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PM7348 参数 Datasheet PDF下载

PM7348图片预览
型号: PM7348
PDF下载: 下载PDF文件 查看货源
内容描述: [ATM/SONET/SDH IC, CMOS, PBGA324,]
分类和应用: ATM异步传输模式
文件页数/大小: 318 页 / 1736 K
品牌: PMC [ PMC-SIERRA, INC ]
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S/UNI-IMA-4 Telecom Standard Product Data Sheet  
Released  
10.1.4 ANY-PHY/UTOPIA Loopback  
For diagnostic purposes, the capability to loopback all Any-PHY/UTOPIA traffic back to the  
Any-PHY/UTOPIA bus is provided. Cells are taken from the Transmit group FIFOs and placed  
into the respective Receive Group FIFOs, or to a single FIFO on a space available basis. If the  
receive interface is in Any-PHY or single address UTOPIA L2 mode, all TX ports are looped  
back to the respective Rx port.  
10.2 IMA Sub-layer  
10.2.1 Overview  
The IMA protocol provides inverse multiplexing of a single ATM stream over multiple physical  
links and reassembles the original cell stream at the far-end. The inverse multiplexing is  
performed on a cell basis; hence, the IMA protocol is described as a cell-based protocol. See  
Figure 10 below.  
The protocol is based upon the concept of an IMA frame. An IMA frame is programmable in  
size and is delineated by an IMA Control Protocol (ICP) Cell. It is recommended that the ICP  
cells of each link in the IMA group be offset from each other to reduce the notification time of  
link/group status changes.  
The transmitter is responsible for aligning the IMA frames on all links within a group, and for  
ensuring that cells are transmitted continuously by adding filler cells as necessary. To maintain  
frame alignment in the presence of independently timed line clocks, a cell based stuffing  
algorithm is utilized.  
Since the IMA frames are aligned on transmission, this allows the receive end to recover the  
IMA frames and align them to remove any differential delay between the physical links.  
Figure 10 Inverse Multiplexing  
Physical Link #0  
IMA Group  
IMA Group  
PHY  
PHY  
PHY  
PHY  
Physical Link #1  
PHY  
PHY  
Single ATM Cell Stream  
from ATM Layer  
Original Cell stream  
passed to ATM Layer  
Physical Link #2  
IMA VirtualLInk  
Tx direction cells distributed across links in round robin sequence  
Rx direction cells recombined into single ATM stream  
Proprietary and Confidential to PMC-Sierra, Inc., and for its customers’ internal use.  
Document No.: PMC-2020889, Issue 2  
52