Tag Archives: scientific

Exploring Domain Name Based Features on the Effectiveness of DNS Caching

Shuai Hao, Haining Wang.
Abstract

Software-defined networking (SDN) is a well-known example of a
research idea that has been reduced to practice in numerous settings.
Network virtualization has been successfully developed commercially
using SDN techniques. This paper describes our experience in
developing production-ready, multi-vendor implementations of a complex
network virtualization system. Having struggled with a traditional
network protocol approach (based on OpenFlow) to achieving interoperability among
vendors, we adopted a new approach. We focused first on
defining the control information content and then used a generic
database protocol to synchronize state between the elements. Within
less than nine months of starting the design, we had achieved basic
interoperability between our network virtualization controller and the
hardware switches of six vendors. This was a qualitative improvement on
our decidedly mixed experience using OpenFlow. We found a
number of benefits to the database approach, such as speed of
implementation, greater hardware diversity, the ability to abstract
away implementation details of the hardware, clarified state
consistency model, and extensibility of the overall system.

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On the Potential Abuse of IGMP

Matthew Sargent, John Kristoff, Vern Paxson, Mark Allman.
Abstract

Software-defined networking (SDN) is a well-known example of a
research idea that has been reduced to practice in numerous settings.
Network virtualization has been successfully developed commercially
using SDN techniques. This paper describes our experience in
developing production-ready, multi-vendor implementations of a complex
network virtualization system. Having struggled with a traditional
network protocol approach (based on OpenFlow) to achieving interoperability among
vendors, we adopted a new approach. We focused first on
defining the control information content and then used a generic
database protocol to synchronize state between the elements. Within
less than nine months of starting the design, we had achieved basic
interoperability between our network virtualization controller and the
hardware switches of six vendors. This was a qualitative improvement on
our decidedly mixed experience using OpenFlow. We found a
number of benefits to the database approach, such as speed of
implementation, greater hardware diversity, the ability to abstract
away implementation details of the hardware, clarified state
consistency model, and extensibility of the overall system.

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A Database Approach to SDN Control Plane Design

Bruce Davie, Teemu Koponen, Justin Pettit, Ben Pfaff, Martin Casado, Natasha Gude, Amar Padmanabhan, Tim Petty, Kenneth Duda, Anupam Chanda.
Abstract

Software-defined networking (SDN) is a well-known example of a
research idea that has been reduced to practice in numerous settings.
Network virtualization has been successfully developed commercially
using SDN techniques. This paper describes our experience in
developing production-ready, multi-vendor implementations of a complex
network virtualization system. Having struggled with a traditional
network protocol approach (based on OpenFlow) to achieving interoperability among
vendors, we adopted a new approach. We focused first on
defining the control information content and then used a generic
database protocol to synchronize state between the elements. Within
less than nine months of starting the design, we had achieved basic
interoperability between our network virtualization controller and the
hardware switches of six vendors. This was a qualitative improvement on
our decidedly mixed experience using OpenFlow. We found a
number of benefits to the database approach, such as speed of
implementation, greater hardware diversity, the ability to abstract
away implementation details of the hardware, clarified state
consistency model, and extensibility of the overall system.

Download the full article

Towards a Context-Aware Forwarding Plane in Named Data Networking supporting QoS

Daniel Posch, Benjamin Rainer, Hermann Hellwagner.
Abstract

The emergence of Information-Centric Networking (ICN) provides considerable opportunities for context-aware data distribution in the network’s forwarding plane. While packet forwarding in classical IP-based networks is basically predetermined by routing, ICN foresees an adaptive forwarding plane considering the requirements of network applications. As research in this area is still at an early stage, most of the work so far focused on providing the basic functionality, rather than on considering the available context information to improve Quality of Service (QoS). This article investigates to which extent existing forwarding strategies take account of the available context information and can therefore increase service quality. The article examines a typical scenario encompassing different user applications (Voice over IP, video streaming, and classical data transfer) with varying demands (context), and evaluates how well the applications’ requirements are met by the existing strategies.

