# Interconnecting Haptic Interfaces with High Update Rates through the Internet +
## 3 The Network Conditions of the Internet  
A lot of research [44; 45; 46] has been conducted for the network conditions of the Internet. Network conditions refer to the amount of traffic that is being transferred through the Internet, the End to End delay, as well as the jitter between source and destination, and the available bandwidth for data transport. The results from research [3; 4; 5; 6] have concluded that in order to maximize the Quality of Experience (QoE) of the user for haptic streams, the network conditions should satisfy the Quality of Service (QoS) requirements of Table 1.  
All the above metrics vary in time and space. They depend on the number of online users, the amount of data that is being transferred at the specific moment of the measurement, and the available equipment of lines and routers. It has been recorded that the amount of data transferred through the web is constantly increasing [47]. Apart from that, the number of online users is increasing as well. The growth of data transfer is compensated by continuing infrastructure upgrades of computer networks. There are two methods for measuring the network performance. The one is the active and the other is the passive method [44]. As far as the active monitoring is concerned, ICMP packets are sent over the network to monitor the delay, the round trip time, the jitter and the packet loss. Other active monitoring tools for network performance are the ping tool, the traceroute, the capprobe, the dummynet, the netem and the pathchar [45]. The passive method observes the network traffic using some tools that are called sniffers. The most known of them are the Tcpdump, the Wireshark, the Ethereal, the Netflow and the JFlow [44]. In order to monitor the network status, the authors actively measured the average and the standard deviation of the delay, the packet loss rate, and the number of hops of networks between countries and continents. Measurements for the above metrics were made by the authors between Japan and Korea, and between Japan and Greece [48]. A recent measurement has also been made between two cities of Greece, Grevena and Thessaloniki [49]. The distance between those two cities is 175 Km. Two different networks were used for this measurement, the private optical network, GRNET [50], part of the pan-European GEANT network with speeds up to 4 \(\times\) 10 Gbps, on the one hand and one simple 8 Mbps Adsl connection on the other. The results of these measurements are shown in Tables 2 and 3. For the above experiments, 3000 ICMP packets for each of 0, 6, 11, 15 and 19 o' clock standard time were sent from one destination to the other. It is understood that the Internet connection between Japan and Korea satisfy all the restrictions of Table 1 for transferring haptic data through the Internet. For the Internet connection between Japan and Greece, the values of Table 2 are relatively high because they refer to intercontinental pings. \begin{table}
\begin{tabular}{c c c c c} \hline
**QoS** & **Haptics** & **Video** & **Audio** & **Graphics** \\ \hline Jitter (ms) & \(\leq\)2 & \(\leq\)30 & \(\leq\)30 & \(\leq\)30 \\ \hline Delay (ms) & \(\leq\)50 & \(\leq\)400 & \(\leq\)150 & \(\leq\)100-300 \\ \hline Packet Loss (\%) & \(\leq\)10 & \(\leq\)1 & \(\leq\)1 & \(\leq\)10 \\ \hline Update Rate (Hz) & \(\geq\)1000 & \(\geq\)30 & \(\geq\)50 & \(\geq\)30 \\ \hline Packet Size (bytes) & 64–128 & \(\leq\)MTU & 160–320 & 192–5000 \\ \hline Throughput(kbps) & 512–1024 & 25,000–40,000 & 64–128 & 45–1200 \\ \hline \end{tabular}
\end{table} 
Table 1: QoS requirements for supermedia streams [3; 4; 5; 6; 7]. \begin{table}
\begin{tabular}{c c c c c} \hline
**Countries Connected** & **Avg. Delay (ms)** &
\begin{tabular}{c} **Standard Delay** \\ **Deviation (ms)** \\ \end{tabular} & **Packet Loss (\%)** & **No. Hops** \\ \hline Japan–Korea & 27.01 & 0.19 & 0.02 & 11 \\ \hline Japan-Greece & 331.10 & 6.30 & 1.53 & 26 \\ \hline \end{tabular}
\end{table} 
Table 2: Internet status for intercontinental communication [48].