10BASE-5 or (Thick Ethernet)
10BASE-5 is the original Ethernet system. It employs a quarter of an inch
diameter, 50 ohm coax cable ( with minimum bend radius of 10 inches).
10BASE-5 segments can run in length up to 500 meters with as many as 100
transceiver connections spaced at lease 2.75 yards apart.
10BASE-5 transceivers access the media by piercing the thick coaxial cable.
These transceiver taps are known as vampire taps. Since they don’t actually
require breaking the physical cable, the electrical signals over the cable
are typically fairly clean.
10BASE-5 systems were originally envisioned to be cheap and fairly easey to
build. The large cable needed simply to be run by rooms where computing
equipment would be located. Taps would be made into the cable by using
external transceivers. As it turned out, the requirement of an external
transceiver and the thick cable, which was expensive and difficult to work
with, limited the use of 10BASE-5.
10BASE-2 (Thin Ethernet)
Thin Ethernet was a fairly popular specification and is still used in many
environments today. With a maximum segment length of 203.5 yards, it
requires that the 50 ohm cable be only .2 inches thick ( a bend radius of
two inches). It also uses standard BNC connectors and “T’s” to provide
access to the media. Typically, T’s are connected directly to the back of
network interface cards, thus eliminating the need for an external
A maximum of 30 transceivers may be inserted onto a Thin Ethernet segment
and must be spaced at least 20 inches apart. 3Com hardware is able to
handle slightly longer segments, up to 220 yards in length. Unfortunately,
mixing other vedor’s equipment into an environment where cable runs exceed
203.5 yards can cause problems. For this reason, keeping total lengths to
203.5 yards is recommended.