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CliMB: Enabling Network Function Composition with Click Middleboxes

Rafael Laufer, Massimo Gallo, Diego Perino, Anandatirtha Nandugudi.
Abstract

Click has significant advantages for middlebox development, including modularity, extensibility, and reprogrammability. Despite these features, Click still has no native TCP support and only uses nonblocking I/O, preventing its applicability to middleboxes that require access to application data and blocking I/O. In this paper, we attempt to bridge this gap by introducing Click middleboxes (CliMB). CliMB provides a full-fledged modular TCP layer supporting TCP options, congestion control, both blocking and nonblocking I/O, as well as socket and zero-copy APIs to applications. As a result, any TCP network function may now be realized in Click using a modular L2-L7 design. As proof of concept, we develop a zero-copy SOCKS proxy using CliMB that shows up to 4x gains compared to an equivalent implementation using the Linux in-kernel network stack.

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Latency Measurement as a Virtualized Network Function using Metherxis

Diego Rossi Mafioletti , Alextian Bartholomeu Liberatto , Rodolfo da Silva Villaça, Cristina Klippel Dominicini, Magnos Martinello, Moises Renato Nunes Ribeiro.
Abstract

Network latency is critical to the success of many highspeed, low-latency applications. RFC 2544 discusses and defines a set of tests that can be used to describe the performance characteristics of a network device. However, most of the available measurement tools cannot perform all the tests as described in this standard. As a novel approach, this paper proposes Metherxis, a system that can be implemented on general purpose hardware and enables Virtualized Network Functions (VNFs) to measure network device latency with micro-second grade accuracy. Results show that Metherxis achieves highly accurate latency measurements when compared to OFLOPS, a well known measurement tool.

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Measuring the Quality of Experience of Web users

Enrico Bocchi, Luca De Cicco , Dario Rossi.
Abstract

Measuring quality of Web users experience (WebQoE) faces the following trade-off. On the one hand, current practice is to resort to metrics, such as the document completion time (onLoad), that are simple to measure though knowingly inaccurate. On the other hand, there are metrics, like Google’s SpeedIndex, that are better correlated with the actual user experience, but are quite complex to evaluate and, as such, relegated to lab experiments. In this paper, we first provide a comprehensive state of the art on the metrics and tools available for WebQoE assessment. We then apply these metrics to a representative dataset (the Alexa top-100 webpages) to better illustrate their similarities, differences, advantages, and limitations. We next introduce novel metrics, inspired by Google’s SpeedIndex, that offer significant advantage in terms of computational complexity, while maintaining a high correlation with the SpeedIndex. These properties make our proposed metrics highly relevant and of practical use.

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Recursive SDN for Carrier Networks

James McCauley, Zhi Liu, Aurojit Panda, Teemu Koponen, Barath Raghavan, Jennifer Rexford, Scott Shenker.
Abstract

Control planes for global carrier networks should be programmable and scalable. Neither traditional control planes nor new SDN-based control planes meet both of these goals. Here we propose a framework for recursive routing computations that combines the best of SDN (programmability through centralized controllers) and traditional networks (scalability through hierarchy) to achieve these two desired properties. Through simulation on graphs of up to 10,000 nodes, we evaluate our design’s ability to support a variety of unicast routing and traffic engineering solutions, while incorporating a fast failure recovery mechanism based on network virtualization.

Public review by Joseph Camp

While software-defined networks have received significant attention in recent years, the networks studied often lack multiple orders of magnitude from today’s global carrier networks in terms of geographical span and nodal scale. Hence, this paper sets forth a recursive routing computation framework that balances the programmability of SDNs with the scalability of a traditional hierarchical structure. Simulations of about 10,000 nodes are used to show the viability of such an approach. Remarkably, the authors show that their recovery approach can offer “five 9s” of network repair even under a heavy link failure scenario.

