Ethernet Standardization
Notwithstanding
its technical merits, timely standardization was instrumental to the success of
Ethernet. It
required well-coordinated and partly competitive activities in
several standardization bodies such as the
IEEE, ECMA, IEC, and finally ISO.
The
"DIX-group" with Gary Robinson (DEC), Phil Arst (Intel), and Bob
Printis (Xerox) submitted the so-
called "Blue Book" CSMA/CD
specification as a candidate for the LAN specification. Since IEEE
membership is open to all
professionals, including students, the group received countless comments on
this
technology.
Networks
Simple switched Ethernet
networks, while a great improvement over repeater-based Ethernet, suffer from
single points of failure, attacks that trick switches or hosts into sending data
to a machine even if it is not
intended for it, scalability and security issues
with regard to broadcast
radiation and multicast traffic, and
bandwidth choke points where a lot
of traffic is forced down a single link.
Advanced networking features in
switches and routers combat these issues through a number of means
including spanning-tree
protocol to maintain the
active links of the network as a tree while allowing physical
loops for
redundancy, port security and protection features such as MAC lock down and
broadcast
radiation filtering, virtual LANs to keep different classes of users separate while
using the same physical
infrastructure, multi-layer switching to route between different classes and link aggregation to add bandwidth
to overloaded links and to
provide some measure of redundancy.
Standards
The vast majority of customer has LAN's that employ Ethernet as the network
protocol - a few uses Token
Ring. At least 90% of these networks are
10 BASE-T. The LAN sits behind the router and hub or high-
speed
Ethernet switch, and the workstations are connected in a star topology.
Actually, most networks
have replaced the Cat 3 cables with Cat 5. Both
Cat 3 and 5 cables have 4 un-shielded, twisted pairs of
copper wires and use the
RJ-45 connector, as shown below:
Comparison
Often
referred to as Thick
net, 10Base5 was the
first incarnation of Ethernet technology. The industry used
thick net in the
1980s until 10Base2 Thin net
appeared. Compared to thick net, thin net offered the
advantage of thinner (5
millimeters vs. 10 millimeters) and more flexible cabling, making it easier to
wire
office buildings for Ethernet.
The most common
form of traditional Ethernet, however, is 10Base-T. 10Base-T
offers better electrical
properties than thick net or Thin net, because
10Base-T cables utilize unshielded twisted pair (UTP) wiring
rather than
coaxial. 10Base-T also proved more cost effective than alternatives like fiber
optic cabling.
The table below
details these traditional Ethernet technologies. Besides the type of cable
involved, another
important aspect of Ethernet networking is the segment length. A segment is a network
connection made by
a single unbroken network cable. Ethernet cables and segments
can only span a limited physical distance,
after which transmissions will
likely fail due to line noise, reduced signal strength and other degradation. Per
the Ethernet specifications, manufacturers of Ethernet equipment must meet the
below minimum
specifications for segment length.
Numerous other
lesser-known Ethernet standards exist, including 10Base-FL, 10Base-FB, and 10Base-
FP for fiber optic networks and 10Broad36 for broadband
(cable television) cabling.
Gigabit Ethernet
Whereas
Fast Ethernet improved traditional Ethernet from 10 Megabit to 100 Megabit
speed, Gigabit
Ethernet boasts the same order-of-magnitude improvement over
Fast Ethernet by offering speeds of 1000
Megabits (1 Gigabit). Gigabit Ethernet
was first made to travel over optical and copper cabling, but the
1000Base-T
standard successfully supports it as well. 1000Base-T uses Category 5 cabling
similar to 100
Mbps Ethernet, although achieving gigabit speed requires the use
of additional wire pairs.
100BASE-FX:
100BASE-FX is a version of Fast Ethernet over optical fiber. It uses a 1300 nm near-infrared (NIR) light
wavelength transmitted via two strands of optical fiber, one
for receive (RX) and the other for transmit (TX).
Maximum length is 400 meters
(1,310 ft.) for half-duplex connections (to ensure collisions are
detected),
and 2 kilometres (6,600 ft) for full-duplex over multi-mode
optical fiber. 100BASE-FX
uses the same
4B5B encoding and NRZI line code that 100BASE-TX does. 100BASE-FX
should use SC, ST, LC,
MTRJ or MIC connectors with SC being the preferred option.
100BASE-FX is not compatible with
10BASE-FL, the 10 MBit/s versions over optical fiber.
100BASE-SX:
100BASE-SX is a version of Fast Ethernet over
optical fiber. It uses two strands of multi-mode optical
fiber for receive and
transmit. It is a lower cost alternative to using 100BASE-FX, because it uses
short
wavelength optics which are significantly less expensive than the long
wavelength optics used in 100BASE-
FX. 100BASE-SX can operate at distances up to
550 meters (1,800 ft.).
100BASE-SX uses the same
wavelength as 10BASE-FL, the 10 Mbit/s versions over optical fiber. Unlike
100BASE-FX, this allows 100BASE-SX to be backwards-compatible with 10BASE-FL.
Because of the shorter wavelength
used (850 nm) and the shorter distance it can support, 100BASE-SX
uses
less expensive optical components (LEDs instead of lasers) which makes it an
attractive option for
those upgrading from 10BASE-FL and those who do not
require long distances.
