PM7346 datasheet(99/419 Pages) PMC

99 / 419 page

PM7346 S/UNI-QJET

DATASHEET

PMC-960835

ISSUE 6

SATURN QUAD USER NETWORK INTERFACE FOR J2, E3, T3

PMC-SIERRA, INC. PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA INC., AND ITS CUSTOMERS’ INTERNAL USE 78

9.18 SPLT SMDS PLCP Layer Transmitter

The SMDS PLCP Layer Transmitter (SPLT ) Block integrates circuitry to support

DS1, DS3, E1, and G.751 E3 based PLCP frame insertion.

The SPLT automatically inserts the framing (A1, A2) and path overhead

identification (POHID) octets and provides registers or automatic generation of

the F1, B1, G1, M2, M1 and C1 octets.

Registers are provided for the path user channel octet (F1) and the path status

octet (G1). The bit interleaved parity octet (B1) and the FEBE subfield are

automatically inserted.

The DQDB management information octets, M1 and M2 are generated. The type

0 and type 1 patterns described in TA-TSY-000772 are automatically inserted.

The type 1 page counter may be reset using a register bit in the SPLT

Configuration register. Note that this feature is not required for the ATM Forum

compliant DS3 UNI. For this application, the M1 and M2 octets must be set to all

zeros.

The PLCP transmit frame C1 cycle/stuff counter octet and the transmit stuffing

pattern can be referenced to the REF8KI input pin. Alternately, a fixed stuffing

pattern may be inserted into the C1 cycle/stuff counter octet. A looped timing

operating mode is provided where the transmit PLCP timing is derived from the

received timing. In this mode, the C1 stuffing is generated based on the received

stuffing pattern as determined by the SPLR block. When DS1 or E1 PLCP

format is enabled, the pattern 00H is inserted.

When DS3 PLCP format is enabled, the C1 octet indicates the phase of the 375

µs nibble stuffing opportunity cycle. During frame one of the three frame cycle,

the pattern FFH is inserted in the C1 octet, indicating a 13 nibble trailer length.

During frame two, the pattern 00H is inserted, indicating a 14 nibble trailer

length. During frame three, the pattern 66H or 99H is inserted, indicating a 13 or

14 nibble trailer length respectively.

When configured for G.751 E3 PLCP frame format, the C1 octet is used to

indicate the number of octets stuffed in the trailer. The following table shows the

C1 octet pattern for each of the possible octet stuff lengths:

Stuff Length

C1(Hex)

PM7346 Datasheet(PDF) 99 Page - PMC-Sierra, Inc