Studying the Internet its structure is usually divided into levels: Autonomous Systems Level (AS), Point of Presence Level (PoP), Router Level, etc. The global network can be represented on each of them as a graph based on the initial data obtained from open sources. Consideration of a network within the framework of a separate level facilitates analysis, but does not allow to systematically assess its structural properties when providing the connectivity between several segments of the network related, particularly, to the objects of critical information infrastructure. To overcome this contradiction, a mathematical model of the global network in the form of a metagraph was developed at the interface between AS-level and PoP-level that takes into account the characteristics of each level and allows to find bottlenecks both in the interdomain routing system and in the topology of internal networks of Internet providers.
Based on the proposed model some structural phenomena of the global network are described: stub, multihomed and transit autonomous systems, content providers. Taking into account available data from open sources about Internet structure, a method for constructing a metagraph is proposed. A comparative analysis of tools that automate the process of analyzing a network model is carried out. The practice-oriented problems of finding a cutting subset in a metagraph were set. Certain areas of further research are software implementation of the models using module MGtoolkit in Python and the assessment of structural phenomena of Russian segments of the Internet.
Mathematical model of the spread of coronavirus infection COVID-19 with software implementation