LazyCtrl: a scalable hybrid network control plane design for cloud data centers

Kai Zheng, Lin Wang, Baohua Yang, Yi Sun, Steve Uhlig

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)


The advent of software defined networking enables flexible, reliable and feature-rich control planes for data center networks. However, the tight coupling of centralized control and complete visibility leads to a wide range of issues among which scalability has risen to prominence due to the excessive workload on the central controller. By analyzing the traffic patterns from a couple of production data centers, we observe that data center traffic is usually highly skewed and thus edge switches can be clustered into a set of communication-intensive groups according to traffic locality. Motivated by this observation, we present LazyCtrl, a novel hybrid control plane design for data center networks where network control is carried out by distributed control mechanisms inside independent groups of switches while complemented with a global controller. LazyCtrl aims at bringing laziness to the global controller by dynamically devolving most of the control tasks to independent switch groups to process frequent intra-group events near the datapath while handling rare inter-group or other specified events by the controller. We implement LazyCtrl and build a prototype based on Open vSwitch and Floodlight. Trace-driven experiments on our prototype show that an effective switch grouping is easy to maintain in multi-tenant clouds and the central controller can be significantly shielded by staying 'lazy', with its workload reduced by up to 82 percent.

Original languageEnglish
Pages (from-to)115-127
Number of pages13
JournalIEEE Transactions on Parallel and Distributed Systems
Issue number1
Publication statusPublished - 1 Jan 2017
Externally publishedYes


  • software defined networks
  • network control
  • data center
  • cloud computing


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