What is high speed network?
"High-speed Internet"
is a generic term used for Internet service that is faster than the
average. One way to determine if a connection is high-speed is to compare it to
the speed of dial-up service. If a connection operates faster than dial-up, it
is often defined as "high-speed."
Why is speed networking important?
Speed networking is designed to
accelerate business contacts through facilitated introductions and
conversations – at speed. A common structure is to rotate all participants in
quick succession so that each person gets the chance to engage one on one with
as many people as possible.
How does speed networking work?
Token-ring networks
A token-ring network is a
local area network (LAN) topology that sends data in one direction throughout a
specified number of locations by using a token.
The token is the symbol of authority
for control of the transmission line. This token allows any sending station in
the network (ring) to send data when the token arrives at that location.
Stations in a token-ring network are
physically connected, typically in a star-wired ring topology, to a wiring
concentrator such as the IBM® 8228 Multistation Access Unit. The concentrator
serves as a logical ring around which data is transmitted at 4 million, 16
million, or 100 million bits per second (Mbps). Each station is connected to
the concentrator typically by shielded twisted pair (STP) cabling.
Full-duplex token ring
In full-duplex token ring, which is
also called DTR (dedicated token ring), switching hubs enable stations to send
and receive data on the network simultaneously. A token-ring switching hub
divides the network into smaller segments. When a station transmits its data
packet, the token-ring switch reads the packet's destination address
information and forwards the data directly to the receiving station. The switch
then establishes a dedicated connection between the two stations, enabling data
to be transmitted and received at the same time. In full-duplex token ring, the
token-passing protocol is suspended. The network in effect becomes a
'tokenless' token ring. Full-duplex token ring increases sending and receiving
bandwidth for connected stations, improving network performance.
Speed networking basically
involves participants gathering together to exchange information.
Participants greet each other in a series of brief exchanges during a set
period of time. During an interaction, participants share their professional
backgrounds and business goals.
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The IBM Token-Ring Network is a high-speed communications network for interconnecting
information processing equipment at a local site (building or campus). The
network uses the IBM Cabling System, including Type 3 specified telephone
media, for physical interconnection, and a token-ring access protocol for network
traffic control. Products are offered for attaching the IBM Personal Computer
to the network. |
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An IBM Personal Computer program that
links the IBM PC Network to the IBM Token-Ring Network. The IBM token-ring network, which is
based on a ring topology with token-access control, is described. In
particular, a star-wired ring topology and the functions of several of the
key physical components that compromise a token-ring network are examined.
The token-access control protocol for regulating data flow on the ring is
explained, including the data frame format and addressing structures,
mechanisms for ensuring token integrity and fair token access to all attached
nodes, and some token-ring performance attributes. The relationship between
the token-ring architecture and systems network architecture (SNA) is also
discussed. Some of the fault detection and isolation capabilities that are
available with the token-ring LAN are also presented. Token bus/IEEE 802.4 Token bus is a popular standard for
token passing LANs. It was standardized by IEEE standard 802.4 and is mainly
used for industrial applications. In a token bus LAN, stations are used to
create a virtual ring, and tokens are then passed from one station to another
using this virtual ring. Every station or node in the token bus network knows
the address of its "left" and "right" station. A node or
station can transmit the data only when it holds a token. The working of the
Token Bus is similar to a token ring. What is Token Bus (IEEE 802.4)? Token Bus (IEEE 802.4) is a network
for implementing token rings over the virtual ring in LANs. The physical
media in a token bus uses coaxial cables and has a bus or tree topology. The
nodes or stations are used to create a virtual ring, and the token is passed
from one node to another node in a sequential manner along this virtual
ring. The addresses of each node's preceding and succeeding stations are
known to them. The token is required for a station to
transmit data. When a node on the virtual ring has nothing to send, the token
is passed on to the next node. A token bus network is similar to the token
