the cabling sys-
tem designer to include the fiber, the provision of multimode fiber makes it easy to
implement either of the common gigabit-class technologies, Gigabit Ethernet or
ATM/OC-12c. But, what about copper? Well, thanks to the tight specifications of
this standard, we are now using Category 5e and higher cabling for gigabit copper
networks for both Ethernet and ATM-622. Network speeds go up by a factor of 10
about every five years (Fig 12.1).
10 Gigabit
refers to a data transfer speed of 10,000,000,000 bits per second,
or 10 Gbps. In the LAN, “10 GigE” (as it is often called) Ethernet operates at that
1,000
100
10
1
1980
1985
1990
1995
2000
2005
2010
Year
FIGURE 12.1
Time-speed curve.
