Towards Zero-Time Wakeup of Line Cards in Power-Aware Routers

Tian Pan, Ting Zhang, Junxiao Shi, Yang Li, Linxiao Jin, Fuliang Li, Jiahai Yang, Beichuan Zhang, Xueren Yang, Mingui Zhang, Huichen Dai, Bin Liu

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


As the network infrastructure has been consuming more and more power, various schemes have been proposed to improve the power efficiency of network devices. Many schemes put links to sleep when idle and wake them up when needed. A presumption in these schemes, though, is that router's line cards can be waken up very quickly. However, through systematic measurement of a major vendor's high-end routers, we find that it takes minutes to get a line card ready under the current design. To address this issue, we propose a new line card design that 1) keeps the host processor in a line card standby, which only consumes a small fraction of power but will save considerable wakeup time, and 2) downloads a slim slot of popular prefixes with higher priority, so that the line card will be ready for forwarding most of the traffic much earlier. We design algorithms as well as architecture that ensure fast and correct longest prefix match during prioritized routing prefix download. Experiments on an FPGA-based prototype show that the customized hardware can be ready to forward packets in 127.27 ms, which is 0.3% of the time the original design takes. This can better support numerous power-saving schemes based on the sleep/wakeup mechanism.

Original languageEnglish (US)
Article number7091049
Pages (from-to)1448-1461
Number of pages14
JournalIEEE/ACM Transactions on Networking
Issue number3
StatePublished - Jun 2016


  • Line card
  • power efficiency
  • route lookup
  • wakeup time

ASJC Scopus subject areas

  • Software
  • Computer Science Applications
  • Computer Networks and Communications
  • Electrical and Electronic Engineering


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