Ethernet Standardization
Notwithstanding
its technical merits, timely standardization was instrumental to the success of
Ethernet. It
required well-coordinated and partly competitive activities in
several standardization bodies such as the
IEEE, ECMA, IEC, and finally ISO.
The
"DIX-group" with Gary Robinson (DEC), Phil Arst (Intel), and Bob
Printis (Xerox) submitted the so-
called "Blue Book" CSMA/CD
specification as a candidate for the LAN specification. Since IEEE
membership is open to all
professionals, including students, the group received countless comments on
this
technology.
Networks
Simple switched Ethernet
networks, while a great improvement over repeater-based Ethernet, suffer from
single points of failure, attacks that trick switches or hosts into sending data
to a machine even if it is not
intended for it, scalability and security issues
with regard to broadcast
radiation and multicast traffic, and
bandwidth choke points where a lot
of traffic is forced down a single link.
Advanced networking features in
switches and routers combat these issues through a number of means
including spanning-tree
protocol to maintain the
active links of the network as a tree while allowing physical
loops for
redundancy, port security and protection features such as MAC lock down and
broadcast
radiation filtering, virtual LANs to keep different classes of users separate while
using the same physical
infrastructure, multi-layer switching to route between different classes and link aggregation to add bandwidth
to overloaded links and to
provide some measure of redundancy.
Standards
The vast majority of customer has LAN's that employ Ethernet as the network
protocol - a few uses Token
Ring. At least 90% of these networks are
10 BASE-T. The LAN sits behind the router and hub or high-
speed
Ethernet switch, and the workstations are connected in a star topology.
Actually, most networks
have replaced the Cat 3 cables with Cat 5. Both
Cat 3 and 5 cables have 4 un-shielded, twisted pairs of
copper wires and use the
RJ-45 connector, as shown below:
Comparison
Often
referred to as Thick
net, 10Base5 was the
first incarnation of Ethernet technology. The industry used
thick net in the
1980s until 10Base2 Thin net
appeared. Compared to thick net, thin net offered the
advantage of thinner (5
millimeters vs. 10 millimeters) and more flexible cabling, making it easier to
wire
office buildings for Ethernet.
The most common
form of traditional Ethernet, however, is 10Base-T. 10Base-T
offers better electrical
properties than thick net or Thin net, because
10Base-T cables utilize unshielded twisted pair (UTP) wiring
rather than
coaxial. 10Base-T also proved more cost effective than alternatives like fiber
optic cabling.
The table below
details these traditional Ethernet technologies. Besides the type of cable
involved, another
important aspect of Ethernet networking is the segment length. A segment is a network
connection made by
a single unbroken network cable. Ethernet cables and segments
can only span a limited physical distance,
after which transmissions will
likely fail due to line noise, reduced signal strength and other degradation. Per
the Ethernet specifications, manufacturers of Ethernet equipment must meet the
below minimum
specifications for segment length.
Numerous other
lesser-known Ethernet standards exist, including 10Base-FL, 10Base-FB, and 10Base-
FP for fiber optic networks and 10Broad36 for broadband
(cable television) cabling.
Gigabit Ethernet
Whereas
Fast Ethernet improved traditional Ethernet from 10 Megabit to 100 Megabit
speed, Gigabit
Ethernet boasts the same order-of-magnitude improvement over
Fast Ethernet by offering speeds of 1000
Megabits (1 Gigabit). Gigabit Ethernet
was first made to travel over optical and copper cabling, but the
1000Base-T
standard successfully supports it as well. 1000Base-T uses Category 5 cabling
similar to 100
Mbps Ethernet, although achieving gigabit speed requires the use
of additional wire pairs.
100BASE-FX:
100BASE-FX is a version of Fast Ethernet over optical fiber. It uses a 1300 nm near-infrared (NIR) light
wavelength transmitted via two strands of optical fiber, one
for receive (RX) and the other for transmit (TX).
Maximum length is 400 meters
(1,310 ft.) for half-duplex connections (to ensure collisions are
detected),
and 2 kilometres (6,600 ft) for full-duplex over multi-mode
optical fiber. 100BASE-FX
uses the same
4B5B encoding and NRZI line code that 100BASE-TX does. 100BASE-FX
should use SC, ST, LC,
MTRJ or MIC connectors with SC being the preferred option.
100BASE-FX is not compatible with
10BASE-FL, the 10 MBit/s versions over optical fiber.
100BASE-SX:
100BASE-SX is a version of Fast Ethernet over
optical fiber. It uses two strands of multi-mode optical
fiber for receive and
transmit. It is a lower cost alternative to using 100BASE-FX, because it uses
short
wavelength optics which are significantly less expensive than the long
wavelength optics used in 100BASE-
FX. 100BASE-SX can operate at distances up to
550 meters (1,800 ft.).
100BASE-SX uses the same
wavelength as 10BASE-FL, the 10 Mbit/s versions over optical fiber. Unlike
100BASE-FX, this allows 100BASE-SX to be backwards-compatible with 10BASE-FL.
Because of the shorter wavelength
used (850 nm) and the shorter distance it can support, 100BASE-SX
uses
less expensive optical components (LEDs instead of lasers) which makes it an
attractive option for
those upgrading from 10BASE-FL and those who do not
require long distances.
Posted at 12:49 | by
viralnom
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