research-article
Authors: Maria Apostolaki, Ankit Singla, and Laurent Vanbever
SOSR '21: Proceedings of the ACM SIGCOMM Symposium on SDN Research (SOSR)
October 2021
Pages 41 - 53
Published: 08 November 2021 Publication History
- 7citation
- 240
- Downloads
Metrics
Total Citations7Total Downloads240Last 12 Months80
Last 6 weeks9
New Citation Alert added!
This alert has been successfully added and will be sent to:
You will be notified whenever a record that you have chosen has been cited.
To manage your alert preferences, click on the button below.
Manage my Alerts
New Citation Alert!
Please log in to your account
Get Access
- Get Access
- References
- Media
- Tables
- Share
Abstract
Internet routing can often be sub-optimal, with the chosen routes providing worse performance than other available policy-compliant routes. This stems from the lack of visibility into route performance at the network layer. While this is an old problem, we argue that recent advances in programmable hardware finally open up the possibility of performance-aware routing in a deployable, BGP-compatible manner.
We introduce RouteScout, a hybrid hardware/software system supporting performance-based routing at ISP scale. In the data plane, RouteScoutleverages P4-enabled hardware to monitor performance across policy-compliant route choices for each destination, at line-rate and with a small memory footprint. RouteScout'scontrol plane then asynchronously pulls aggregated performance metrics to synthesize a performance-aware forwarding policy.
We show that RouteScoutcan monitor performance across most of an ISP's traffic, using only 4 MB of memory. Further, its control can flexibly satisfy a variety of operator objectives, with sub-second operating times.
References
[1]
[n.d.]. Caida Anonymized Internet Traces 2015. http://www.caida.org/data/passive/passive_2015_dataset.xml.
[2]
[n.d.]. CAIDA Macroscopic Internet Topology Data Kit. https://www.caida.org/data/internet-topology-data-kit/.
[3]
[n.d.]. Gurobi Solver. http://www.gurobi.com/.
[4]
[n.d.]. RIPE NCC. RIPE Atlas. https://atlas.ripe.net.
[5]
2018. Barefoot. Barefoot Tofino, World's fastest P4-programmable Ether- net switch ASICs. https://barefootnetworks.com/products/brief-tofino/.
[6]
2018. The top 500 sites on the web. https://www.alexa.com/topsites.
[7]
2019. P4 behavioral model. https://github.com/p4lang/behavioral-model.
[8]
Aditya Akella, Bruce Maggs, Srinivasan Seshan, and Anees Shaikh. 2008. On the performance benefits of multihoming route control. IEEE/ACM Transactions on Networking (TON)16, 1 (2008), 91--104.
Digital Library
[9]
Aditya Akella, Bruce Maggs, Srinivasan Seshan, Anees Shaikh, and Ramesh Sitaraman. 2003. A measurement-based analysis of multihoming. In Proceedings of the 2003 conference on Applications, technologies, architectures, and protocols for computer communications.ACM, 353--364.
Digital Library
[10]
Aditya Akella, Srinivasan Seshan, and Anees Shaikh. 2004. Multihoming Performance Benefits: An Experimental Evaluation of Practical Enterprise Strategies. In USENIX Annual Technical Conference, General Track.113-126.
[11]
David Andersen, Hari Balakrishnan, Frans Kaashoek, and Robert Morris. 2002. Resilient overlay networks. ACM SIGCOMM Computer Communication Review32, 1 (2002), 66--66.
[12]
Todd Arnold, Matt Calder, Italo Cunha, Arpit Gupta, Harsha V. Madhyastha, Michael Schapira, and Ethan Katz-Bassett. 2019. Beating BGP is Harder than We Thought. In ACM HotNets.
[13]
Ran Ben-Basat, Xiaoqi Chen, Gil Einziger, and Ori Rottenstreich. 2018. Efficient Measurement on Programmable Switches Using Probabilistic Recirculation. 2018 IEEE 26th International Conference on Network Protocols (ICNP)(Sep 2018). https://doi.org/10.1109/icnp.2018.00047
[14]
Debopam Bhattacherjee, Waqar Aqeel, Ilker Nadi Bozkurt, Anthony Aguirre, Balakrishnan Chandrasekaran, P Godfrey, Gregory Laughlin, Bruce Maggs, and Ankit Singla. 2018. Gearing up for the 21st century space race. In ACM HotNets.
