PM7340 S/UNI-IMA-8
PRELIMINARY
INVERSE MULTIPLEXING OVER ATM
DATA SHEET
PMC-2001723
ISSUE 3
INVERSE MULTIPLEXING OVER ATM
Word Bits
Parameter
Description
15:0 write_ptr
Current delay compensation buffer write pointer
for this link. The least significant portion of the
write pointer is the cell number within the IMA
frame, while the most significant portion
represents the IMA Frame Sequence Number.
The actual number of bits per field depends on
the value for M for this link. Bits 9:0 for
MAX_DCB_DEPTH = 1024 always represent the
actual buffer write pointer (or bits 7:0 for
MAX_DCB_DEPTH = 256).
The write pointer is initialized by the RDAT when a
valid ICP cell is received while in the IMA Hunt
state, and is incremented otherwise. The most
significant bits (not determined by the frame
sequence number) will be synchronized to the
group read pointer upper bits. (If the lower portion
of the write pointer is less than the lower portion
of the read pointer, then the write pointer upper
bits will be set to one greater than the read pointer
upper bits).
Each increment of the write pointer represents a
single cell time at the link line rate. All write
pointers within a group can be compared in order
to determine the differential delay.
RDAT Link Sequence Memory
The RDAT Link Sequence memory contains the current link sequence number for
each link. This information used solely by the RDAT for buffer management. Each
record is one word by 10 bits wide, and is addressed by the physical link number.
MEM_ADDR = Physical Link Number
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
229
PMC [ PMC-SIERRA, INC ]
