Matching Output Queueing with a Combined Input Output Queued Switch

-- The Internet is facing two problems simultaneously: there is a need for a faster switching/routing infrastructure, and a need to introduce guaranteed qualities of service (QoS). Each problem can be solved independently: switches and routers can be made faster by using input-queued crossbars, instead of shared memory systems; and QoS can be provided using WFQ-based packet scheduling. However, until now, the two solutions have been mutually exclusive -- all of the work on WFQ-based scheduling algorithms has required that switches/routers use output-queueing, or centralized shared memory. This paper demonstrates that a Combined Input Output Queueing (CIOQ) switch running twice as fast as an input-queued switch can provide precise emulation of a broad class of packet scheduling algorithms, including WFQ and strict priorities. More precisely, we show that for an switch, a "speedup" of is necessary and a speedup of two is sufficient for this exact emulation. Perhaps most interes...

• Type: Conference
• Year: 1999
• Where: INFOCOM
• Authors: Shang-Tse Chuang, Ashish Goel, Nick McKeown, Balaji Prabhakar
• Keywords: Communications, INFOCOM 1999, Packet Scheduling, Scheduling Algorithms, Shared Memory