Towards capturing representative AS-level Internet topologies

Abstract

Abstract-Recent studies concerning the Internet connectivity at the AS level have attracted considerable attention. These studies have exclusively relied on the BGP data from Oregon route-views [1] to derive some unexpected and intriguing results. The Oregon route-views data sets reflect AS peering relationships, as reported by BGP, seen from a handful of vantage points in the global Internet. The possibility that these data sets from Oregon route-views may provide only a very sketchy picture of the complete inter-AS connections that exist in the actual Internet has received surprisingly little scrutiny. In this paper, we will use the term "AS peering relationship" to mean that there is "at least one direct router-level connection" between two existing ASs, and that these two ASs agree to exchange traffic by enabling BGP between them. By augmenting the Oregon route-views data sets with BGP summary information from a large number of Internet Looking Glass sites and with routing policy information from Internet Routing Registry (IRR) databases, we find that (1) a significant number of existing AS connections remain hidden from most BGP routing tables, (2) the AS connections to tier-1 ASs are in general more easily observed than those to non tier-1 ASs, and (3) there are at least about 25-50% more AS connections in the Internet than commonly-used BGP-derived AS maps reveal (but only about 2% more ASs). These findings point out the need for an increased awareness of and a more critical attitude toward the applicability and completeness of given data sets at hand when establishing the generality of any particular observations about the Internet.

Acyclic Type of Relationships Between Autonomous Systems

“…Moreover, we found out using the algorithm presented in [13] (and similar to the results presented in [13] over older data), that the simpler 0-ToR problem (i.e. regardless the existence of cycles), does not have a valley-free solution as well 8 . Next, we execute the different algorithms over the entire Route-Views database.…”

“…If the orientation of an edge, assigned by a specific algorithm is different from the actual orientation of the edge, it means that there is a mismatch between the export policy inferred by the algorithm to the actual export policy of one 8 We refer to the 0-ToR problem as the decision version of the ToR problem that determines if there is a solution without any invalid path. Type I Type II provider-customer Type II Type I peer-peer Type I Type I sibling-sibling Type II Type II TABLE I EXPORT POLICY AND TYPE OF RELATIONSHIP or both nodes.…”

“…Nevertheless, using the IRR database to infer the hierarchical structure of the AS connectivity map has several drawbacks. First, in some cases, entries in the IRR may be invalid and contain out-of-date data [8]. Second, this database is not complete enough.…”

NIT: A New Internet Topology Generator

“…The collection and gathering of data related to the AS level topology have been the subject of a intense debate in the community [3,11,12,13,14,15]. As a consequence, more complete databases have been constructed.…”

Inter-domain QoS routing on Diffserv networks: a region-based approach

“…One important issue we have to point out with this suggestion is the possibility of the incompleteness of topologies generated by using these routing tables. Authors in [15] studied the topologies generated using Oregon Route Views BGP data and compared that with topologies they constructed using the data they collected employing several different Looking Glass sites and Internet Routing Registry (IRR). As a result of the study, authors found out that "there are at least about 25%-50% more AS connections in the Internet than commonly-used BGP-derived AS maps reveal".…”