Browse Prior Art Database

Arbitration Control Method for Multiple Multiplex Telephone Switching Buffers

IP.com Disclosure Number: IPCOM000120327D
Original Publication Date: 1991-Apr-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 3 page(s) / 107K

Publishing Venue

IBM

Related People

Andrade, RJ: AUTHOR [+6]

Abstract

Described is an arbitration control method and hardware embodiment for multiple multiplex buffers, also known as "Ping-Pong" buffers, as used in telephone switching mechanisms. The arbitration controls are used with master control units interfaced to slave units and are designed to reduce the size of the switching buffers by dynamically controlling channel switching time.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Arbitration Control Method for Multiple Multiplex Telephone Switching
Buffers

      Described is an arbitration control method and hardware
embodiment for multiple multiplex buffers, also known as "Ping-Pong"
buffers, as used in telephone switching mechanisms.  The arbitration
controls are used with master control units interfaced to slave units
and are designed to reduce the size of the switching buffers by
dynamically controlling channel switching time.

      Typically, interfacing a time division multiplex (TDM) bus to a
telephone line for traffic (voice or data) channels is performed at
high speed with multiple buffers (Ping-Pongs).  The multiple buffers
exchange data between two interfaces which normally run at an
asynchronous rate utilizing control logic to synchronize the
switching of the Ping-Pong buffers.  The switching is normally
performed in response to a request from the master interface.
However, in some cases the switching is performed when the slave
interface is not ready, thereby causing slips to occur.  To avoid
this problem, in prior art a large buffer was used so that more time
is available to perform the switching without losing data.

      The concept described herein provides an arbitration control
whereby Ping-Pong switching logic dynamically determines the required
switching time.  The method provides more time for the slave to
switch, thereby decreasing the probability of a slip.  It is
considered more reliable than a fixed buffer size since a slip is
asynchronously detected at the time that it occurs and is not based
on a synchronous counter value.

      The arbitration is performed between two opposite port
interfaces, the TDM bus and the T-interface or the U-interface to
handle Ping-Pong switching.  In addition, the controls can be
implemented with other types of port interfaces, such as X.25 and
high-level data link controllers (HDLC), etc.  The master port
interface is the TDM bus containing the following characteristics:
     TDM bus traffic commands for reads and writes from the
     Ping-Pong buffer.
     A Time Slot-O signal indicating the beginning of a
     frame.

      The key characteristic of the time interface is a signal
indicating that the last line...