US Robotics USR2410 Manual de usuario descargar pdf (Pagina 15)

Chapter 2 -

Background

This section will provide insight and background to the advanced topics discussed throughout the

report.

2.1

Network Layer Hierarchy

As this project deals largely with networking concepts, a discussion of the network hierarchy that

data passes through on computer systems needs to be discussed. The network TCP/IP hierarchy

can be broken down into four basic logical layers. These are, from top to bottom, the application

layer, the transport layer, the network layer and the physical or network interface layer as shown

in Figure 2-1. The relevant layers for this project were the transport, network and physical layers.

Figure 2-1: Network Hierarchy

The application layer is governed by the programs that generate the data. As this project is not

concerned with what applications are being run, this layer will not be discussed.

The transport layer deals with end-to-end data correctness. It is at this layer that data is

segmented into packets. Two important protocols at this layer are TCP and UDP. The TCP

protocol defines a series of handshaking steps needed to create a connection, and maintains a

stable connection by retransmitting dropped packets. The UDP protocol is a best-effort

connectionless protocol. It provides no mechanism to establish a connection, or retransmit

dropped packets.

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US Robotics USR2410 Manual de usuario Pagina 15