Revisiting Route Caching: The World Should Be Flat

  • Changhoon Kim
  • Matthew Caesar
  • Alexandre Gerber
  • Jennifer Rexford
Part of the Lecture Notes in Computer Science book series (LNCS, volume 5448)

Abstract

Internet routers’ forwarding tables (FIBs), which must be stored in expensive fast memory for high-speed packet forwarding, are growing quickly in size due to increased multihoming, finer-grained traffic engineering, and deployment of IPv6 and VPNs. To address this problem, several Internet architectures have been proposed to reduce FIB size by returning to the earlier approach of route caching: storing only the working set of popular routes in the FIB. This paper revisits route caching. We build upon previous work by studying flat, uni-class (/24) prefix caching, with modern traffic traces from more than 60 routers in a tier-1 ISP. We first characterize routers’ working sets and then evaluate route-caching performance under different cache replacement strategies and cache sizes. Surprisingly, despite the large number of deaggregated /24 subnets, caching uni-class prefixes can effectively curb the increase of FIB sizes. Moreover, uni-class prefixes substantially simplify a cache design by eliminating longest-prefix matching, enabling FIB design with slower memory technologies. Finally, by comparing our results with previous work, we show that the distribution of traffic across prefixes is becoming increasingly skewed, making route caching more appealing.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    Chang, E., Lu, B., Markhovsky, F.: RLDRAMs vs. CAMs/SRAMs: Part 1, http://www.commsdesign.com/design_corner/OEG20030603S0007
  2. 2.
    How to Choose the Best Router Switching Path for Your Network. Cisco Systems (August 2005), http://www.cisco.com/warp/public/105/20.pdf
  3. 3.
    Partridge, C., Carvey, P., et al.: A 50-Gb/s IP router. IEEE/ACM Trans. Networking (1998)Google Scholar
  4. 4.
    Ballani, H., Francis, P., Cao, T., Wang, J.: Making Routers Last Longer with ViAggre. In: Proc. NSDI (April 2009) (to appear)Google Scholar
  5. 5.
    Kim, C., Caesar, M., Rexford, J.: Floodless in SEATTLE: A Scalable Ethernet Architecture for Large Enterprises. In: Proc. SIGCOMM (August 2008)Google Scholar
  6. 6.
    Caesar, M., Condie, T., Kannan, J., Lakshminarayanan, K., Stoica, I.: ROFL: Routing on Flat Labels. In: Proc. ACM SIGCOMM (September 2006)Google Scholar
  7. 7.
    Farinacci, D., Fuller, V., Oran, D., Meyer, D., Brim, S.: Locator/ID Separation Protocol (LISP). Internet-Draft (work in progress) (December 2008)Google Scholar
  8. 8.
    Andersen, D., Balakrishnan, H., Feamster, N., et al.: Accountable Internet Protocol (AIP). In: Proc. ACM SIGCOMM (2008)Google Scholar
  9. 9.
    Chang, D., Govindan, R., Heidemann, J.: An empirical study of router response to large BGP routing table load. In: Proc. Internet Measurement Workshop (2002)Google Scholar
  10. 10.
    Eatherton, W., Varghese, G., Dittia, Z.: Tree bitmap: Hardware/Software IP Lookups with Incremental Updates. In: ACM Computer Communication Review (2004)Google Scholar
  11. 11.
  12. 12.
    Liu, H.: Routing Prefix Caching in Network Processor Design. In: Proc. International Conference on Computer Communications and Networks (October 2001)Google Scholar
  13. 13.
    Feldmeier, D.: Improving Gateway Performance With a Routing-table Cache. In: Proc. IEEE INFOCOM (1988)Google Scholar
  14. 14.
    Rexford, J., Wang, J., Xiao, Z., Zhang, Y.: BGP Routing Stability of Popular Destinations. In: Proc. Internet Measurement Workshop (November 2002)Google Scholar
  15. 15.
    Jain, R.: Characteristics of Destination Address Locality in Computer Networks: A Comparison of Caching Schemes. Computer Networks and ISDN 18, 243–254 (1989/1990)CrossRefGoogle Scholar
  16. 16.
    McRobb, D.: Path and Round Trip Time Measurements (slides 19-21), http://www.caida.org/publications/presentations/nanog9806/index.html
  17. 17.
    Iannone, L., Bonaventure, O.: On the Cost of Caching Locator/ID Mappings. In: Proc. ACM CoNEXT (December 2007)Google Scholar
  18. 18.
    Partridge, C.: Locality and Route Caches (1996), http://www.caida.org/workshops/isma/9602/positions/partridge.html

Copyright information

© Springer-Verlag Berlin Heidelberg 2009

Authors and Affiliations

  • Changhoon Kim
    • 1
  • Matthew Caesar
    • 2
  • Alexandre Gerber
    • 3
  • Jennifer Rexford
    • 1
  1. 1.Princeton UniversityUSA
  2. 2.UIUCUSA
  3. 3.AT&T Labs–ResearchUSA

Personalised recommendations