Virtual vpn in the cloud

6.2
 
Measuring metrics
Since dealing with VPNs introduces additional IP headers and complex processing of 
cryptographic operations, the overhead introduced during data transmission has been studied. 
Measuring the link throughput gives details on network performance, which can be further 
studied and analyzed with the number of packets lost during transmission and with the delay 
encountered.
Network throughput is defined as the rate at which data is transmitted over a 
communication channel. In addition to providing secure data over dedicated links, reliability 
of the established connection channel is also equally important for simulating a direct 
connection. The reliability of the network depends largely on the throughput of data in the 
connection. Hence to ensure secure and reliable transfer of data, throughput is taken as one 
for important parametric analyses. 
Jitter is defined as the inter-arrival time variation between packets to their destination. 
Good transmission network record jitter values between 1 to 5 milliseconds [46]. Low jitter 
values help in maintaining the inter-packet delay introduced by the source, which is of 
utmost importance when dealing with small sized packets.
Packet loss takes place when packets travelling across a channel fail to reach their 
destination network. To ensure good link quality, packet loss of the network is maintained 
below 1% in this research [45]. Higher the loss of packets in the network, greater will be the 
TCP segment retransmissions, ultimately affecting available network bandwidth [35]. 
VM resource allocation metrics involving VM start up time, VM service start up time 
and VM Failure Ratio are measured and evaluated to determine reliability and speed of 
orchestration management. 
6.2.1
 
Cryptographic Analysis 
Taking into account the different combinations of encryption and hashing algorithms, 
it is observed that AES128-MD5 outperforms in all the cases