Token Ring~ Explained

Token ring local area
network (LAN)
technology is a protocol
which resides at the data
link layer (DLL) of the
OSI model . It uses a
special three-byte frame
called a token that
travels around the ring.
Token-possession grants
the possessor
permission to transmit
on the medium. Token
ring frames travel
completely around the
loop.
Initially used only in IBM
computers, it was
eventually standardized
with protocol IEEE
802.5 .
The data transmission
process goes as follows:
Empty information
frames are
continuously circulated
on the ring.
When a computer
has a message to send,
it seizes the token. the
computer will then be
able to send the frame.
The frame is then
examined by each
successive workstation.
The workstation that
identifies itself to be
the destination for the
message copies it from
the frame and changes
the token back to 0.
When the frame gets
back to the originator,
it sees that the token
has been changed to 0
and that the message
has been copied and
received. It removes the
message from the
frame.
The frame continues
to circulate as an
"empty" frame, ready to
be taken by a
workstation when it has
a message to send.
The token scheme can
also be used with bus
topology LANs.
A type of computer network in
which all the computers are
arranged (schematically) in a
circle. A token, which is a special
bit pattern, travels around the
circle. To send a message, a
computer catches the token,
attaches a message to it, and then
lets it continue to travel around
the network.
Also see token passing.
For network diagrams, see Network
Topology Diagrams in the Quick
Reference section of Webopedia.
(2) When capitalized, Token Ring
refers to the PC network
architecture developed by IBM. The
IBM Token-Ring specification has
been standardized by the IEEE as
the IEEE 802.5 standard.
Definition: Token Ring is a data
link technology for local area
networks (LANs) . It operates at
layer 2 of the OSI model .
How Token Ring Works
Unlike all other standard forms of
LAN interconnects, Token Ring
maintains one or more common
data frames that continuously
circulates through the network.
These frames are shared by all
connected devices on the network
as follows:
Characteristics of Token Ring
Networks
Token Ring was developed by IBM
during the 1980s as an alternative
to Ethernet . Starting in the 1990s,
it significantly decreased in
popularity and gradually was
phased out of business networks
as Ethernet technology began to
dominate LAN designs.
Standard Token Ring supports only
up to 16 Mbps. In the 1990s, an
industry initiative called High
Speed Token Ring developed
technology for extending Token
Ring to 100 Mbps equal to
Ethernet, but insufficient interest in
the marketplace existed for HSTR
products and the technology was
abandoned.