PM7375-SC datasheet(65/430 Pages) PMC

65 / 430 page

PM7375 LASAR-155

DATA SHEET

PMC-931127

ISSUE 6

LOCAL ATM SAR & PHYSICAL LAYER

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

Cell copying is only supported if the LASAR-155's receive Multipurpose Port is

enabled to source cells using input RXPHYBP. If enabled as a cell source, cell

copying to the Multipurpose Port can be based on the VPI/VCI code and/or PTI

codepoints.

9.4.2 AAL Layer Processing

AAL Layer processing includes Common Part Convergence Sublayer AAL Type 5

Protocol Data Unit (CPAAL5_PDU) reassembly and verification. In addition, a

mechanism for smooth reassembly startup and smooth reassembly shutdown is

provided.

The RALP performs CPAAL5_PDU reassembly by associating cells with the same

VPI/VCI code with a CPAAL5_PDU. The normal indication of the end of a

CPAAL5_PDU is provided using a PTI codepoint while the start of a CPAAL5_PDU

is implicit based on the previous CPAAL5_PDU end indication. When a VC is first

provisioned for reception and a cell for the VC arrives, the RALP starts to

reassemble a CPAAL5_PDU. As additional cells of a CPAAL5_PDU are received,

the RALP continues to accumulate cells for a given CPAAL5_PDU until the

CPAAL5_PDU is terminated either normally or abnormally through an exception.

Reassembly is facilitated using the PCI DMA Controller (PCID) block.

Normal termination of a CPAAL5_PDU results from the reception of a cell with the

appropriate PTI codepoint and valid CPAAL5_PDU Length, Control and CRC-32

fields. The CRC-32 polynomial used is:

x32+x26+x23+x22+x16+x12+x11+x10+x8+x7+x5+x4+x2+x+1.

Abnormal termination of a CPAAL5_PDU can result from either CPAAL5_PDU

length exceptions, Control field exceptions or CRC-32 exceptions. Length

exceptions can result from either the receive CPAAL5_PDU LENGTH field not

matching the received number of CPAAL5_SDU octets, the receive CPAAL5_PDU

LENGTH field equal to zero (indicating a forward abort) or the received

CPAAL5_PDU exceeding the maximum CPAAL5_PDU size. If the current

CPAAL5_PDU under reassembly exceeds the maximum CPAAL5_PDU size, the

CPAAL5_PDU is terminated and all additional cells received are dropped until the

last cell of the CPAAL5_PDU is received. The maximum CPAAL5_PDU size can be

user programmed. Control field exceptions result when the received CPAAL5_PDU

CPI field is non zero. A CRC-32 exception results when the calculated CRC-32 over

the received CPAAL5_PDU does not produce the expected residue.

The RALP block also provides smooth reassembly shut down. Through user

control, the RALP can be configured to either stop reassembly on all VCs

immediately or after the active CPAAL5_PDU has been reassembled.

PM7375-SC Datasheet(PDF) 65 Page - PMC-Sierra, Inc

PM7375-SC Datasheet(HTML) 65 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