| 摘要 |
In an ATM switch, an input port number, an input VPI and an input VCI are used to generate a header appended to the cell when the cell is transmitted. The input port number and the input VPI are combined to form a pointer to a look-up table (LUT). The LUT entry contains a first portion of a pointer to an Input Translation Table (ITT). An ITT entry provides sufficient information to generate the header. The LUT entry contains also some or all of the bits of a mask to be applied to the input VCI to obtain a second portion of the pointer to the ITT. The number of the mask bits is variable. All the mask bits are 1. The mask bits are separated from the first portion of the ITT pointer by a 0 bit.
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