Switching
Switching is
process of interconnecting two devices. It acts like a
medium between two devices. Switching is of 3 types:
1.Circuit switching
It includes cross bar
switching and multistage switching. Disadvantage of
cross bar switching is that the number of holes are
comparatively more than the multistage switching.
2.Packet Switching
Packet shown below:
|
Source address |
destination
|
flag bits |
CRC's |
Error&flow
control |
In this type of
switching the data is transferred in form of packet
which contains source address , destination address,
flag bits, CRC's etc.
It is further divides in
Data gram switching and the Virtual Circuit approach. In
data gram switching the packets move independently and
the protocol organizes them at the destination point.
3.Message Switching
This type of switching
is nowadays a history. In it entire message is
transfered at once through IMP's.
Switches may operate at
one or more OSI model layers, including physical, data
link, network, or transport . A device that operates
simultaneously at more than one of these layers is
called a multilayer switch, although use of the term is
diminishing.
Asynchronous Transfer
Mode and ATM Switching:
Atm Switching is a switching technology that allows
voice, data, image, and video traffic to be combined
into evenly sized cells for high-speed transmission over
one access circuit. Each 53 byte cell contains 48 bytes
of payload and 5 bytes of control information.
