PM8621 datasheet(44/184 Pages) PMC

44 / 184 page

NSE-8G™ Standard Product Data Sheet

Preliminary

Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use

Document ID: PMC-2010850, Issue 1

9.3

Transmit 8B/10B Encoder (T8TE)

The Transmit 8B/10B Encoder blocks, T8TE, construct an 8B/10B character stream from an

incoming translated SBI336 or TelecomBus carrying an STS-12/STM-4 equivalent channelized

stream. The T8TE block corrects the running disparity of an 8B/10B character stream and buffers

data in a FIFO before transmission to the transmit serializer block. A total of 32 T8TE blocks are

instantiated in the NSE-20G device.

In SBI mode, these blocks encode the SBI336S stream as shown in Table 2. When configured for

Synchronous mode for DS0 switching, the 8B/10B encoder transmits CAS signaling multiframe

alignment across the SBI336S interface by generating a C1FP character every 48 frame times.

When not configured for DS0 switching, the C1FP character is sent every four frames.

9.3.1

SBI336S 8B/10B Character Encoding

Table 2 shows the mapping of SBI336S bus control bytes and signals into 8B/10B control

characters. The linkrate octet in location V4, V1 and V2, the in-band programming channel, the

V3 octet when it contains data are all carried as data. Justification requests for master timing are

carried in the V5 character so there are three V5 characters used, nominal, negative timing

adjustment request, positive timing adjustment request.

Table 2 SBI336S Character Encoding

Code Group

Name

Curr. RD-

abcdei fghj

Curr. RD+

abcdei fghj

Encoded Signals

Description

Common to All Link Types

K28.5

001111 1010

110000 0101

IC1FP=’b1

C1FP frame and multiframe alignment

K23.7-

111010 1000

Overhead Bytes (columns 1-60 or 1-72

except for C1 and in-band programming

channel), V3 or H3 byte except during

negative justification, byte after V3 or H3

byte during positive justification, unused

bytes in fraction rate links

Asynchronous T1/E1 Links

K27.7-

110110 1000

V5 byte, no justification request

K28.7-

001111 1000

V5 byte, negative justification request

K29.7-

101110 1000

V5 byte, positive justification request

Synchronous T1/E1 Links

K27.7-

110110 1000

V5 byte

Asynchronous DS3/E3 Links

K27.7-

110110 1000

V5 byte, no justification request

K28.7-

001111 1000

V5 byte, negative justification request*

K29.7-

101110 1000

V5 byte, positive justification request*

Fractional Rate Links

K28.7-

001111 1000

V5 byte, send one extra byte request**

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