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Browse Prior Art Database

Adaptive Burst Switching Protocol

IP.com Disclosure Number: IPCOM000121721D
Original Publication Date: 1991-Sep-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 7 page(s) / 345K

Publishing Venue

IBM

Related People

Calvignac, J: AUTHOR [+3]

Abstract

This article describes an improved selection algorithm implemented in a switching mechanism attached to communication devices able to exchange data during assigned time slots through the switching mechanism. This algorithm allows a maximum number of pairs of devices to be connected during each time slot. The SELECTION ALGORITHM is an iteration of the ELEMENTARY SELECTION ALGORITHM which has two types: 1. the BASIC SCHEDULING ALGORIGHM (first iteration) 2. the COMPLEMENTARY SCHEDULING ALGORITHM (subsequent iterations) for which two possible algorithms are proposed: a. the DIRECT COMPLEMENTARY SCHEDULING (DCS) b. the OPTIMIZING COMPLEMENTARY SCHEDULING (OCS)

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 25% of the total text.

Adaptive Burst Switching Protocol

      This article describes an improved selection algorithm
implemented in a switching mechanism attached to communication
devices able to exchange data during assigned time slots through the
switching mechanism. This algorithm allows a maximum number of pairs
of devices to be connected during each time slot.
      The SELECTION ALGORITHM is an iteration of the
          ELEMENTARY SELECTION ALGORITHM which has two types:
             1. the BASIC SCHEDULING ALGORIGHM (first iteration)
             2. the COMPLEMENTARY SCHEDULING ALGORITHM (subsequent
iterations) for which two possible algorithms are proposed:
 a. the DIRECT COMPLEMENTARY SCHEDULING (DCS)
 b. the OPTIMIZING COMPLEMENTARY SCHEDULING (OCS)

      A Time Division Multiplex Bus used in a classical way has the
main disadvantage to reserve a given amount of bandwidth during
connections even if there is no exchange between two devices to which
the given bandwidth resource has been allocated. The ABS protocol
optimizes the packet switching by managing the bandwidth with the two
following techniques:
 1.  Slots on the Bus are permanently re-allocated to the devices
having something to exchange.
 2.  The device-to-device exchange is not just performed on request
but is orderly managed in a way to maximize the number of paired
devices exchanging simultaneously at a given time.
Device-to-device exchange principle

      This principle is described in European Patent APP n_
89480047.3 (A, B, C, D, for example). Briefly, each device considers
the others as potential targets, so every device houses one queue
towards each of the others; these queues have exactly the same
structure as the queues used to exchange over an external network.

      These queues will be called outbound queues.

      If there are n devices interconnected, each device has n-1
outbound queues. There are a total of n*(n-1) outbound queues, one
per couple of distinct devices.

      The connections are not full duplex; a transmission can only
take place if the corresponding outbound queue is not empty.

      Each device has two TDM connections; one is used for the
receive flow, and the other one for the transmit flow. The receive
functions and the transmit functions are executed independently,
i.e., at a given moment device A can transmit data to device B and
receive data from device C.

      Adaptive Burst Switching (ABS) Principles: The stream of frames
is chopped in bursts of 'k' bytes. These bursts are synchronously
exchanged in one time slot, also called burst time. Under optimal
conditions, n bursts from n devices are exchanged in parallel (under
control of a switch); for these n bursts, transmission starts and
ends at the same time; each device sends a burst and receives a
burst.  Depending on the state of the outbound queues, a device might
not be selected.

      The overall exchange is optim...