[15]
Ethan Blanton and Mark Allman. 2002. On making TCP more robust to packet reordering. ACM SIGCOMM Computer Communication Review32, 1 (2002), 20--30.
[16]
Burton H. Bloom. 1970. Space/Time Trade-offs in Hash Coding with Allowable Errors. Commun. ACM13, 7 (July 1970), 422--426. https://doi.org/10.1145/362686.362692
[17]
Alessio Botta, Alberto Dainotti, and Antonio Pescapè. 2012. A tool for the generation of realistic network workload for emerging networking scenarios. Computer Networks56, 15 (2012), 3531--3547.
[18]
Alan Boyle. 2019. Amazon to offer broadband access from orbit with 3,236-satellite 'Project Kuiper' constellation. https://www.geekwire.com/2019/amazon-project-kuiper-broadband-satellite/.
[19]
Fangfei Chen, Ramesh K Sitaraman, and Marcelo Torres. 2015. End-user mapping: Next generation request routing for content delivery. ACM SIGCOMM Computer Communication Review45, 4 (2015), 167--181.
Digital Library
[20]
Xiaoqi Chen, Hyojoon Kim, Javed M Aman, Willie Chang, Mack Lee, and Jennifer Rexford. 2020. Measuring tcp round-trip time in the data plane. In Proceedings of the Workshop on Secure Programmable Network Infrastructure.35-41.
Digital Library
[21]
Kenjiro Cho, Koushirou Mitsuya, and Akira Kato. 2000. Traffic Data Repository at the WIDE Project. In Proceedings of the Annual Conference on USENIX Annual Technical Conference(San Diego, California) (ATEC '00).USENIX Association, Berkeley, CA, USA, 51--51. http://dl.acm.org/citation.cfm?id=1267724.1267775
Digital Library
[22]
Cisco Performance Routing (PfR). [n.d.]. https://www.cisco.com/c/en/us/products/ios-nx-os-software/performance-routing-pfr/index.html.
[23]
Benoit Claise. 2004. Cisco Systems NetFlow Services Export Version 9. RFC 3954 (Informational). http://www.ietf.org/rfc/rfc3954.txt.
[24]
D. Clark, S. Bauer, K. Claffy, A. Dhamdhere, B. Huffaker, W. Lehr, and M. Luckie. 2014. Measurement and Analysis of Internet Interconnection and Congestion. In Telecommunications Policy Research Conference (TPRC).
[25]
Anwar Elwalid, Cheng Jin, Steven Low, and Indra Widjaja. 2001. MATE: MPLS adaptive traffic engineering. (2001).
[26]
Li Fan, Pei Cao, Jussara Almeida, and Andrei Z. Broder. 2000. Summary Cache: A Scalable Wide-area Web Cache Sharing Protocol. IEEE/ACM Trans. Netw.8, 3 (June 2000), 281--293. https://doi.org/10.1109/90.851975
[27]
Wenjia Fang and Larry Peterson. 1999. Inter-AS traffic patterns and their implications. In Seamless Interconnection for Universal Services. Global Telecommunications Conference. GLOBECOM'99.(Cat. No. 99CH37042), Vol. 3. IEEE, 1859--1868.
[28]
Riot Games. 2016. Fixing the Internet for Real-time Applications. https://engineering.riotgames.com/news/fixing-internet-real-time-applications-part-ii.
[29]
Lixin Gao and Jennifer Rexford. 2001. Stable internet routing without global coordination. IEEE/ACM Trans. Netw.9 (December 2001), 681--692. Issue 6. https://doi.org/10.1109/90.974523
[30]
Ruomei Gao, Constantinos Dovrolis, and Ellen W Zegura. 2006. Avoiding Oscillations Due to Intelligent Route Control Systems. In INFOCOM.
[31]
Mojgan Ghasemi, Theophilus Benson, and Jennifer Rexford. 2017. Dapper: Data Plane Performance Diagnosis of TCP. In Proceedings of the Symposium on SDN Research(Santa Clara, CA, USA) (SOSR '17).ACM, New York, NY, USA, 61--74. https://doi.org/10.1145/3050220.3050228
Digital Library
[32]
David K Goldenberg, Lili Qiuy, Haiyong Xie, Yang Richard Yang, and Yin Zhang. 2004. Optimizing cost and performance for multihoming. In ACM SIGCOMM Computer Communication Review, Vol. 34. ACM, 79--92.
