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AUDIO NETWORKING OVERVIEW Multimedia networks synopsis Long distance communications have been an obsession of humanity for a long time, with the earliest methods of relaying messages consisting of smoke signals or drumming. Although primitive these methods use an agreed standard between transmitter and receiver, encoding and decoding a message which is the basic principle still used today. In 1451 Johannes Gutenberg invented the printing press, allowing widespread access to mobile information, exampling the “one-to-many” motive in communication. 1844 introduced the Telegraph, after Samuel Morse and his colleague’s relayed electrical impulses “Morse code”. The telephone, developed by Graham Bell in 1876, domesticated by the 1940s, transmitted the human voice on shared party lines. The journey to modern telecommunications is punctuated not only with major milestones but also with ideas that were ahead of their time. For instance, Bell’s wireless telephone call in 1880 eventually led to today’s fibre optics. Traditionally in the analogue world, sending an audio signal from one device to another requires cables capable of transporting the voltage differentiation of a transduced signal. Consisting of one physical line of one way traffic from each source to their respective destinations. In the digital networking domain, the same is true but signals are transcoded into a binary format, which is then wrapped in a codex protocol. Allowing multiple channels of data to not only be sent down the same line but generally, a line of smaller size, substituting the use of bulky multicores with one or two low profile data cables. Basics of networking There are now several AoIP’s (Audio over Internet protocol) available, each provides a different service depending upon
the application for different infrastructure and bandwidth requirements. It is therefore important to understand the nuances of each, ensuring we have appropriate networks before embarking on any AoIP deployment. Based on the French scientific network “Cyclades“, developed in the 1970s, a modern network is a group of devices that can communicate with each other. With each device acting as a node, inter-connected between network types. The underlying theoretical model for networking is the Open Systems Interconnection (OSI), developed by the International Organization for Standardization (ISO) that splits up the functions of network communication into seven layers. TCP/IP is also a layered protocol, with equivalent operation and function to the ISO model. Developed by the Department of Defence’s (DoD) Advanced Research Projects Agency (ARPA). Today, it is the main protocol used for all Internet operations. TCP/IP
OSI
Defines interface to user processes for communication and data transfer.
7 Application 6 Presentatio
n
n
Applicatio
Translates data between a networking service and an application. Managing communication sessions exchange of information between two nodes.
5 Session 4 Transport
Internet
Outlines reliable and sequential packet delivery of end-to-end message delivery.
3 Networ
Transport
Under the umbrella of IP internet protocol, it structures and manages a multi-node network.
k
2 Data link 1 Physical
Network
Utilises the MAC address with the transmission of data frames between two physically connected nodes. Depicts the transmission and reception of raw bit streams over physical medium between devices.
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