xrt94l33 Exar Corporation, xrt94l33 Datasheet - Page 216

• Manufacturer Part Number: xrt94l33
• Description: Multi-channel, Multi-function Device Aggregates 3 Ds3/e3/sts-1 Into Oc3/stm-1
• Manufacturer: Exar Corporation

XRT94L33
Rev.1.2.0.
Figure 33: Illustration of the Functional Block Diagram of the XRT94L33 Mapper IC, with the Transmit
STS-3c POH Processor block high-lighted
SOME BACKGROUND INFORMATION ON THE PATH OVERHEAD (POH) BYTES
For STS-3c applications, the size of the SPE is 9 rows by 261 byte columns. Figure 34 presents a simple
illustration of the STS-3c SPE.
Figure 34 Simple Illustration of the STS-3c SPE
In each case, the first byte column within an STS-3c SPE is referred to as the Path Overhead (POH).
Therefore, in all, the POH consists of a total of nine (9) bytes. Each of these POH bytes is briefly described
below.
J1 – The Path Trace Byte
B3 – The Path BIP-8 Byte
C2 – The Payload Label Byte
G1 – The Path Status Byte
F2 – The Path User Channel Byte
H4 – The Multi-Frame Indicator (not used for ATM and PPP applications)
Z3, Z4 and Z5 – Growth Bytes
The remainder of this section describes how the Transmit STS-3c POH Processor block handles these POH
bytes.
The operation of the “Transmit STS-3c POH Processor” block is discussed in some detail below.
XRT94L33 – Channel 0
Interface
Telecom
Interface
Interface
Telecom
Interface
STS-3
PECL
STS-3
Block
Block
PECL
STS-3
STS-3
STS-3
Block
Block
Block
Bus
CDR
STS-3
Block
Bus
CDR
Processor
Transmit
Processor
Processor
Transmit
Processor
STS-3
Receive
Block
TOH
STS-3
Receive
STS-3
Microprocessor
Block
Block
3-CHANNEL DS3/E3/STS-1 TO STS-3/STM-1 MAPPER IC DATA SHEET
TOH
TOH
STS-3
Microprocessor
Block
TOH
Interface
Interface
Block
Block
Processor
Processor
Transmit
Processor
Processor
Transmit
Receive
STS-3c
STS-3c
Receive
Block
Block
STS-3c
STS-3c
POH
POH
Block
Block
Synthesizer
POH
POH
216
Synthesizer
Clock
Block
Clock
Block
Cell Processor
Cell Processor
Cell Processor
Cell Processor
Processor
Processor
Transmit
Processor
Processor
Transmit
Transmit
Receive
Receive
Transmit
Receive
Block
Block
Receive
Block
ATM
Block
PPP
Block
PPP
Block
ATM
Block
ATM
PPP
PPP
Block
ATM
POS-PHY
POS-PHY
UTOPIA/
Transmit
UTOPIA
Interface
Transmit
Interface
Interface
Interface
POS-PHY
POS-PHY
UTOPIA/
Transmit
Transmit
Receive
Receive
UTOPIA
Interface
Interface
Interface
Interface
Receive
Receive
Block
Block
Block
Block
xr
Block
Block
Block
Block