PM7341 datasheet(35/413 Pages) PMC

35 / 413 page

PRELIMINARY

INVERSE MULTIPLEXING OVER ATM

PM7341 S/UNI-IMA-84

DATASHEET

PMC-2000223

ISSUE 4

INVERSE MULTIPLEXING OVER ATM

PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE

delineation features of the S/UNI IMA-84 for implementing either ATM over E1 or

ATM over T1.

In the transmit direction, the S/UNI-IMA-84 accepts cells from the Any-

PHY/UTOPIA Interface. The S/UNI-IMA-84 performs the IMA function which

consists of taking a cell stream destined for a group and distributing the cells in a

round-robin fashion to the links within a group, adding IMA Control Protocol (ICP)

cells, filler cells, and stuff cells as needed. The ICP cells convey state information

to the far end and are used to format an IMA frame. The IMA Frame is used as a

mechanism to synchronize the links at the far end. Cell rate decoupling is

performed at the IMA sub-layer via filler cells. Filler cells are used instead of

physical layer cells for cell rate decoupling, thus a continuous stream of cells is

sent to the TC layer. The stuff cells are used to maintain synchronization between

the links in a group by absorbing the rate differential when links are running on

different clocks.

The data from the IMA sub-layer is passed on to the TC layer. In the TC layer, the

HEC is calculated and inserted into the cell headers and optional scrambling of

the payload is performed. The cell stream is then mapped into the T1 or E1

payload with zeros inserted for the framing and overhead bits or bytes. The links

are then transmitted via either the high density SBI interface or the clock and

data interface. The S/UNI-IMA-84 acts as a clock slave – i.e., the clock is

provided from logic external to the S/UNI-IMA-84. An optional common-clock

mode is provided to enable all links to run from the same clock.

If using an unchannelized clock and data interface, the data is not mapped into

the T1/E1 payload but is transmitted one bit for each provided clock pulse.

On the receive side, the framed data is received from either the SBI or the

clock/data interface, and the ATM cell data is extracted from the T1, E1 or DS3

frame structure.

If using an unchannelized clock and data interface, the data is received one bit

for each provided clock pulse.

The TC layer searches for cell delineation as per the procedures outlined in ITU-

T Recommendation I.432.1. Once cell delineation is obtained, the payload is

optionally descrambled and the cells are passed to the IMA sub-layer. The TC

layer provides counts of errored headers as well as OCD and LCD error

interrupts.

The receive IMA sublayer performs IMA-frame delineation and stuff-cell removal.

Based upon the ICP cell information, the S/UNI-IMA-84 determines the

PM7341 Datasheet(PDF) 35 Page - PMC-Sierra, Inc

PM7341 Datasheet(HTML) 35 Page - PMC-Sierra, Inc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL