The Two Contending Network Layer Schemes
So, how to design and implement the complex responsibilities of the
Network Layer?
One community (the telecommunications companies)
believe that all data should be
transmitted reliably by the Network Layer.
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Their proposal is for a connection-based service,
termed a virtual circuit,
in which :
- Before sending data,
the Transport Layer should establish a
'semi-permanent' connection between the source and destination.
- The two Transport Layers then agree (argue)
about the type and quality of service (QoS)
that is required and will be available.
- Communication then occurs between the two parties in a duplex
fashion along the acquired connection.
- The connection is then closed by both parties.
- Each routing device maintains tables of pairs of source and virtual
circuit numbers and
destination and virtual circuit numbers.
The analogy here is with a telephone conversation.
The connection-based service is often called a session-based service.
See also: GettyImages: telephone switchboard operator
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CITS3002 Computer Networks, Lecture 5, The Network Layer, p7, 25th March 2024.
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CITS3002