BGP Routing Dynamics Revisited

By: 
Jun Li, Michael Guidero, Zhen Wu, Eric Purpus, and Toby Ehrenkranz
Appears in: 
CCR April 2007

Understanding BGP routing dynamics is critical to the solid growth and maintenance of the Internet routing infrastructure. However, while the most extensive study on BGP dynamics is nearly a decade old, many factors that could affect BGP dynamics have changed considerably. We revisit this important topic in this paper, focusing on not only comparing with the previous results, but also issues not well explored before. We have found that, compared to almost a decade ago, although certain characteristics remain unchanged (such as some temporal properties), BGP dynamics are now “busier,” and more importantly, now have much less pathological behavior and are “healthier”; for example, forwarding dynamics are now not only dominant, but also more consistent across different days. Contributions to BGP dynamics by different BGP peers—which are not proportional to the size of a peer’s AS—are also more stable, and dynamics due to policy changes or duplicate announcements are usually from specific peers.

Public Review By: 
Serge Fdida

BGP is indeed a critical protocol of the Internet. Understanding its behaviour, robustness and dynamics is therefore of utmost importance. This paper proposes an update of our knowledge in this area with respect to the comprehensive work by Labowitz et al (Sigcomm'97). The authors use recent BGP data from RIPE and pay particular attention to the changes in Internet routing dynamics since Labovitz work. Deriving observations from measurements is an important work if properly done.
The paper is concerned by producing an analysis as in Labovitz, using a similar methodology and taxonomy in order to be able to benchmark the current BGP with respect to the observations carried out 10 years ago. This is a general concern in any area to be able to derive observations of a system over time, develop its analysis and build an understanding of the causes that produce the observations.
The main founding of this paper is that, a decade later, BGP dynamics are now “busier” but “healthier.”
Others informative results are derived and provide an interesting update on the subject though many other studies of BGP were published since 97.
Nevertheless, comparing dynamic systems over a ten year period is not obvious as the original classification needs to be deepened and extended: to extract a better knowledge about the system dynamics, and to observe new behaviours.
This paper has therefore been considered as valuable for the networking community. It presents a snapshot of the current BGP dynamics, discusses its evolution with respect to the work by Labovitz and, indirectly, questions the issue of the methodology to observe the same dynamic system over time and understand the causes behind the dynamics.