Phan Vĩnh Thuần Computer Network 1
CHƯƠNG 7
CÁC CÔNG NGHỆ ETHERNET
ETHERNET TECHNOLOGIES
Phan Vĩnh Thuần Computer Network 2
Overview
•
Ethernet has been the most successful LAN
technology largely because of its simplicity of
implementation compared to other
technologies. Ethernet has also been
successful because it has been a flexible
technology that has evolved to meet changing
needs and media capabilities. This module
introduces the specifics of the most important
varieties of Ethernet. The goal is not to convey
all the facts about each type of Ethernet, but
rather to develop a sense of what is common
to all forms of Ethernet.
Phan Vĩnh Thuần Computer Network 3
•
Changes in Ethernet have resulted in major
improvements over the 10-Mbps Ethernet of
the early 1980s. The 10-Mbps Ethernet
standard remained virtually unchanged until
1995 when IEEE announced a standard for a
100 Mbps Fast Ethernet. In recent years, an
even more rapid growth in media speed has
moved the transition from Fast Ethernet to
Gigabit Ethernet. The standards for Gigabit
Ethernet emerged in only three years. An

limits.
–
List 10BASE-T wiring parameters.
–
Describe the key characteristics and
varieties of 100-Mbps Ethernet
Phan Vĩnh Thuần Computer Network 6
–
Describe the evolution of Ethernet.
–
Explain the MAC methods, frame formats, and
transmission process of Gigabit Ethernet.
–
Describe the uses of specific media and
encoding with Gigabit Ethernet.
–
Identify the pinouts and wiring typical to the
various implementations of Gigabit Ethernet.
–
Describe the similarities and differences
between Gigabit and 10 Gigabit Ethernet.
–
Describe the basic architectural considerations
of Gigabit and 10 Gigabit Ethernet.
Phan Vĩnh Thuần Computer Network 7
7.1.10-Mbps and 100-Mbps Ethernet
7.1.1. 10Mbps Ethernet
•
10BASE5, 10BASE2, and 10BASE-T
Ethernet are considered Legacy Ethernet.

operation but is not required.
Phan Vĩnh Thuần Computer Network 13
•
SQE is active:
–
Within 4 to 8 microseconds following a normal
transmission to indicate that the outbound
frame was successfully transmitted
–
Whenever there is a collision on the medium
–
Whenever there is an improper signal on the
medium. Improper signals might include
jabber, or reflections that result from a cable
short.
–
Whenever a transmission has been interrupted
Phan Vĩnh Thuần Computer Network 14
•
All 10 Mbps forms of Ethernet take octets
received from the MAC sublayer and
perform a process called line encoding.
Line encoding describes how the bits are
actually signaled on the wire. The simplest
encodings have undesirable timing and
electrical characteristics. So line codes
have been designed to have desirable
transmission properties. This form of
encoding used in 10 Mbps systems is
called “Manchester.”

architectural design is of the utmost
importance when implementing a mixed-
media network. It becomes easier to
violate maximum delay limits as the
network grows.
Phan Vĩnh Thuần Computer Network 19
•
The timing limits are based on parameters
such as:
–
Cable length and its propagation delay
–
Delay of repeaters
–
Delay of transceivers
–
Interframe gap shrinkage
–
Delays within the station
Phan Vĩnh Thuần Computer Network 20
•
10-Mbps Ethernet operates within the
timing limits offered by a series of not more
than five segments separated by no more
than four repeaters. This is known as the 5-
4-3 rule. No more than four repeaters may
be connected in series between any two
distant stations. There can also be no more
than three populated segments between
any two distant stations.

However, the distance limitations were
favorable and this prolonged its use in
certain applications.
Phan Vĩnh Thuần Computer Network 25
•
Because the medium is a single coaxial
cable, only one station can transmit at a
time or else a collision will occur.
Therefore, 10BASE5 only runs in half-
duplex resulting in a maximum of 10 Mbps
of data transfer.