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PM7340 参数 Datasheet PDF下载

PM7340图片预览
型号: PM7340
PDF下载: 下载PDF文件 查看货源
内容描述: S / UNI ATM反向多路复用, 8个环节 [S/UNI INVERSE MULTIPLEXING FOR ATM, 8 LINKS]
分类和应用: ATM集成电路SONET集成电路SDH集成电路电信集成电路电信电路异步传输模式
文件页数/大小: 334 页 / 2670 K
品牌: PMC [ PMC-SIERRA, INC ]
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PM7340 S/UNI-IMA-8  
PRELIMINARY  
INVERSE MULTIPLEXING OVER ATM  
DATA SHEET  
PMC-2001723  
ISSUE 3  
INVERSE MULTIPLEXING OVER ATM  
state. If an incorrect HCS is not found in this PRESYNC period, then a transition  
to the SYNC state is made, cell delineation is declared, and all non-idle cells with  
a correct HCS are passed on. In the SYNC state, synchronization is not  
relinquished until ALPHA consecutive incorrect HCS patterns are found. If this  
happens, a transition is made back to the HUNT state. The state diagram of the  
cell delineation process is shown in Figure 23.  
Figure 23  
- Cell delineation State Diagram  
correct HCS  
(bit by bit)  
HUNT  
Incorrect HCS  
(cell by cell)  
PRESYNC  
ALPHA  
consecutive  
incorrect HCS's  
(cell by cell)  
DELTA  
SYNC  
consecutive  
correct HCS's  
(cell by cell)  
The values of ALPHA and DELTA determine the robustness of the cell delineation  
method. ALPHA determines the robustness against false misalignments due to  
bit errors. DELTA determines the robustness against false delineation in the  
synchronization process. ALPHA is chosen to be 7 and DELTA is chosen to be 6.  
The loss of cell delineation (LCD) alarm is declared after a programmable  
threshold of incorrect cells occurs while in the HUNT state. The threshold is set  
by the LCD Count Threshold register. The threshold has a default value of 104,  
which translates to 28 ms at 1.55 Mbps. All idle cells may be filtered out and not  
passed to the IMA sub-layer. They are identified as cells containing all-zero VPI  
and VCI fields and a one in the CLP bit. Optionally, unassigned cells (like idle  
cells except CLP is a zero) may also be filtered. Note that these should not be  
filtered for IMA links.  
All cells with an incorrect HCS octet may optionally be droppped. These cells can  
also be preserved and tagged as errored. Preservation of HEC errored cells is  
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE  
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