LOAD SHARING FOR MULTIPROCESSOR NETWORK NODES

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1 LOAD SHARING FOR MULTIPROCESSOR NETWORK NODES THÈSE N O 2725 (2003) PRÉSENTÉE À LA FACULTÉ INFORMATIQUE ET COMMUNICATIONS SECTION DES SYSTÈMES DE COMMUNICATION ÉCOLE POLYTECHNIQUE FÉDÉRALE DE LAUSANNE POUR L'OBTENTION DU GRADE DE DOCTEUR ÈS SCIENCES TECHNIQUES PAR Lukas KENCL Master en Informatique, Charles University, Prague, République Tchèque et de nationalité tchèque acceptée sur proposition du jury: Prof. J.-Y. Le Boudec, directeur de thèse Dr P. Droz, rapporteur Dr T. Przygienda, rapporteur Dr J. Rexford, rapporteur Prof. P. Thiran, rapporteur Lausanne, EPFL 2003

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5 Abstract This thesis discusses techniques for sharing the processing load among multiple processing units within systems that act as nodes in a data communications network. Load-sharing techniques have been explored in the field of computer science for many years and their benefits are well known, including better utilization of processing capacity and enhanced system fault tolerance. We discuss deploying such methods in the specifics of the networking environment. We concentrate particularly on the data plane, or the data packet-processing tasks. After reviewing the main results in the fields of load sharing and multiprocessor networking systems architectures, we conduct a preparatory optimization study of a router system to gain better understanding of the optimization issues in a particular multiprocessor system. The main contribution of this thesis, the adaptive load-sharing method, is presented next. We first formulate the optimization problem of mapping packets to processors. The goal is to minimize the likelihood of flow reordering, while respecting certain system constraints, such as the acceptable probability of a packet loss. As we show that the task is an N P-complete problem, we propose a heuristic method that uses an adaptive hash-based mapping to assign packets to processors. We demonstrate its advantages and prove that the method adaptation policy possesses the key minimal disruption property with respect to the mapping. In other words, the adaptation results in a minimum number of flows being moved among processing units. Further on, the method is validated in an extensive set of simulations designed to imitate the networking environment. Finally, two sample applications, an architecture of a multiprotocol router and an implementation of a server load balancer on a network processor demonstrate the applicability of the method. iii

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7 Zusammenfassung Thema der vorliegenden Doktorarbeit sind Techniken zur Lastverteilung zwischen Prozessoren in Systemen, welche die Funktion von Netzwerkknoten in einem Datenkommunikationsnetz haben. Techniken zur Lastverteilung werden in der Informatik schon seit vielen Jahren erforscht, und ihre Vorzüge, wie bessere Ausnutzung der Rechnerkapazität und eine grössere Fehlertoleranz des System, sind bestens bekannt. Die vorliegende Arbeit befasst sich mit der Anwendung dieser Methoden unter den spezifischen Bedingungen von Datennetzen. Hierbei liegt der Schwerpunkt der Betrachtung auf der Datenebene, bzw. auf der Verarbeitung von Datenpakten. Nach einer Übersicht zu den wichtigsten Resultaten aus den Bereichen Lastverteilung und Architekturen von Multiprozessor-Netzwerksystemen wird eine erste Optimierungsstudie eines Router-Systems erarbeitet. Ziel ist hier die Erlangung eines tieferen Verständnisses der Optimierungsproblematik am Beispiel eines ausgewählten Multiprozessorsystems. Anschliessend wird der Hauptbeitrag der vorliegenden Doktorarbeit, die Methode adaptiver Lastverteilung, vorgestellt. Zuerst wird das Optimierungsproblem für die Verteilung von Paketströmen auf Prozessoren formuliert. Ziel hierbei ist die Minimierung der akzeptablen Wahrscheinlichkeit einer ungewünschten Neuzuordnung eines Datenstromes bei Berücksichtigung bestimmter Systemvorgaben, wie z.b. der Wahrscheinlichkeit eines Paketverlustes. Da im folgenden gezeigt wird, dass diese Aufgabe ein N P vollständiges Problem ist, wird eine heuristische Methode vorgeschlagen, welche ein adaptives, hash-basiertes Verfahren für die Verteilung der Pakete auf die Prozessoren verwendet. Die Vorzüge dieser Methode werden aufgezeigt und v

8 es wird bewiesen, dass das Adaptionsverfahren die grundlegende Eigenschaft minimaler, durch Neuzuordnung verursachter Paketstromunterbrechungen (minimal disruption property) besitzt. Damit verursacht der Adaptionsvorgang die Verschiebung einer lediglich minimalen Anzahl von Paketströmen zwischen den Prozessoren. Anschliessend wird die Methode in umfassenden Simulationen validiert. Dabei werden typische Einsatzbedingungen modelliert. Die Anwendbarkeit der Methode wird anhand zweier Beispiele der Architektur eines Multiprotokoll-Routers und der Netzwerkprozessor-Implementierung einer Lastverteilung für eine Serverfarm unter Beweis gestellt. vi