[33]
Michael T. Goodrich and Michael Mitzenmacher. 2011. Invertible Bloom Lookup Tables. CoRRabs/1101.2245 (2011). http://arxiv.org/abs/1101.2245
Digital Library
[34]
Thomas Holterbach, Edgar Costa Molero, Maria Apostolaki, Alberto Dainotti, Stefano Vissicchio, and Laurent Vanbever. 2019. Blink: Fast connectivity recovery entirely in the data plane. In 16th { USENIX} Symposium on Networked Systems Design and Implementation ({NSDI} 19).161-176.
[35]
Kuo-Feng Hsu, Ryan Beckett, Ang Chen, Jennifer Rexford, and David Walker. 2020. Contra: A Programmable System for Performance-aware Routing. In 17th USENIX Symposium on Networked Systems Design and Implementation (NSDI 20).USENIX Association, Santa Clara, CA, 701--721. https://www.usenix.org/conference/nsdi20/presentation/hsu
[36]
IP SLAs Configuration Guide. Cisco IOS. [n.d.]. https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipsla/configuration/15-mt/sla-15-mt-book/sla_icmp_echo.html.
[37]
iPerf - The ultimate speed test tool for TCP, UDP and SCTP. [n.d.]. https://iperf.fr/.
[38]
Muhammad Faisal Iqbal, Muhammad Zahid, Durdana Habib, and Lizy Kurian John. 2019. Efficient Prediction of Network Traffic for Real-Time Applications. Journal of Computer Networks and Communications2019 (2019).
[39]
Hao Jiang and Constantinos Dovrolis. 2002. Passive Estimation of TCP Roundtrip Times. SIGCOMM Comput. Commun. Rev.32, 3 (July 2002), 75--88. https://doi.org/10.1145/571697.571725
[40]
Xin Jin, Xiaozhou Li, Haoyu Zhang, Robert Soulé, Jeongkeun Lee, Nate Foster, Changhoon Kim, and Ion Stoica. 2017. NetCache: Balancing Key-Value Stores with Fast In-Network Caching. In Proceedings of the 26th Symposium on Operating Systems Principles(Shanghai, China) (SOSP '17).ACM, New York, NY, USA, 121--136. https://doi.org/10.1145/3132747.3132764
Digital Library
[41]
Srikanth Kandula, Dina Katabi, Bruce Davie, and Anna Charny. 2005. Walking the tightrope: Responsive yet stable traffic engineering. In ACM SIGCOMM Computer Communication Review, Vol. 35. ACM, 253--264.
Digital Library
[42]
Jorma Kilpi. 2008. IP-availability and SLA. In Proc. of the International Euro-NF Workshop on Traffic Management and Traffic Engineering for the Future Internet.
[43]
Changhoon Kim, Anirudh Sivaraman, Naga Praveen Katta, Antonin Bas, Advait Dixit, and Lawrence J Wobker. 2015. In-band Network Telemetry via Programmable Dataplanes.
[44]
Tobias Klenze, Giacomo Giuliari, Christos Pappas, Adrian Perrig, and David Basin. 2018. Networking in Heaven as on Earth. In ACM HotNets.
[45]
Yuliang Li, Rui Miao, Changhoon Kim, and Minlan Yu. 2016. FlowRadar: A Better NetFlow for Data Centers. In NSDI.USENIX Association, Santa Clara, CA, USA. https://www.usenix.org/conference/nsdi16/technical-sessions/presentation/li-yuliang
[46]
Zaoxing Liu, Antonis Manousis, Gregory Vorsanger, Vyas Sekar, and Vladimir Braverman. 2016. One sketch to rule them all: Rethinking network flow monitoring with univmon. In Proceedings of the 2016 ACM SIGCOMM Conference.ACM, 101--114.