ring network but works around the virtual ring instead of a physical ring. Token Passing Mechanism in Token Bus In a computer network, a token is a
brief message that travels among the stations and provides them permission
for transmission. When a station receives a token, if it has data to
transmit, it transmits the data and then passes the token to the following
node or station; otherwise, it just passes the token to the next station. The
diagram below shows how this works. Frame Format of Token Bus The following are the fields in
the frame format of the token bus Preamble – It is
used for bit synchronization. It is a 1-byte field. Start Delimiter – These
bits mark the beginning of the frame. It is a 1-byte field. Frame Control – This
field specifies the type of frame – data frame and control frames. It is a
1-byte field. Destination Address – This
field contains the destination address. It is a 2 to 6 bytes field. Source Address – This
field contains the source address. It is a 2 to 6 bytes field. Data – If 2-byte
addresses are used then the field may be up to 8182 bytes and 8174 bytes in
the case of 6-byte addresses. Checksum – This
field contains the checksum bits which are used to detect errors in the
transmitted data. It is 4 bytes field. End Delimiter – This
field marks the end of a frame. It is a 1-byte field. Ring topology has the following advantages: Data collisions are less likely
because each node sends out a data packet after receiving the token. Under heavy traffic, token passing
makes ring topology perform better than bus topology. The Token-passing Bus Protocol
Functions The token bus protocol offers the following functions: Ring initialization: Ring
initialization is performed when a network is powered on for the first time
and after a catastrophic error. Station addition: Station
addition is selectively performed when a station holding a token allows the
insertion of a new successor station (i.e., a brand-new station with an
address) that lies between that station and its existing successor station. Station removal: Station
removal can be performed by disconnecting it from the LAN or sending a new
successor identifier to the station's predecessor. Recovery mechanisms
establish the appropriate new logical ring configuration in the later
scenario. Recovery and Management: Recovery
from failures such as bus idle (lack of activity on the bus), token-passing
failure (lack of valid frame transmission), the existence of duplicate token,
and the detection of a station with a malfunctioning receiver are all
included in management and recovery. Physical Layer of the Token Bus The physical layer of the token bus
can be made of the conventional 75-ohm coaxial cable that is used for cable
TV. Various modulation techniques are employed. The various modulation
techniques used are multilevel dual binary amplitude-modulated phase shift
keying, phase coherent frequency shift keying, and phase continuous frequency
shift keying. It is possible to get signal speeds in the 1 Mbps, 5 Mbps, and
10 Mbps ranges. The token bus's physical layer is completely incompatible
with the IEEE 802.3 (Ethernet) standard. |
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High-speed LAN
Gives examples for so called
High-speed LANs and describes them. LAN protocols according to IEEE standard
802 are all based on copper transmission media (that is twisted pair or coaxial
cable), which allows data rates of up to 15 Million bits per second (Mbps).
LAN protocols according to IEEE
standard 802 are all based on copper transmission media (that is
twisted pair or coaxial cable), which allows data rates of up to 15
Million bits per second (Mbps). This is too little if special applications
(like picture or video processing) are running or mainframes or minicomputers
should be integrated into the LAN. To get higher transmission rates (up to 100
Mbps and more) it is often necessary to switch to optical fibre media.
This is often done in addition to copper media: according to the needed
performance, devices are connected to different tiers of LANs, not to a single
local network. These tiers provide the necessary performance for the devices
connected to them. Thus, a device with low performance needs can be connected
to a slower - and cheaper - LAN. The single LAN tiers are then interconnected,
which is more cost-effective than using a single LAN fulfilling all possible
performance needs.
There are a few network standards
based upon this optical fiber technology, for example:
Fibre Distributed Data Interface
(FDDI and FDDI-II): can be used in the same way as the common LANs but is often
used as a backbone to connect copper LANs because of its high speed. FDDI always
uses the topology of a ring and a MAC protocol similar to
token ring.
A typical FDDI implementation may look like this:
FDDI-II supports protocols for real time transmission of data.
Fibre Channel
Fibernet II
S-Net
Fasnet and Expressnet
But there are also efforts to speed
up LANs based on copper media, e. g. 100 MBit-Ethernets like 100Base
Fast-Ethernet or 100VG-AnyLAN .
Other possiblities to speed up LANs are discussed in connection to Broadband-ISDN.
Which LAN has the highest data rate?
