Where is My next Hop? The case of Indian Ocean Islands

Internet is fundamental to our society as it provides important services ranging from safety and security services to entertainment. Internet was not designed originally to carry application data without time constraint and unlimited user interactions, as Internet performance is usually bound, inter alia, by physical factors such as distance, medium of transmission and link congestion. However, most of the applications used on the Internet today are delay-sensitive (for e.g. live streaming or online gaming). Having timely content delivery is therefore critical. However, as shown by the measurement performed from our study, all countries or regions are not equal from the Internet access and performance point of view.

It is known that the Indian Ocean Area (IOA), including Madagascar (MG), Mauritius (MU), Reunion Island (RE), Seychelles (SC) and Mayotte (YT) suffers from a poorly meshed Internet topology between themselves. Network performance between the islands is very likely to exhibit low performance and high delay characteristics, although the islands are physically connected to each other, there is no direct logical links between them. Many connections would therefore follow inter-continental circuitous routes before reaching neighbour islands, and in worst case scenarios, other networks in the same country. To improve interconnectivity in the IOA region, major investments in inter-island projects such as the Indian Ocean Commission’s METISS (MElting poT Indianoceanic Submarine System), the Africa-1 and IOX submarine cables. However, improved physical topology without proper peering and traffic exchange between network operators in the region would not necessarily improve the situation as shown in two of our recent studies on Reunion Island Internet connectivity and performance and on the impact of long delays on TCP performance. We pointed out why it is important to break the Internet silo in this region to improve Internet access. They performed measurements on the outbound connectivity of the Indian Ocean Islands to the rest of the world.

The following map shows that each Island is connected to the Internet with one or more submarines cable.

Figure  SEQ Illustration \* ARABIC 1: Indian Ocean Islands submarine cable

Measurement study

Using a Raspberry-Pi, Paris-Traceroute and rTraceroute, we analyzed 4,480,000 traces between IOA and destinations spread around the world. The selection of the destination was based on a random generation of IP addresses. This set was tested by ICMP protocol and geolocalised by RIPE NCC API.

The first step before any analysis was to clean the data set. We remove traces that met one of the following criteria :

• The destination have not been reached;
• A 3 following stars are present at the end of the trace ;
• The presence of ‘!N’ (Network Unreachable) or ‘!H’ (Host Unreachable) marks due to Paris-Traceroute ;
• Some corrupted trace (exception probe, empty traces,…) ;
• Presence of loops (255 hops reached) ;
• The presence of IP whose countries are not present in the RIPE NCC database. The IP address 100.41.0.15 is an example.

After data filtering, we obtained 1,053,894 clean traceroute traces.

Results

The Figure 2 plot the number of exit point for each IOA island. We count the first hop outside each Island. 

Figure  SEQ Illustration \* ARABIC 2: Number of Internet output links from each countries from IOA.

This figure shows that each island has at least 20 exit points (except for Mayotte which have only one exit point). This figure seems to indicate some path diversity for the Internet traffic of each Island. In Table I, the details of the exit point of each country are given.

Table 1 : Table of exit point from IOA

Other included all countries which percent are less than 1%. This table confirms the diversity of the exit points. It also shows that for most islands in the IOA more than 90% of the traffic exits through three main countries. Table 1 shows some asymmetrical behavior in routing and peering policies. For example, Mauritius (MU) appears in Seychelles’s (SC) exit point but Seychelles does not appear in Mauritius.

Conclusion

Studying path and routing is a very important task in regions where the Internet access is not very fairly distributed, as it is the case for Indian Ocean islands. The major result indicates that most of the Islands are world-connected, but with a poor regional peering and meshing. It seems that the IXP and regional peering are not really optimised / well-configured or actually nonexistent.

About the Author

Réhan Noordally, is a PhD Student at Reunion Island University currently working on Internet measurement and TCP performance for Reunion island and Indian Ocean Area.