multiSwitch – user manual
© TOPEX 2008 7
1
BASE CONCEPTS
In order to create a quick background of networks and data communications we detail below a
few base concepts related to the network switching technology, packet switching, IP telephony,
compression modes or IP voice coding.
Data communication is a new communication mode combining the computer and
communication, which is the foundation upon which various computer networks can be set up.
The data communication network has been developing for over 30 years. In the course when
human beings enter the information society, data communication is playing a more and more
important role.
1.1 Network switching technology
In a wide area, data communication is to transmit data from a source node to the destination
via the intermediate switching node network. Such a switching node does not care about contents of
data.
Its objective is to provide switching facilities for mobile data between nodes. A termination
device for communication can be called a site. A site can be a computer, terminal, telephone or
another communication device.
A switching device providing communication is called a node. They form a topology after being
connected with each other via transmission links. Each site can be connected with a node. The
collection of all nodes is called a communication network.
In a switching communication network, the data entering the network from a site via inter-node
switching is sent to the destination after being routed. From a simple network, we can specify that:
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Some nodes are only connected to other nodes. The only task of these nodes is to complete
internal data exchange. Other nodes are connected to one or more sites. Except the exchange
function, these nodes also receive data from the connected site and delivers data to the
connected site;
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Generally, the multi-channel multiplexing is adopted for inter-node links. We can also adopt the
frequency division multiplexing (FDM) or time division multiplexing (TDM) mode. In addition, the
network is not all connected, i.e., there is no direct link between each possible node pair.
However, it is always hoped that there are more than one path between each pair of sites to
increase the network reliability.
In the wide area network, two different technologies are adopted: circuit switching and packet
switching. Along the path from the source to destination, there are differences between the modes of
switching information from one line to another for different nodes.
Since the major multiSwitch bearer network is based on the packet switching network, we will
primarily describe the packet switching mode below.
