Summary: Scheduling Protocols for Switches with Large Envelopes
Matthew Andrews
andrews@research.bell­labs.com
Lisa Zhang
ylz@research.bell­labs.com
Bell Laboratories
600­700 Mountain Avenue
Murray Hill, NJ 07974
July 30, 2001
Abstract
Traditionally, switches make scheduling decisions on the granularity of a packet. However,
this is becoming increasingly difficult since network bandwidth is growing rapidly whereas packet
sizes remain largely unchanged. Therefore the service time of an individual packet is decreasing
rapidly. In this paper we study switches that make scheduling decisions on the granularity of
an envelope which can be much larger than a packet in size.
For an output­queued switch with envelope size E, each output chooses one input every E
time steps and transmits packets from this chosen input during the next E steps. For an input­
queued switch with envelope size E, one matching from the inputs to the outputs is computed
every E steps and only the input­output pairs that are defined by this matching are allowed
to transmit packets during the next E steps. Traditional switches correspond to envelope size

Source: Andrews, Matthew - Mathematics of Networks and Systems, Mathematical Sciences Research Center, Bell Laboratories

Collections: Mathematics; Computer Technologies and Information Sciences