tdat04622 ETC-unknow, tdat04622 Datasheet - Page 105

• Manufacturer Part Number: tdat04622
• Description: Tdat Sonet/sdh 155/622/2488 Mbits/s Data Interfaces
• Manufacturer: ETC-unknow

Data Sheet
May 2001
Agere Systems Inc.
Functional Description
Data Engine (DE) Block
Transmit Data Engine (continued)
Prescrambler. The prescrambler block optionally scrambles the payload using a self-synchronizing scrambler with
a generator polynomial of 1 + x
header and trailer, is scrambled; however, HDLC flags are not scrambled. The scrambler may be disabled through
the use of a software register. This scrambler removes excessive 0x7D and 0x7E bytes. For ATM cell and SDL
packet traffic, this block is not used. (By randomizing the data, the scrambler prevents malicious use of the channel
due to escaping 7D and 7E sequences.)
CRC-16/-32 Generator. An optional CRC-16/-32 generator on the whole packet frame can be performed. The gen-
erating polynomial for CRC-16 is 1+ x
x
HDLC Inserter. The HDLC framer provides frame check sequence (FCS) generation and insertion using either the
CRC-ITU or CRC-32 generation polynomials. After optional CRC generation, the HDLC framer performs control
escape (0x7D) stuffing, flag character (0x7E) or abort character (0x7D7E) insertion, and dry mode insertion
(0x7D20, where the last two bytes (the 20 bytes of the default value of 0x7D20) are provisionable).
Postscrambler. The postscrambler block optionally scrambles the payload using a self-synchronizing scrambler
with a generator polynomial of 1 + x
PPP packets, the entire frame, including header and trailer, is scrambled. The scrambler may be disabled through
the use of a software register. For ATM cell and SDL packet traffic, this block is not used.*
PPP Header Attach. The PPP attach function inserts the provisionable 4-byte PPP header if payload control
bit 7 = 1 (addresses 0x10E0—0x10E3). The first and second bytes are set to 0xFF03, and the third and fourth
bytes are set to a value defined by a software register in PPP_Tx_CHAN[0—3] (see register descriptions,
page 234).
If payload control bit 7 = 0 (addresses 0x10E0—0x10E3) (compressed PPP header mode), only the two provision-
able bytes defined by the software register PPP_Tx_CHAN[0—3] can be attached. Note that there is only one soft-
ware register-defined protocol value for each channel.
The PPP attach function provides good packet count on a per-channel basis through four 28-bit counters,
PM_GPC_TX_[0—3] [27:0] (addresses 0x1128—112F).
* The ATM and SDL framer inserters have their own dedicated scramblers.
7
+ x
8
+ x
10
+ x
11
+ x
12
+ x
16
(continued)
+ x
43
(continued)
22
for HDLC and PPP packets. For HDLC frames, the entire frame, including
43
+ x
5
for HDLC and PPP packets, in accordance with RFC1619. For HDLC and
23
+ x
+ x
12
26
+ x
+ x
16
. The generating polynomial for CRC-32 is 1+ x + x
32
.
155/622/2488 Mbits/s Data Interface
TDAT042G5 SONET/SDH
2
+ x
4
+ x
5
77
+