After obtaining all the AS Paths from all collectors to all networks we have to filter to get only the Chilean networks. This process is not as simple as doing a search on Chilean network list, it is also correct to announce subnetworks, i.e. a subset of the network that is owned.

For example if you have the network of Fig '200.24.0.0/16', you can announce this entire network, one or both subnetworks '200.24.0.0/17','200.24.128.0/17', or some of their multiple subnetworks, you can even announce a network and also its subnetworks, for example to announce two subnetworks to an Autonomous System and announce the network to other Autonomous Systems, to have some backup in case of some eventuality.

In the particular case of Chile, according to the LACNIC Whois Bulk, there are 6838 Chilean networks, but many of these networks are actually subsets of other networks in that list so we would count more than once each IP. What we use is a set of networks such that there is no intersection between them, i.e. not have any IP that belongs to both networks. Just 696 of these networks have no other network like Chilean supernetwork, i.e. there is 696 disjoint sets of IPs in Chile. These sets are studied in this work, grouped by the company they belong.

A network or subnetwork, is considered'announced', if it is visible from a collector. This definition was adopted as this is the only way to know whether a network is being published or not, is to see it from somewhere (See it on a route table). Note that if a network is announced that network is active, is being used for some purpose. However, if the network is not announced, the rest of the world can not contact it, which means that this network is not being used, or there is no way to get to it.

To know if the network is announced, you should consider if the network was announced, or if any of its subnetworks was announced, taking in this case into consideration the size of the subnetwork announced.

To measure visibility, we take all the announced networks (if a network was not announced is impossible to be visible), and we measure how much of each network is visible from each collection, i.e. if the collector has in his table routes across the network, or one or more of its subnets. If a collector do not have the network or any of the subnetworks, the collector does not know how to reach the network, and therefore this network is not visible to it.

This corresponds to the visibility of the collection network to calculate the total network, visibility is averaged visibility collector.

To understand the concepts of announced and visibility, take as an example the following picture, in it there is a setting with three collectors, where green indicates that the network is present in the collector and the red represents that is not in its table. The collector 1 sees one of the two subnetworks, the collector 2 sees the other subnetwork, and in the collector there is no block present. Since the two subnetworks are present in a collector, the announced percentage is 100%.

From the announced percentage (the complete network), the collector 1 has only a subnetwork, which represents 50% of the total, so does the collector 2, then both have a 50% visibility, while the collector 3 has a visibility of 0%. The total network visibility is calculated as average of the visibilities and collector, in this case would be:

On the other hand in the figure below, on the collector tables 1 and 2 we see the same subnetwork, while the collector 3 does not see any of the subnetworks. In this scenario, we have that the network announced percentage is 50% and collector 1 and collector 2 have 100% visibility, they have 100% of the published network, the collector 3 has 0% visibility.

Then the total network visibility is:

In this way we get two values: the percentage of the network announced, and percentage of the network announced that it is visible from each collector. The visibility value should be always 100%, i.e., everything that we announce must be visible from all over the world.