An Investigation into Transport Protocols and Data Transport ...

3.1. Data Intercommunication 41
movement of data to be processed, there would be very little point in having
a distributed Grid.
Fortunately, with the standardisation of the Internet [IET], much work
has already been done to enable seamless transfer of data from one system
to another. In this section, the paradigm of data transfer across the Internet
are discussed and the performance of the various layers that enable data
inter-communication are investigated.
TCP/IP
The TCP/IP protocol suite is commonly used by all modern operating systems.
TCP/IP [Ste94] is designed around a simple four-layer scheme. The
four network layers defined by the TCP/IP model are as follows.
Layer 1 - Link This layer defines the network hardware and device drivers
that refer to the physical and data link layers of OSI [Tan96].
Layer 2 - Network This layer is used for basic communication, addressing
and routing. TCP/IP uses IP and ICMP protocols at the network layer
and encompasses the network layer of OSI.
Layer 3 - Transport Handles communication among programs on a network.
TCP and UDP falls within this layer and hence is also equivalent
to the transport layer in OSI.
Layer 4 - Application End-user applications reside at this layer and represents
the remaining layers of OSI: the session, presentation and application
layers.
There are two main transport protocols that are commonly used today:
User Datagram Protocol (UDP) [Pos80] and Transmission Control Protocol