The Internet: A System of Interconnected Autonomous Systems Mehmet Engin Tozal

The Internet The Internet A global system of interconnected networks Has already become a de-facto utility Communication & Entertainment Marketing & Administration Collaboration & Citizen participation Highly engineered Globally distributed Large scale complex system Studying the structure of the Internet helps us to Gain more insight into its topological features Understand its operational characteristics Enhance its communication infrastructure Improve its reliability, resiliency and security

Autonomous Systems Autonomous System (AS) A group of networks under a well defined protocol Identified by unique AS number Connected to each other through business relations Customer-to-Provider (c2p) Peer-to-Peer (p2p) Sibling-to-Sibling (s2s) The traffic in the Internet is routed according to the business relations among ASes

Autonomous Systems Example AS-level Internet topology map

Autonomous Systems Taxonomy of ASes in the Internet Stub, Tier-1, Tier-2, Tier-3, Transit, … Ambiguous Subjective Unrealistic Pole, Axial, Medial, Locus Terminology from Geometry Clear Objective Realistic Traditionally the ASes are classified as …

Autonomous Systems Taxonomy of ASes in the Internet

AS Analysis - Preliminaries

AS Analysis – Axial ASes ClusterA: governments and government-related organizations ClusterB: large scale IXPs and datacenters ClusterC: small sized IXPs or ISPs that provide value-added services ClusterD: pole ASes enabling global connectivity

AS Analysis – Medial ASes The orbit of a medial AS is the length of the shortest c2p path(s) to any pole AS O1 44% O2 50% O3,4 6% O5 1 AS

AS Analysis – Medial ASes Medial AS customers, providers and peers by orbits Diversity in distributions Kruskal-Wallis rank sum tests verify the differences in distributions by orbits Mean and variability decrease as orbit increases By using Kruskal-Wallis rank sum test we can decide whether the population distributions are identical without assuming them to follow the normal distribution

AS Analysis – Medial ASes Medial ASes average peer links by country (top 25% ~ 92%) Peering as a networking practice adopted at developed countries

AS Analysis – Locus ASes Average hops to a pole AS via c2p links is 1.91 26% single hop 57% two hops 15% three hops 2% four/five hops A shorter distance implies a better average performance

AS Analysis – Locus ASes Locus ASes average distance to the pole ASes by country (top 25% ~ 94%) Shorter distance implies better performance, on the average

Questions Thank you!

Agenda The Internet Autonomous Systems (ASes) AS Analysis – Preliminaries AS Analysis – Axial ASes AS Analysis – Pole Ases AS Analysis – Medial Ases AS Analysis – Locus ASes

AS Analysis - Preliminaries AS-Relations Dataset (CAIDA) Business relations Oregon routeviews project AS-Organizations Dataset (CIDR-Report) Organization information AS-to-country mappings Large scale ISPs operate at multiple countries

AS Analysis – Pole ASes