11  Acknowledgements

Grateful acknowledgement is made to the following sources:

Figure 1: Cisco

Figure 2: Birmingham City University (BCU)

Figure 3: Birmingham City University (BCU)

Figure 4: Cisco

Figure 5: Birmingham City University (BCU)

Figure 6: Cisco

Figure 7: Birmingham City University (BCU)

Figure 10: Birmingham City University (BCU)

Figure 11: Birmingham City University (BCU)

Figure 12: Birmingham City University (BCU)

Figure 13: Birmingham City University (BCU)

Figure 14: Birmingham City University (BCU)

Figure 15: Birmingham City University (BCU)

Figure 16: Birmingham City University (BCU)

Figure 17: Birmingham City University (BCU)

Every effort has been made to contact copyright holders. If any have been inadvertently overlooked the publishers will be pleased to make the necessary arrangements at the first opportunity.