S/UNI-IMA-4 Telecom Standard Product Data Sheet
Released
Figure 13 Stuff Event with Errored ICP (Advanced Indication)
Time
M-1 Filler or
ATM Layer Cells
Stuff event
ICP Cell
ICP Cell
IFSN # i+3
LSI = 000
ICP Cell
IFSN # i+4
LSI = 111
ICP Cell
IFSN # i+2
LSI = 001
ICP Cell
Errored
ICP Cell
IFSN # i
IFSN # i+3
LSI = 000
LSI = 011
stuff_cnt =7
stuff_cnt =0
stuff_cnt =1
stuff_cnt =2
stuff_cnt =3
IFSN: IMA Frame Sequence Number
LSI: Link Stuffing Indication
Figure 14 Invalid Stuff Sequence (Advanced Indication)
Time
M-1 Filler or
ATM Layer Cells
Stuff event
ICP Cell
IFSN # i+3
LSI = 000
ICP Cell
IFSN # i+3
LSI = 000
ICP Cell
IFSN # i+4
LSI = 111
ICP Cell
IFSN # i+2
LSI = 001
ICP Cell
IFSN #i+1
LSI=001
ICP Cell
IFSN # i
LSI = 011
stuff_cnt =7
stuff_cnt =0
stuff_cnt =1
stuff_cnt =2
stuff_cnt =3
IFSN: IMA Frame Sequence Number
LSI: Link Stuffing Indication
IMA Frame Synchronization with Stuff Events
The RDAT will maintain synchronization while receiving stuff events subjected to HEC or CRC
errors, as shown in Figure 15. When one of the ICP cells comprising a stuff event is errored or
invalid, the other will be used. If both are errored or invalid, then the internally maintained stuff
count will be used to identify the stuff event (given that the advanced indicators were correct).
All of the cases assume that the IFSM is in the IMA Sync state prior to the window shown, and
that the current errored/invalid counts are zero. Cases (1) through (6) require that alpha or beta
be programmed to a value greater than one for synchronization to be maintained. Case (7)
requires that alpha or beta be programmed to a value greater than two for synchronization to be
maintained. Case (7) also requires that advance link stuff indication be given prior to the
window shown in order to detect the stuff event.
Proprietary and Confidential to PMC-Sierra, Inc., and for its customers’ internal use.
Document No.: PMC-2020889, Issue 2
60
PMC [ PMC-SIERRA, INC ]