9 128 BIBLIOGRAPHY [49] Jennifer Rexford, John Hall, and Kang G. Shin. A router architecture for realtime communication in multicomputer networks. IEEE Transactions on Computers, 47(10): , October [50] K. W. Ross. Hash routing for collections of shared web caches. IEEE Network, 11(6):37 44, November-December [51] Ch. Semeria. Internet backbone routers and evolving Internet design. Juniper Networks white paper, September [52] J. Sethuraman and M. S. Squillante. Optimal stochastic scheduling in multiclass parallel queues. Performance Evaluation Review Vol. 27 1, MIT, [53] A. Shaikh, J. Rexford, and K. G. Shin. Load-sensitive routing of long-lived IP flows. In Proceedings of SIGCOMM 99, September [54] Anees Shaikh, Renu Tewari, and Mukesh Agrawal. On the effectiveness of DNSbased server selection. In Proceedings of the IEEE INFOCOM 2001, Anchorage, AK [55] B. A. Shirazi, A. R. Hurson, and K. M. Kavi (editors). Scheduling and Load Balancing in Parallel and Distributed Systems. IEEE CS Press, [56] Akamai Web site. [57] Speedera Web site. [58] Cisco Systems. Cisco content networking devices, [59] Cisco Systems. Overview: Load balancing with the multinode load balancing (MNLB) feature set for LocalDirector,

10 BIBLIOGRAPHY 129 [60] Coyote Point Systems. Equalizer, [61] A. Tantawy and M. Zitterbart. Multiprocessing in high performance IP routers. In Proceedings of the 3rd IFIP WG 6.1/6.4 Workshop on Protocols for High Speed Networks, Stockholm, May [62] D. G. Thaler and C. V. Ravishankar. Using name-based mappings to increase hit rates. IEEE/ACM Transactions on Networking, 6(1):1 14, February [63] K. Thompson, G. J. Miller, and R. Wilder. Wide-area Internet traffic patterns and characteristics. IEEE Network, 11(6):10 27, November-December [64] J. Turner and T. Wolf. Design issues for high performance active routers. IEEE JSAC, 19(3): , March [65] M. Waldvogel, G. Varghese, J. Turner, and B. Plattner. Scalable high speed IP route lookups. In Proceedings of ACM Sigcomm 97, pages 25 37, Cannes, France, [66] T. Wang. Integer hash functions: principles and solutions, August Ttwang/tech/inthash.htm. [67] X. Xiao and L. Ni. Parallel routing table computation for scalable IP routers. In Proceedings of the IEEE International Workshop on Communication, Architecture, and Applications for Network-based Parallel Computing, pages , Las Vegas, February Published by Springer as Lecture Notes in Computer Science [68] Y. Zhang, L. Breslau, V. Paxson, and S. Shenker. On the characteristics and origins of Internet flow rates. In Proceedings of ACM Sigcomm 02, Pittsburgh, August [69] H. Zhu, T. Yang, Q. Zheng, D. Watson, O. H. Ibarra, and T. Smith. Adaptive load sharing for clustered digital library servers. In Proceedings of the Seventh

11 130 BIBLIOGRAPHY International Symposium on High Performance Distributed Computing, pages , July 1998.

12 Appendix A List of publications and Curriculum Vitae Journal papers L. Kencl, J. Y. Le Boudec. Adaptive Load Sharing for Network Processors. IEEE/ACM Transactions on Networking, in submission. R. Haas, P. Droz, L. Kencl, A. Kind, B. Metzler, C. Jeffries, R. Pletka, M. Waldvogel. Creating Advanced Functions on Network Processors: Experience and Perspectives. IEEE Network, in submission. Conference papers L. Kencl, J. Y. Le Boudec. Adaptive Load Sharing for Network Processors. In Proceedings of the IEEE Infocom 2002, New York, June E. Bowen, C. Jeffries, L. Kencl, A. Kind, R. Pletka. Bandwidth Allocation for Non-Responsive Flows with Active Queue Management. International Zurich Seminar on Broadband Communications 2002, Zurich, Switzerland, February

13 132 APPENDIX A. LIST OF PUBLICATIONS AND CURRICULUM VITAE L. Kencl, B. Radunovic. General Method for Finding the Most Economical Distributed Router Architecture. In Proceedings of the Communication Networks and Distributed Systems Modelling and Simulation Conference 2002, San Antonio, Texas, January Research reports R. Russo, L. Kencl, B. Metzler, P. Droz. Scalable and Adaptive Load Balancing on IBM PowerNP. IBM Research Report No. RZ-3431, July Patents L. Kencl, E. Bowen, P. Droz, B. Metzler. Load Balancing in Data Networks. European Patent Office Application No: , June P. Droz, L. Kencl. Method and System for Processing Data Packets. European Patent Office Application No: , July 2000.

14 Curriculum Vitae Personal Name: Lukas KENCL Date of birth: January 2, 1970 Place of birth: Prague Nationality: Czech Republic Marital status: married Contact Work Address: IBM Zurich Research Laboratory Säumerstrasse 4 CH-8803 Rüschlikon Switzerland Tel.: (+41) lke@zurich.ibm.com lukas.kencl@ieee.org Private Address: Isengrundstrasse 12 CH-8134 Adliswil Switzerland 133

15 134 APPENDIX A. LIST OF PUBLICATIONS AND CURRICULUM VITAE Employment history present Researcher Network Processor Software Group Department of Communication Systems IBM Zurich Research Laboratory 1998 Network Design Specialist Technical Division Eurotel s.r.o., Prague 1997 Oracle Express Consultant VUMS Software a.s., Prague 1997 Assistant Department of Mathematics Prague Institute of Chemical Technology Education present Ph.D. Candidate Laboratory for computer Communication and Applications (LCA) Swiss Federal Institute of Technology (EPFL) Lausanne, Switzerland Micro MBA Program MBA courses in Finance, Marketing and Strategy successful finish in June Graduate School of Communication Systems EPFL, Lausanne successful finish in July 1998 Project: IP Routing Address Lookup Algorithms Evaluation School of Computer Science Faculty of Mathematics and Physics Charles University, Prague graduated M.S. in Computer Science in June 1995 Thesis: Approximations of a Maximum Cut of a Graph