Digital Library
[47]
Pascal Mérindol, Virginie Van den Schrieck, Benoit Donnet, Olivier Bonaventure, and Jean-Jacques Pansiot. 2009. Quantifying Ases Multiconnectivity Using Multicast Information. In Proceedings of the 9th ACM SIGCOMM Conference on Internet Measurement(Chicago, Illinois, USA) (IMC '09).Association for Computing Machinery, New York, NY, USA, 370--376. https://doi.org/10.1145/1644893.1644937
Digital Library
[48]
Masoud Moshref, Minlan Yu, Ramesh Govindan, and Amin Vahdat. 2014. DREAM: dynamic resource allocation for software-defined measurement. In ACM SIGCOMM Computer Communication Review, Vol. 44. ACM, 419--430.
Digital Library
[49]
Srinivas Narayana, Anirudh Sivaraman, Vikram Nathan, Prateesh Goyal, Venkat Arun, Mohammad Alizadeh, Vimalkumar Jeyakumar, and Changhoon Kim. 2017. Language-directed hardware design for network performance monitoring. In Proceedings of the Conference of the ACM Special Interest Group on Data Communication.ACM, 85--98.
Digital Library
[50]
Peter Phaal, Sonia Panchen, and Neil McKee. 2001. InMon Corporation's sFlow: A Method for Monitoring Traffic in Switched and Routed Networks. RFC 3176 (Informational). http://www.ietf.org/rfc/rfc3176.txt.
[51]
Y. Rekhter, T. Li, and S. Hares. 2006. A Border Gateway Protocol 4 (BGP-4). RFC 4271 (Draft Standard). http://www.ietf.org/rfc/rfc4271.txt
[52]
Aimin Sang and San qi Li. 2000. A predictability analysis of network traffic. Proceedings IEEE INFOCOM 2000. Conference on Computer Communications. Nineteenth Annual Joint Conference of the IEEE Computer and Communications Societies (Cat. No.00CH37064)1 (2000), 342--351 vol.1.
[53]
Nadi Sarrar, Steve Uhlig, Anja Feldmann, Rob Sherwood, and Xin Huang. 2012. Leveraging Zipf's law for traffic offloading. ACM SIGCOMM Computer Communication Review42, 1 (2012), 16--22.
[54]
Stefan Savage, Thomas Anderson, Amit Aggarwal, David Becker, Neal Cardwell, Andy Collins, Eric Hoffman, John Snell, Amin Vahdat, Geoff Voelker, and John Zahorjan. 1999. Detour: Informed Internet routing and transport. IEEE Micro(1999).
[55]
Brandon Schlinker, Hyojeong Kim, Timothy Cui, Ethan Katz-Bassett, Harsha V. Madhyastha, Italo Cunha, James Quinn, Saif Hasan, Petr Lapukhov, and Hongyi Zeng. 2017. Engineering Egress with Edge Fabric: Steering Oceans of Content to the World. In ACM SIGCOMM.
[56]
Stephanie AC Schuckers. 2002. Spoofing and anti-spoofing measures. Information Security technical report7, 4 (2002), 56--62.
[57]
SpaceX Starlink. [n.d.]. https://www.spacex.com/webcast.
[58]
Neil Spring, Ratul Mahajan, and Thomas Anderson. 2003. The causes of path inflation. In Proceedings of the 2003 conference on Applications, technologies, architectures, and protocols for computer communications.ACM, 113--124.
Digital Library
[59]
Hongsuda Tangmunarunkit, Ramesh Govindan, and Scott Shenker. 2001. Internet path inflation due to policy routing. In ITCom 2001: International Symposium on the Convergence of IT and Communications.International Society for Optics and Photonics, 188--195.
[60]
Olivier Tilmans, Tobias Bühler, Ingmar Poese, Stefano Vissicchio, and Laurent Vanbever. 2018. Stroboscope: Declarative Network Monitoring on a Budget. In 15th USENIX Symposium on Networked Systems Design and Implementation (NSDI 18).USENIX Association, Renton, WA. https://www.usenix.org/conference/nsdi18/presentation/tilmans
[61]
Vytautas Valancius, Bharath Ravi, Nick Feamster, and Alex C Snoeren. 2013. Quantifying the benefits of joint content and network routing. In ACM SIGMETRICS Performance Evaluation Review, Vol. 41. ACM, 243--254.
Digital Library
[62]
Chen Xiaoqi, Feibish Shir, Landau, Rexford Yaron, Koral andJ ennifer, and Rottenstreich Ori. 2018. Catching the Microburst Culprits with Snappy. https://www.cs.princeton.edu/~jrex/papers/snappy18.pdf.