10 Gigabit Ethernet is the
fastest and most recent of the Ethernet standards. IEEE 802.3ae defines a
version of Ethernet with a nominal rate of 10Gbits/s that makes it 10 times
faster than Gigabit Ethernet. Unlike other Ethernet systems, 10 Gigabit
Ethernet is based entirely on the use of optical fiber connections.
Fast Ethernet is an extension of
the 10-megabit Ethernet standard. It runs on twisted pair or optical fiber
cable in a star wired bus topology, similar to the IEEE standard 802.3i called
10BASE-T, itself an evolution of 10BASE5 (802.3) and 10BASE2 (802.3a).
Fast Ethernet is an extension of the
10-megabit Ethernet standard. It runs on twisted pair or optical
fiber cable in a star wired bus topology, similar to the IEEE
standard 802.3i called 10BASE-T, itself an evolution of 10BASE5 (802.3)
and 10BASE2 (802.3a). Fast Ethernet devices are generally backward compatible
with existing 10BASE-T systems, enabling plug-and-play upgrades from 10BASE-T.
Most switches and other networking devices with ports capable of Fast Ethernet
can perform auto negotiation, sensing a piece of 10BASE-T equipment and
setting the port to 10BASE-T half duplex if the 10BASE-T equipment cannot
perform auto negotiation itself. The standard specifies the use of CSMA/CD for
media access control. A full-duplex mode is also specified and in
practice, all modern networks use Ethernet switches and operate in
full-duplex mode, even as legacy devices that use half duplex still exist.
A Fast Ethernet adapter can be
logically divided into a media access controller (MAC), which deals
with the higher-level issues of medium availability, and a physical layer
interface (PHY). The MAC is typically linked to the PHY by a four-bit
25 MHz synchronous parallel interface known as a media-independent
interface (MII), or by a two-bit 50 MHz variant called reduced
media independent interface (RMII). In rare cases, the MII may be an
external connection but is usually a connection between ICs in a network
adapter or even two sections within a single IC. The specs are written based on
the assumption that the interface between MAC and PHY will be an MII but they
do not require it. Fast Ethernet or Ethernet hubs may use the MII to
connect to multiple PHYs for their different interfaces.
The MII fixes the theoretical maximum
data bit rate for all versions of Fast Ethernet to 100 Mbit/s. The information
rate actually observed on real networks is less than the theoretical
maximum, due to the necessary header and trailer (addressing and
error-detection bits) on every Ethernet frame, and the required interpacket
gap between transmissions.
What are the three 3 types of Fast Ethernet?
100BASE-TX for use with level 5 UTP
cable;
100BASE-FX for use with fiber-optic
cable; and
100BASE-T4 which utilizes an extra
two wires for use with level 3 UTP cable.
Gigabit Ethernet
What is Gigabit Ethernet?
Gigabit Ethernet (GbE), a
transmission technology based on the Ethernet frame format and protocol used in
local area networks (LANs), provides a data rate of 1 billion bits per second,
or 1 gigabit (Gb).
What is the difference between Ethernet and Gigabit Ethernet?
A Fast Ethernet switch can transfer
data packets at a rate of 10 megabits per second. A Gigabit Ethernet
switch transfers data packets at relatively higher speeds of one gigabit per
second. In comparison, a Gigabit Ethernet switch can transfer data packets at
around 100 times faster than a Fast Ethernet switch.
Why do I need Gigabit Ethernet?
Even better, a gigabit
connection allows you to split off an incredibly high-speed internet into
multiple tasks and devices without slowing any one device or streaming session
down. Gigabit ethernet is also highly valuable if you do an extensive amount of
file transfers inside your internal LAN network of computers.
In computer networking, Gigabit
Ethernet (GbE or 1 GigE) is the term applied to
transmitting Ethernet frames at a rate of a gigabit per second.
The most popular variant, 1000BASE-T, is defined by the IEEE
802.3ab standard. It came into use in 1999, and has replaced Fast
Ethernet in wired local networks due to its considerable speed improvement
over Fast Ethernet, as well as its use of cables and equipment that are widely
available, economical, and similar to previous standards.
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