Browse Prior Art Database

Dynamic Pacing Window Interface Flow Control

IP.com Disclosure Number: IPCOM000121882D
Original Publication Date: 1991-Oct-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 9 page(s) / 380K

Publishing Venue

IBM

Related People

Horton, VG: AUTHOR [+6]

Abstract

The data exchange process in communication systems consists of passing the data between the requester (or user) and the provider of the data transmission service. The data is contained in primitive constructs (Interface Data Units). Dynamic pacing window interface flow control is a mechanism for controlling the rate of interface data units being exchanged between the user and the provider of the data transmission service in order to not overrun the storage resources of the user or the provider or result in the loss of data units. This method of protection of storage resources provides a mechanism which can be utilized by multiple users of a provider to provide fairness and independence from each other while maintaining the highest data transfer rate possible for the given resource conditions.

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Dynamic Pacing Window Interface Flow Control

      The data exchange process in communication systems
consists of passing the data between the requester (or user) and the
provider of the data transmission service.  The data is contained in
primitive constructs (Interface Data Units). Dynamic pacing window
interface flow control is a mechanism for controlling the rate of
interface data units being exchanged between the user and the
provider of the data transmission service in order to not overrun the
storage resources of the user or the provider or result in the loss
of data units.  This method of protection of storage resources
provides a mechanism which can be utilized by multiple users of a
provider to provide fairness and independence from each other while
maintaining the highest data transfer rate possible for the given
resource conditions.  An additional advantage of this method is that
the provider (in the case of data user pacing window) is not required
to have knowledge of the value of the pacing window, but rather only
its own resource condition.  The provider authorizes the incrementing
of the pacing window value, but the user actually keeps track of the
value of the pacing window.  The analogous is true for the provider
pacing window.

      Data is transferred and acknowledged between two peer entities
by means of a protocol.  Outgoing data is first passed from a sending
(user) entity to its provider of the data transmission service using
primitive constructs. Likewise, received data is passed from the
receiver (provider) entity to the user of the data transmission
service using primitive constructs as shown in Fig. 1.

      Data is sent by the user entity in a DATA.request primitive to
the provider entity.  Likewise, data is sent by the provider entity
in a DATA.indication primitive to the user entity.

      Dynamic pacing window interface flow control is a method for
controlling or pacing the flow of data primitives between the two
local entities.  This mechanism utilizes a pacing window which is the
number of data.request primitives the user is permitted to issue,
without a new authorization, in the case of the user pacing window or
the number of data.indication primitives that the provider is
permitted to issue, in the case of the provider pacing window.  This
pacing window value may be changed dynamically in response to varying
resource conditions.

      The operation of this dynamic pacing window interface flow
control mechanism for data.request primitives (user pacing window) is
as follows:
      .    Configuration parameters establish the values for the
pacing window:
      PWmin  Minimum Pacing Window value (>0)
      PWmax  Maximum Pacing Window value
      PWin   Initial Pacing Window value upon startup
      PWci   Pacing Window change increment
       .   Upon startup the data user may send the PWin number of
data.  requests and then must wait...