The impact of Internet policy and topology on delayed routing convergence

Abstract

This paper examines the role inter-domain topology and routing policy play in the process of delayed Internet routing convergence. In recent work, we showed that the Internet lacks effective inter-domain path fail-over. Unlike circuit-switched networks which exhibit fail-over on the order of milliseconds, we found Internet backbone routers may take tens of minutes to reach a consistent view of the network topology after a fault. In this paper, we expand on our earlier work by exploring the impact of specific Internet provider policies and topologies on the speed of routing convergence. Based on data from the experimental injection and measurement of several hundred thousand inter-domain routing faults, we show that the time for end-to-end Internet convergence depends on the length of the longest possible backup autonomous system path between a source and destination node. We also demonstrate significant variation in the convergence behaviors of Internet service providers, with the larger providers exhibiting the fastest convergence latencies. Finally, we discuss possible modifications to BGP and provider routing policies which if deployed, would improve interdomain routing convergence.

Misleading stars: what cannot be measured in the internet?

“…In the current Internet, policy routing is known to have in impact both on the route length [15] and on the convergence time [12]. AXIOM 2 (α-(Routing) Consistency): There exists an α ∈ (0, 1] such that, for every trace T ∈ T , if d T (σ 1 , σ 2 ) = k for two entries σ 1 , σ 2 in trace T , then the shortest path connecting the two (named or anonymous) nodes corresponding to σ 1 and σ 2 in G 0 has distance at least αk .…”

Link-Level Network Topology Generation

“…These studies shifted the attention to degree based generators. In order to bridge the gap between the local and the global properties of the Internet, statistical physics based approaches are proposed [11], [26], [27]. Since in most real-world networks new edges are not placed randomly but have a tendency to connect to high degree nodes, preferential attachment paradigm has been introduced [28].…”

“…Generation of realistic Internet topologies is an important research problem [9], [10]. This understanding is especially important for newly developed protocols as the performance of protocols highly depend on the topological features of the Internet [11], [12], [13]. A protocol may perform very eff ciently on a model, but run quite poorly when deployed on the Internet.…”

The extent of AS path inflation by routing policies

“…For example, in Figure 9, AS paths (2,3,4) and (2,6,3,4) are no-valley paths, and AS2 will prefer the AS path (2,3,4) via customer AS3 instead of peer AS6 to reach AS4.…”

“…First, since ISPs typically do not make their routing policies public, it is not clear how prevalent these routing policies are and to what extent AS paths are inflated due to routing policies. Second, BGP protocol studies [5], [6] have shown that BGP convergence speed is directly correlated with AS path length. The extent of AS path inflation indicates the extent to which routing policies can increase BGP convergence time.…”