Comments on bufferbloat

By: Mark Allman

Appears in: CCR January 2013

Abstract: While there has been much buzz in the community about the large depth of queues throughout the Internet—the socalled “bufferbloat” problem—there has been little empirical understanding of the scope of the phenomenon. Yet, the supposed problem is being used as input to engineering decisions about the evolution of protocols. While we know from wide scale measurements that bufferbloat can happen, we have no empirically-based understanding of how often bufferbloat does happen. In this paper we use passive measurements to assess the bufferbloat phenomena.

Public Review By: Nikolaos Laoutaris

The large buffers found in devices across the Internet---the so-called "bufferbloat" problem---has been discussed anecdotally for quite some time. Still, as of now we seem to lack any systematic study shedding light into the scope and frequency of the phenomenon. This paper presents a first such quantification attempt. The analysis is decomposed in two categories: evaluating the prevalence of the phenomenon and then its impact on the initial window of TCP, based on traffic collected from a FTTH deployment attached to a university, as well some laboratory data. The preliminary findings of the empiric study is that while buffer bloat exists, the magnitude of the phenomenon seems to be quite modest, with little or no proof of large scale persistent queues. The authors note that although their findings are not conclusive, they raise a useful question on the true extent of the bufferbloat problem. All reviewers have agreed to that. Initially bufferbloat was thought to be largely a residential broadband network problem (in the upload direction in particular). While the bufferbloat community later began to suspect it was "everywhere," the most likely source of bufferbloat remained the residential broadband networks (and in particular the upload link). The reviewers note that the "residential" network studied in the paper is not likely representative of such networks. They recommend further analysis based on "more typical" residential broadband networks. A provocative "myth-busting" type of paper that can generate interesting and useful discussions.