Revisiting route caching: The world should be flat

Changhoon Kim, Matthew Caesar, Alexandre Gerber, Jennifer L. Rexford

Research output: Chapter in Book/Report/Conference proceedingConference contribution

51 Scopus citations


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.

Original languageEnglish (US)
Title of host publicationPassive and Active Network Measurement - 10th International Conference, PAM 2009, Proceedings
Number of pages10
StatePublished - 2009
Event10th International Conference on Passive and Active Network Measurement, PAM 2009 - Seoul, Korea, Republic of
Duration: Apr 1 2009Apr 3 2009

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349


Other10th International Conference on Passive and Active Network Measurement, PAM 2009
Country/TerritoryKorea, Republic of

All Science Journal Classification (ASJC) codes

  • Theoretical Computer Science
  • General Computer Science


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