[63]
Tong Yang, Jie Jiang, Peng Liu, Qun Huang, Junzhi Gong, Yang Zhou, Rui Miao, Xiaoming Li, and Steve Uhlig. 2018. Elastic sketch: Adaptive and fast network-wide measurements. In Proceedings of the 2018 Conference of the ACM Special Interest Group on Data Communication.ACM, 561--575.
Digital Library
[64]
Kok-Kiong Yap, Murtaza Motiwala, Jeremy Rahe, Steve Padgett, Matthew Holliman, Gary Baldus, Marcus Hines, Taeeun Kim, Ashok Narayanan, Ankur Jain, Victor Lin, Colin Rice, Brian Rogan, Arjun Singh, Bert Tanaka, Manish Verma, Puneet Sood, Mukarram Tariq, Matt Tierney, Dzevad Trumic, Vytautas Valancius, Calvin Ying, Mahesh Kallahalla, Bikash Koley, and Amin Vahdat. 2017. Taking the Edge off with Espresso: Scale, Reliability and Programmability for Global Internet Peering. In ACM SIGCOMM.
[65]
Minlan Yu, Lavanya Jose, and Rui Miao. 2013. Software Defined Traffic Measurement with OpenSketch. In Presented as part of the 10th { USENIX} Symposium on Networked Systems Design and Implementation ( {NSDI} 13).29-42.
[66]
Li Yuliang, Miao Rui, Kim‡ Changhoon, and Yu Minlan. 2016. LossRadar: Fast Detection of Lost Packets in Data Center Networks. In CoNEXT(Irvine, California, USA). ACM, New York, NY, USA, 15 pages.
[67]
Yibo Zhu, Nanxi Kang, Jiaxin Cao, Albert Greenberg, Guohan Lu, Ratul Mahajan, Dave Maltz, Lihua Yuan, Ming Zhang, Ben Y. Zhao, and Haitao Zheng. 2015. Packet-Level Telemetry in Large Datacenter Networks. In Proceedings of the 2015 ACM Conference on Special Interest Group on Data Communication(London, United Kingdom) (SIGCOMM '15).ACM, New York, NY, USA, 479--491. https://doi.org/10.1145/2785956.2787483
Digital Library
Cited By
View all
- Gong FRaghunathan DGupta AApostolaki M(2023)Towards Integrating Formal Methods into ML-Based Systems for NetworkingProceedings of the 22nd ACM Workshop on Hot Topics in Networks10.1145/3626111.3628188(48-55)Online publication date: 28-Nov-2023
https://dl.acm.org/doi/10.1145/3626111.3628188
- S A HKumar KMajee ABedarakota ATammana PKannan PShah R(2023)In-Network Probabilistic Monitoring Primitives under the Influence of Adversarial Network InputsProceedings of the 7th Asia-Pacific Workshop on Networking10.1145/3600061.3600086(116-122)Online publication date: 29-Jun-2023
https://dl.acm.org/doi/10.1145/3600061.3600086
- Birge-Lee HApostolaki MRexford J(2022)It takes two to tangoProceedings of the 21st ACM Workshop on Hot Topics in Networks10.1145/3563766.3564107(174-180)Online publication date: 14-Nov-2022
https://dl.acm.org/doi/10.1145/3563766.3564107
- Show More Cited By
Index Terms
Performance-Driven Internet Path Selection
Networks
Network algorithms
Control path algorithms
Network performance evaluation
Network properties
Network dynamics
Network protocols
Network layer protocols
Routing protocols
Network services
Programmable networks
Network types
Public Internet
Recommendations
- A measurement study on the impact of routing events on end-to-end internet path performance
Proceedings of the 2006 conference on Applications, technologies, architectures, and protocols for computer communications
Extensive measurement studies have shown that end-to-end Internet path performance degradation is correlated with routing dynamics. However, the root cause of the correlation between routing dynamics and such performance degradation is poorly ...
Read More
- Quantifying path exploration in the internet
Previous measurement studies have shown the existence of path exploration and slow convergence in the global Internet routing system, and a number of protocol enhancements have been proposed to remedy the problem. However, existing measurements were ...
