Patent ID: 6535479
Filing Date: 2003-03-18
Classification: H04L

Abstract:
A hitless switching system in an asynchronous transfer mode (ATM) apparatus, comprising:a first system switch section having a first cell buffer and set as a current acting system switch section, wherein said first system switch section sequentially stores a sequence of cells in said first cell buffer to sequentially output the stored cells from said first cell buffer while performing a discard priority control to said sequence of cells, and stops the discard priority control when a switching control cell is detected in said sequence of cells; and a second system switch section having a second cell buffer and set as a hot standby system switch section, wherein said second system switch section sequentially stores said input sequence of cells in said second cell buffer to sequentially output the stored cells from said second cell buffer while performing the discard priority control to said sequence of cells, and when said switching control cell is detected in said input cells, and stops the discard priority control and discards the stored cells from said second cell buffer together with the switching control cell, wherein said first system switch section sequentially outputs stored cells from said first cell buffer, sets a first mode of said first system switch section when said switching control cell is detected as one of said sequence of cells, stores said sequence of cells in said first cell buffer in said first mode while stopping said discard priority control to said sequence of cells, and selectively stores said sequence of cells in said first cell buffer in a state in which said first mode is not set while performing said discard priority to said sequence of cells, and wherein said second system switch section does not output stored cells from said second cell buffer in a second mode and sequentially outputs the stored cells from said second cell buffer when said second mode is not set, sets said second mode when said switching control cell is detected in said sequence of cells to said second cell buffer, discards the stored cells from said second cell buffer together with said switching control cell when said second mode is set, stores said sequence of cells in said second cell buffer in said second mode while stopping said discard priority control to said sequence of cells, and selectively stores said sequence of cells in said second cell buffer in a state in which said second mode is not set while performing said discard priority control to said sequence of cells.