the 10BASE-T configuration. 100BASE-TX carries 100
Mbps of traffic in half-duplex mode. In full-duplex mode,
100BASE-TX can exchange 200 Mbps of traffic. The concept of
full duplex will become increasingly important as Ethernet
speeds increase. Web Links 100BASE-TX
http://www.ethermanage.com/ethernet/ 100quickref/ ch10qr_1.htm
Content 7.1 10-Mbps and 100-Mbps Ethernet
7.1.8 100BASE-FX At the time copper-based Fast
Ethernet was introduced, a fiber version was also desired. A
fiber vervsion could be used for backbone applications,
connections between floors and buildings where copper is less
desirable, and also in high noise environments. 100BASE-FX was
introduced to satisfy this desire. However, 100BASE-FX was
never adopted successfully. This was due to the timely
introduction of Gigabit Ethernet copper and fiber standards.
Gigabit Ethernet standards are now the dominant technology for
backbone installations, high-speed cross-connects, and general
infrastructure needs. The timing, frame format, and
transmission are all common to both versions of 100 Mbps Fast
Ethernet. 100BASE-FX also uses 4B/5B encoding. In Figure notice
the highlighted waveform in the example. The top waveform has
no transition, which indicates that a binary 0 is present. In
the second waveform, a transition is in the center of the
timing window. A binary 1 is represented by a transition. In
the third waveform, there is an alternating binary sequence. In
this example it is more obvious that no transition indicates a
binary 0 and the presence of a transition is a binary 1. Figure
summarizes a 100BASE-FX link and pinouts. Fiber pair with
either ST or SC connectors is most commonly used. 200 Mbps
transmission is possible because of the separate Transmit and
Receive paths in 100BASE-FX optical fiber. Web Links
100BASE-FX Components http://www.ethermanage.com/ethernet/
100quickref/ch11qr_3.html
Content 7.1 10-Mbps
and 100-Mbps Ethernet 7.1.9 Fast Ethernet
architecture Fast Ethernet links generally consist of a
connection between a station and a hub or switch. Hubs are
considered multi-port repeaters and switches are considered
multi-port bridges. These are subject to the 100 m UTP media
distance limitation. A Class I repeater may introduce up to 140
bit-times of latency. Any repeater that changes between one
Ethernet implementation and another is a Class I repeater. A
Class II repeater may only introduce a maximum of 92 bit-times
latency. Because of the reduced latency it is possible to have
two Class II repeaters in series, but only if the cable between
them is very short. As with 10 Mbps versions, it is possible to
modify some of the architecture rules for 100 Mbps versions.
However there is virtually no allowance for additional delay.
Modification of the architecture rules is strongly discouraged
for 100BASE-TX. 100BASE-TX cable between Class II repeaters may
not exceed 5 meters. Links operating in half duplex are not
uncommon to find in Fast Ethernet. However, half duplex is
undesirable because the signaling scheme is inherently full
duplex. Figure shows architecture configuration cable
distances. 100BASE-TX links can have unrepeated distances up to
100 m. The widespread introduction of switches has made this
distance limitation less important. If workstations are located
within 100 m of a switch, the 100 m distance starts over at the
switch. Since most Fast Ethernet is switched, these are the
practical limits between devices. Lab Activity Lab
Exercise: Introduction to Fluke Network Inspector This lab is a
tutorial demonstrating how to use the Fluke Networks Network
Inspector (NI) to discover and analyze network devices within a
broadcast domain. Lab Activity Lab Exercise:
Introduction to Fluke Protocol Inspector This lab is a tutorial
demonstrating how to use the Fluke Networks Protocol Inspector
to analyze network traffic and data frames. Interactive
Media Activity Drag and Drop: Fast Ethernet Architecture
After completing this activity, the student will understand the
architecture of Fast Ethernet. Web Links Ethernet Design
Rules http://www.bostontech.net/assets/files/
articles/TechBrief1_P1.pdf
Content 7.2 Gigabit
and 10-Gigabit Ethernet 7.2.1 1000-Mbps
Ethernet The 1000-Mbps Ethernet or Gigabit Ethernet
standards represent transmission using both fiber and copper
media. The 1000BASE-X standard, IEEE 802.3z, specifies 1 Gbps
full duplex over optical fiber. The 1000BASE-X standard, IEEE
802.3z, specifies 1 Gbps full duplex over optical
fiber.1000BASE-TX, 1000BASE-SX, and 1000BASE-LX use the same
timing parameters, as shown in Figure . They use a 1 nanosecond
(0.000000001 seconds) or 1 billionth of a second bit time. The
Gigabit Ethernet frame has the same format as is used for 10
and 100-Mbps Ethernet. Depending on the implementation, Gigabit
Ethernet may use different processes to convert frames to bits
on the cable. Figure shows the Ethernet frame formats. The
differences between standard Ethernet, Fast Ethernet and
Gigabit Ethernet occur at the physical layer. Due to the
increased speeds of these newer standards, the shorter duration
bit times require special considerations. Since the bits are
introduced on the medium for a shorter duration and more often,
timing is critical. This high-speed transmission requires
frequencies closer to copper medium bandwidth limitations. This
causes the bits to be more susceptible to noise on copper
media. These issues require Gigabit Ethernet to use two
separate encoding steps. Data transmission is made more
efficient by using codes to represent the binary bit stream.
The encoded data provides synchronization, efficient usage of
bandwidth, and improved Signal-to-Noise Ratio characteristics.
At the physical layer, the bit patterns from the MAC layer are
converted into symbols. The symbols may also be control
information such as start frame, end frame, medium idle
conditions. The frame is coded into control symbols and data
symbols to increase in network throughput. Fiber-based Gigabit
Ethernet (1000BASE-X) uses 8B/10B encoding which is similar to
the 4B/5B concept. This is followed by the simple Non-Return to
Zero (NRZ) line encoding of light on optical fiber. This
simpler encoding process is possible because the fiber medium
can carry higher bandwidth signals. Web Links 1000-Mbps
Ethernet http://grouper.ieee.org/groups/802/3/
tutorial/march98/mick_170398.pdf
Content 7.2
Gigabit and 10-Gigabit Ethernet 7.2.2
1000BASE-T As Fast Ethernet was installed to increase
bandwidth to workstations, this began to create bottlenecks
upstream in the network. 1000BASE-T (IEEE 802.3ab) was
developed to provide additional bandwidth to help alleviate
these bottlenecks. It provided more "speed" for
applications such as intra-building backbones, inter-switch
links, server farms, and other wiring closet applications as
well as connections for high-end workstations. Fast Ethernet
was designed to function over existing Cat 5 copper cable and
this necessitated that cable would pass the Cat 5e test. Most
installed Cat 5 cable can pass 5e certification if properly
terminated. One of the most important attributes of the
1000BASE-T standard is that it be interoperable with 10BASE-T
and 100BASE-TX. Because Cat 5e cable can reliably carry up to
125 Mbps of traffic, getting 1000 Mbps (Gigabit) of bandwidth
was a design challenge. The first step to accomplish 1000BASE-T
is to use all four pairs of wires instead of the traditional
two pairs of wires used by 10BASE-T and 100BASE-TX. This is
done using complex circuitry to allow full duplex transmissions
on the same wire pair. This provides 250 Mbps per pair. With
all four-wire pairs, this provides the desired 1000 Mbps. Since
the information travels simultaneously across the four paths,
the circuitry has to divide frames at the transmitter and
reassemble them at the receiver. The 1000BASE-T encoding with
4D-PAM5 line encoding is used on Cat 5e or better UTP.
Achieving the 1 Gbps rate requires use of all four pairs in