Read More
- A measurement study on the impact of routing events on end-to-end internet path performance
SIGCOMM '06: Proceedings of the 2006 conference on Applications, technologies, architectures, and protocols for computer communications
Extensive measurement studies have shown that end-to-end Internet path performance degradation is correlated with routing dynamics. However, the root cause of the correlation between routing dynamics and such performance degradation is poorly ...
Read More
Comments
Information & Contributors
Information
Published In
SOSR '21: Proceedings of the ACM SIGCOMM Symposium on SDN Research (SOSR)
October 2021
190 pages
ISBN:9781450390842
DOI:10.1145/3482898
Copyright © 2021 ACM.
Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. Copyrights for components of this work owned by others than ACM must be honored. Abstracting with credit is permitted. To copy otherwise, or republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee. Request permissions from [emailprotected]
Sponsors
- SIGCOMM: ACM Special Interest Group on Data Communication
Publisher
Association for Computing Machinery
New York, NY, United States
Publication History
Published: 08 November 2021
Permissions
Request permissions for this article.
Check for updates
Qualifiers
- Research-article
- Research
- Refereed limited
Funding Sources
- Swiss National Science Foundation Grant
Conference
SOSR '21
Sponsor:
- SIGCOMM
Acceptance Rates
Overall Acceptance Rate 7 of 43 submissions, 16%
Contributors
Other Metrics
View Article Metrics
Bibliometrics & Citations
Bibliometrics
Article Metrics
- View Citations
7
Total Citations
240
Total Downloads
- Downloads (Last 12 months)80
- Downloads (Last 6 weeks)9
Other Metrics
View Author Metrics
Citations
Cited By
View all
- Gong FRaghunathan DGupta AApostolaki M(2023)Towards Integrating Formal Methods into ML-Based Systems for NetworkingProceedings of the 22nd ACM Workshop on Hot Topics in Networks10.1145/3626111.3628188(48-55)Online publication date: 28-Nov-2023
https://dl.acm.org/doi/10.1145/3626111.3628188
- S A HKumar KMajee ABedarakota ATammana PKannan PShah R(2023)In-Network Probabilistic Monitoring Primitives under the Influence of Adversarial Network InputsProceedings of the 7th Asia-Pacific Workshop on Networking10.1145/3600061.3600086(116-122)Online publication date: 29-Jun-2023
https://dl.acm.org/doi/10.1145/3600061.3600086
- Birge-Lee HApostolaki MRexford J(2022)It takes two to tangoProceedings of the 21st ACM Workshop on Hot Topics in Networks10.1145/3563766.3564107(174-180)Online publication date: 14-Nov-2022
https://dl.acm.org/doi/10.1145/3563766.3564107
- Shobhana BNarayana SNath B(2022)Load balancers need in-band feedback controlProceedings of the 21st ACM Workshop on Hot Topics in Networks10.1145/3563766.3564094(76-84)Online publication date: 14-Nov-2022
https://dl.acm.org/doi/10.1145/3563766.3564094
- Michel OSengupta SKim HNetravali RRexford JBarakat CPelsser CBenson TChoffnes D(2022)Enabling passive measurement of zoom performance in production networksProceedings of the 22nd ACM Internet Measurement Conference10.1145/3517745.3561414(244-260)Online publication date: 25-Oct-2022
https://dl.acm.org/doi/10.1145/3517745.3561414
- Kanaya KToyota YMishima WShirokura HEsaki H(2022)QoE-Aware Content Oriented Path Optimization Framework with Egress Peer Engineering2022 Tenth International Symposium on Computing and Networking (CANDAR)10.1109/CANDAR57322.2022.00013(36-45)Online publication date: Nov-2022
- Kunze ISander CWehrle KRüth J(2021)Tracking the QUIC spin bit on TofinoProceedings of the 2021 Workshop on Evolution, Performance and Interoperability of QUIC10.1145/3488660.3493804(15-21)Online publication date: 7-Dec-2021
https://dl.acm.org/doi/10.1145/3488660.3493804
View Options
Get Access
Login options
Check if you have access through your login credentials or your institution to get full access on this article.
Sign in
Full Access
Get this Publication
View options
View or Download as a PDF file.
PDFeReader
View online with eReader.
eReaderMedia
Figures
Other
Tables
