Anycast-aware transport for content delivery networks

ABSTRACT

Anycast-based content delivery networks (CDNs) have many properties that make them ideal for the large scale distribution of content on the Internet. However, because routing changes can result in a change of the endpoint that terminates the TCP session, TCP session disruption remains a concern for anycast CDNs, especially for large file downloads. In this paper we demonstrate that this problem does not require any complex solutions. In particular, we present the design of a simple, yet efficient, mechanism to handle session disruptions due to endpoint changes. With our mechanism, a client can continue the download of the content from the point at which it was before the endpoint change. Furthermore, CDN servers purge the TCP connection state quickly to handle frequent switching with low system overhead.

We demonstrate experimentally the effectiveness of our proposed mechanism and show that more complex mechanisms are not required. Specifically, we find that our mechanism maintains high download throughput even with a reasonably high rate of endpoint switching, which is attractive for load balancing scenarios. Moreover, our results show that edge servers can purge TCP connection state after a single timeout-triggered retransmission without any tangible impact on ongoing connections. Besides improving server performance, this behavior improves the resiliency of the CDN to certain denial of service attacks.

REFERENCES

• 1: Akamai Inc. http://www.akamai.com/html/perspectives/index.html.
• 2: IP Dummynet. http://info.iet.unipi.it/~luigi/ip_dummynet/.
• 3: Keynote Data Accuracy and Statistical Analysis for Performance Trending and Service Level Management. http://www.keynote.com/docs/whitepapers/keynote_data_accuracy_for_WebPerformance.pdf.
• 4: TCP Manual. http://linux.die.net/man/7/tcp.
• 5: The Apache Web Server. http://httpd.apache.org/.
• 6: Hussein A. Alzoubi , Seungjoon Lee , Michael Rabinovich , Oliver Spatscheck , Jacobus Van der Merwe, Anycast CDNS revisited, Proceeding of the 17th international conference on World Wide Web, April 21-25, 2008, Beijing, China [doi>10.1145/1367497.1367536]
• 7: Hitesh Ballani , Paul Francis , Sylvia Ratnasamy, A measurement-based deployment proposal for IP anycast, Proceedings of the 6th ACM SIGCOMM conference on Internet measurement, October 25-27, 2006, Rio de Janeriro, Brazil [doi>10.1145/1177080.1177109]
• 8: T. Hardie, Distributing Authoritative Name Servers via Shared Unicast Addresses, RFC Editor, 2002
• 9: G. Huston. Faster. The ISP Column, June 2005.
• 10: Hyewon Jun , Matt Sanders , Mostafa H. Ammar , Ellen W. Zegura, Binding Clients to Replicated Servers: Initial and Continuous Binding, Proceedings of the The Ninth IEEE Workshop on Future Trends of Distributed Computing Systems, p.168, May 28-30, 2003
• 11: C. R. Kalmanek. Evolving nature of content delivery. http://www.dcia.info/activities/p2pmsla2007/ATT.pdf.
• 12: Roger P. Karrer , Edward W. Knightly, TCP-PARIS: a Parallel Download Protocol for Replicas, Proceedings of the 10th International Workshop on Web Content Caching and Distribution, p.15-25, September 12-13, 2005 [doi>10.1109/WCW.2005.20]
• 13: Keynote. http://www.keynote.com/.
• 14: Kyu-Han Kim , Yujie Zhu , Raghupathy Sivakumar , Hung-Yun Hsieh, A receiver-centric transport protocol for mobile hosts with heterogeneous wireless interfaces, Wireless Networks, v.11 n.4, p.363-382, July 2005 [doi>10.1007/s11276-005-1763-2]
• 15: Linux TC. http://lartc.org/.
• 16: Zhuoqing Morley Mao , Charles D. Cranor , Fred Douglis , Michael Rabinovich , Oliver Spatscheck , Jia Wang, A Precise and Efficient Evaluation of the Proximity Between Web Clients and Their Local DNS Servers, Proceedings of the General Track of the annual conference on USENIX Annual Technical Conference, p.229-242, June 10-15, 2002
• 17: Jeffrey Pang , Aditya Akella , Anees Shaikh , Balachander Krishnamurthy , Srinivasan Seshan, On the responsiveness of DNS-based network control, Proceedings of the 4th ACM SIGCOMM conference on Internet measurement, October 25-27, 2004, Taormina, Sicily, Italy [doi>10.1145/1028788.1028792]
• 18: Pablo Rodriguez , Ernst W. Biersack, Dynamic parallel access to replicated content in the internet, IEEE/ACM Transactions on Networking (TON), v.10 n.4, p.455-465, August 2002 [doi>10.1109/TNET.2002.801413]
• 19: Alan Shieh , Andrew C. Myers , Emin Gün Sirer, Trickles: a stateless network stack for improved scalability, resilience, and flexibility, Proceedings of the 2nd conference on Symposium on Networked Systems Design & Implementation, p.175-188, May 02-04, 2005
• 20: Alex C. Snoeren , David G. Andersen , Hari Balakrishnan, Fine-grained failover using connection migration, Proceedings of the 3rd conference on USENIX Symposium on Internet Technologies and Systems, p.19-19, March 26-28, 2001, San Francisco, California
• 21: Ao-Jan Su , Aleksandar Kuzmanovic, Thinning akamai, Proceedings of the 8th ACM SIGCOMM conference on Internet measurement, October 20-22, 2008, Vouliagmeni, Greece [doi>10.1145/1452520.1452525]
• 22: Michal Szymaniak , Guillaume Pierre , Mariana Simons-Nikolova , Maarten van Steen, Enabling service adaptability with versatile anycast: Research Articles, Concurrency and Computation: Practice & Experience, v.19 n.13, p.1837-1863, September 2007 [doi>10.1002/cpe.v19:13]
• 23: Patrick Verkaik , Dan Pei , Tom Scholl , Aman Shaikh , Alex C. Snoeren , Jacobus E. van der Merwe, Wresting control from BGP: scalable fine-grained route control, 2007 USENIX Annual Technical Conference on Proceedings of the USENIX Annual Technical Conference, p.1-14, June 17-22, 2007, Santa Clara, CA

INDEX TERMS

Primary Classification:
  C. Computer Systems Organization
  C.2 COMPUTER-COMMUNICATION NETWORKS
      C.2.5 Local and Wide-Area Networks
          Subjects: Internet (e.g., TCP/IP)

Additional Classification:
  C. Computer Systems Organization
  C.2 COMPUTER-COMMUNICATION NETWORKS
      C.2.1 Network Architecture and Design
          Subjects: Network communications

General Terms:
Design, Performance

Keywords:
anycast, connection disruption, content delivery networks