Design of a crossbar VOQ real-time switch with clock-driven scheduling for a guaranteed delay bound

Kyungtae Kang, Kyung Joon Park, Lui Sha, Qixin Wang

Research output: Contribution to journalArticlepeer-review


Most commercial network switches are designed to achieve good average throughput and delay needed for Internet traffic, whereas hard real-time applications demand a bounded delay. Our real-time switch combines clearance-time-optimal switching with clock-based scheduling on a crossbar switching fabric. We use real-time virtual machine tasks to serve both periodic and aperiodic traffic, which simplifies analysis and provides isolation from other system operations. We can then show that any feasible traffic will be switched in two clock periods. This delay bound is enabled by introducing one-shot traffic, which can be constructed at the cost of a fixed delay of one clock period. We carry out simulation to compare our switch with the popular iSLIP crossbar switch scheduler. Our switch has a larger schedulability region, a bounded lower end-to-end switching delay, and a shorter clearance time which is the time required to serve every packet in the system.

Original languageEnglish (US)
Pages (from-to)117-135
Number of pages19
JournalReal-Time Systems
Issue number1
StatePublished - Jan 2013


  • Bounded delay
  • Clock-driven scheduling
  • Real-time switch
  • Schedulability analysis

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Modeling and Simulation
  • Computer Science Applications
  • Computer Networks and Communications
  • Control and Optimization
  • Electrical and Electronic Engineering


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