# Implementation and Evaluation of HTTP/3 Connectivity Check Using Happy Eyeballs Algorithm
## 5 Discussion  
In the environment without delays or losses, the time that was required to establish a connection was slightly longer for HTTP/3, but HTTP/3 had a higher probability of being adopted. The reason for the slight reversal in the connection establishment time \begin{table}
\begin{tabular}{c c c c} \hline
**Delay (ms)** & **Adoption Rate (\%)** & **Avg. Time (ms)** & \(\sigma\) **(ms)** \\ \hline
0 & 99.7 & 3.2 & 1.4 \\
50 & 100.0 & 57.4 & 4.4 \\
100 & 100.0 & 108.2 & 2.7 \\
150 & 100.0 & 158.4 & 2.8 \\
200 & 100.0 & 208.4 & 4.6 \\ \hline \end{tabular}
\end{table} 
Table 1: HTTP/3 adoption rate and connection establishment time with external delay settings. (Happy Eyeballs). \begin{table}
\begin{tabular}{c c c c} \hline
**Loss Rate (\%)** & **Avg. Time (ms)** & \(\sigma\) **(ms)** & **Max. Time (ms)** \\ \hline
0 & 99.7 & 3.2 & 1.4 \\
3 & 96.4 & 4.8 & 32.4 & 1005 \\
10 & 91.0 & 18.5 & 110.2 & 1079 \\
25 & 78.0 & 79.3 & 278.0 & 3115 \\
50 & 62.7 & 474.0 & 975.0 & 15,475 \\ \hline \end{tabular}
\end{table} 
Table 3: HTTP/3 adoption rate and connection establishment time with packet loss settings. (Happy Eyeballs). \begin{table}
\begin{tabular}{c c c c} \hline
**Delay (ms)** & **Adoption Rate (\%)** & **Avg. Time (ms)** & \(\sigma\) **(ms)** \\ \hline
0 & 99.7 & 3.2 & 1.4 \\
50 & 100.0 & 57.4 & 4.4 \\
100 & 100.0 & 108.2 & 2.7 \\
150 & 100.0 & 158.4 & 2.8 \\
200 & 100.0 & 208.4 & 4.6 \\ \hline \end{tabular}
\end{table} 
Table 2: HTTP/3 adoption rate and connection establishment time with external delay settings. (Alt-Svc). \begin{table}
\begin{tabular}{c c c c} \hline
**Loss Rate (\%)** & **Avg. Time (ms)** & \(\sigma\) **(ms)** & **Max. Time (ms)** \\ \hline
0 & 2.1 & 0.8 & 18 \\
3 & 36.8 & 173.1 & 1073 \\
10 & 120.6 & 310.2 & 3079 \\
25 & 374.0 & 675.9 & 7125 \\ \hline \end{tabular}
\end{table} 
Table 4: HTTP/3 adoption rate and connection establishment time with packet loss settings. (Alt-Svc). may be that the network distance was extremely close, and the difference in processing time by the computers was noticeable. Because the proposed method processes multiple communications asynchronously, the computational burden is somewhat greater than that in existing methods. However, situations in which such delays and losses do not exist rarely occur. Even if they do occur, selecting HTTP/3 and ignoring the average 1 ms difference in the connection initiation time cannot pose a problem. It can be observed from Table 1 that even if external delays were to occur, selecting the Happy Eyeballs protocol would have little impact. In contrast, when external delays of 50 ms or more occured, the difference in the connection establishment time between the proposed and existing methods was close to the external delay time that was imposed on a single round-trip communication. This is the difference that is created by the handshake duplicated by the old HTTP in the existing method. That is, this similarity can be interpreted as a confirmation of the theory of efficiency to which the proposed method appeals. In particular, of the two failure factors that were targeted in this study, the external delay mimics the distance in a normal real network. Hence, it is quite possible that traffic on the real Internet may follow the experimental results as a function of the distance. We now consider the behavior in environments in which packet loss occured, which was mentioned as another failure factor. It appears from Table 3 that the adoption rate of HTTP/3 by Happy Eyeballs monotonically decreased as the packet loss rate increased. However, theoretically, this trend is reasonable because HTTP/3 is highly effective in packet retransmissions once the connection is established. Moreover, because the existing method failed to measure availability below 99.9% when the packet loss rate reaches 50%, the proposed method, which succeeded in 1,000 connections out of 1,000 under the same conditions, could be sufficiently valuable.