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Controlling Queuing Delays for Real-Time Communication: The Interplay of E2E and AQM Algorithms

Gaetano Carlucci, Luca De Cicco, Saverio Mascolo.
Abstract

Real-time media communication requires not only congestion control, but also minimization of queuing delays to provide interactivity. In this work we consider the case of real-time communication between web browsers (WebRTC) and we focus on the interplay of an end-to-end delay-based congestion control algorithm, i.e. the Google congestion control (GCC), with two delay-based AQM algorithms, namely CoDel and PIE, and two flow queuing schedulers, i.e. SFQ and Fq_Codel. Experimental investigations show that, when only GCC flows are considered, the end-to-end algorithm is able to contain queuing delays without AQMs. Moreover the interplay of GCC flows with PIE or CoDel leads to higher packet losses with respect to the case of a DropTail queue. In the presence of concurrent TCP traffic, PIE and CoDel reduce the queuing delays with respect to DropTail at the cost of increased packet losses. In this scenario flow queuing schedulers offer a better solution.

testbed

Public review by Fabian Bustamante

For an increasingly important class of Internet applications – such as videoconference and personalized live streaming – high delay, rather than limited bandwidth, is the main obstacle to improved performance. A common problem that impacts this class of applications is “bufferbloat”, where excess buffering in the network causes high latency and jitter. Solutions for persistently full buffer problems, active queue management (AQM) schemes such as the original RED, have been known for two decades. Yet, while RED is simple and effective at reducing persistent queues is not widely or consistently configured and enabled in routers and sometimes directly unavailable.

Recent focus on bufferbloat has brought a number of new AQM proposals, including PIE and CoDel, which explicitly control the queuing delay and have no knobs for operators, users or implementers to adjust. This paper considers the interplay between some of these AQM protocols and the new end-to-end delay-based congestion control algorithm, Google Congestion Control (GCC) part of the WebRTC framework.

Two sets of reviewers agree that, while the topic is well established, there is still significant work to be done and the authors contribute and incremental yet valuable analysis in the context of real-time communication and the increasingly popular WebRTC. The authors were encouraged to release the software used for conducting their measurements to let other researchers in the community replicate their results and explore some of the variants and alternative scenarios raised by different reviewers.

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What do parrots and BGP routers have in common?

David Hauweele, Bruno Quoitin, Cristel Pelsser, Randy Bush.
Abstract

The Border Gateway Protocol propagates routing information accross the Internet in an incremental manner. It only advertises to its peers changes in routing. However, as early as 1998, observations have been made of BGP announcing the same route multiple times, causing router CPU load, memory usage and convergence time higher than expected.

In this paper, by performing controlled experiments, we pinpoint multiple causes of duplicates, ranging from the lack of full RIB-Outs to the discrete processing of update messages. To mitigate these duplicates, we insert a cache at the output of the routers. We test it on public BGP traces and discuss the relation of the cache performance with the existence of bursts of updates in the trace.

 

Public review by Alberto Dainotti

What do parrots and BGP routers have in common?

Nothing, of course.” — you might answer the question in this paper’s title.
Since parrots simply repeat the sounds they hear, with no understanding of their meaning“. On the contrary, BGP speakers process the messages they receive and, hopefully, understand them before talking. However, a careful check of literature, may (or may not) make you reconsider the question:

  • E. N. Colbert-White, M. A. Covington, D. M. Fragaszy,
    Social Context Influences the Vocalizations of a Home-Raised African Grey Parrot (Psittacus erithacus erithacus)
    Journal of Comparative Psychology, Online First Publication, March 7, 2011. doi: 10.1037/a0022097

Moving from the paper title to the content: the authors investigate the problem of redundant BGP update messages (duplicate updates) generated by BGP routers. This phenomenon would normally be prevented by the Adj-RIBs-Out, which “contains the routes for advertisement to specific peers by means of the local speaker’s UPDATE messages.” [RFC 4271]. However, the Adj-RIBs-Out is sometimes not fully implemented or disabled in order to save memory. Previous studies have shown that duplicates can reach percentages above 80% in busy times (showing similarity to parrots to a BGP peer) and be detrimental to operations by causing high CPU loads.

This study contributes to the problem in two ways: (i) it explains the origin of several types of duplicate occurrences; (ii) it demonstrates that a simple
cache, requiring less memory usage than the Adj-RIBs-Out, can significantly
mitigate the problem. Reviewers appreciated the novelty of the contributions but would have liked to see an exhaustive analysis and characterization of all the common causes of duplicates in real world traces. This work is only a first step in fully understanding all the dynamics involved in redundant BGP update messages.

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