Packet Switched Networks
Ethernet, Fast Ethernet, FDDI and Token Ring often referred to as
traditional LAN, and they are sharing media, sharing of bandwidth shared LAN.
In order to increase bandwidth, often using a network router division, will be
divided into a network of more than one paragraph, each of the networks have
different sub-address, different broadcasting domain, to reduce conflicts on
the network, increase network bandwidth. Micro-paragraph of the network cannot
meet the LAN extension and the new high-bandwidth network applications to the
demand, it is said that "traditional local area network has come to an
end."
In recent years the exchange processes-LAN technology, to address
shared by the LAN network inefficient and can not provide adequate network
bandwidth and network expansion and a series of difficult issues. It
fundamentally changed the structure of shared local area network, to solve the
bandwidth bottleneck. At present, the exchange of Ethernet, token ring
exchange, the exchange of FDDI and ATM, such as the exchange of local area
networks, Ethernet one of the most extensive exchange. LAN exchange has become
the mainstream LAN technology.
Switches provide the ability to bridge the existing network and
increase bandwidth capabilities.
For the LAN switches on the bridge with similar because they all
operate in the data link layer (level 2), M A C-layer, the inspection of all
network traffic into the device address. And the bridge still has some similar
switch to maintain an address on the table and used the information to decide
how to filter and forward LAN flow.
And bridge different, switches using technology to increase the
exchange of data input and output media and installation of the total
bandwidth. General switch delay small forward, the economy and can be divided
into small network of conflict domain, for each workstation to provide higher
bandwidth.
Packet-switched network is the circuit-switched networks and packet
switching network after a new exchange network, which mainly used for data
communications. Packet switching is a store-and-forward of the exchange, it
will at the user's text is divided into a certain length of the packet to
packet for store-and-forward, therefore, than the utilization of
circuit-switched, than when the message exchange Extensions to small, but with
real-time communication capabilities. Packet-switched TDM principle of the use
of statistics, a data link multiplexing into multiple Luojixindao, eventually
forming an Caller, Called party transmission of information between the access
road, called the VC (VC) to achieve data Packet sent.
Packet switching network has the following characteristics:
(1) packet switching with multiple Luojixindao the capacity
utilization rate is high trunk circuits
(2) can be realized packet switching codes of the different online,
the rate between the terminal and a point of order Interoperability;
(3) The packet switching error detection and correction of the
capacity of the transmission circuit is a very small error rate
(4) packet-switched network-management capabilities.
Packet switching the basic business SVC (SVC) and PVC (PVC) two. SVC
as telephone circuit, that is, two data communication terminals to be used when
the first call to establish procedures for circuit (VC), and then sent the
data, communications rewirable procedures used after the removal of VC. PVC as
green, in the net division between the two terminals for the period of the
contract to provide permanent logical connection, no call set-up and rewirable
procedures, the data transmission phase, with the SVC the same.