PM8611-BIAP PMC [PMC-Sierra, Inc], PM8611-BIAP Datasheet - Page 35

• Manufacturer Part Number: PM8611-BIAP
• Manufacturer: PMC [PMC-Sierra, Inc]

10.1
10.1.1
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Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use
Document ID: PMC-2010883, Issue 2
Functional Description
SBI Bus Data Formats
The 19.44 MHz SBI bus is a multi-point to multi-point bus. Since each SBS SBI interface
handles the full SBI bus capacity, it will be more common for a single SBS to talk to multiple
devices over the SBI bus, but there is nothing in the SBS that would prevent the SBS from
sharing an SBI bus with other SBI devices.
SBI Multiplexing Structure
The SBI structure uses a locked SONET/SDH structure to fix the position of the TU-3 relative to
the STS-3/STM-1. The SBI is also of fixed frequency and alignment as determined by the
reference clock (SREFCLK19) and frame indicator signal (IC1FP). Frequency deviations are
compensated by adjusting the location of the T1/E1/DS3/E3/TVT1.5/TVT2 channels using
floating tributaries as determined by the V5 indicator and payload signals (IV5[x] and IPL[x]).
TVTs also allow for synchronous operation where SONET/SDH tributary pointers are carried
within the SBI structure in place of the V5 indicator and payload signals (IV5[x] and IPL[x]).
Fractional links use as many bytes as required within a given synchronous payload envelope
(SPE) using the payload signals to indicate bytes carrying valid data.
Table 1 shows the bus structure for carrying T1, E1, TVT1.5, TVT2, DS3, E3 and Fractional
tributaries in a SDH STM-1 like format. Up to 84 T1s, 63 E1s, 84 TVT1.5s, 63 TVT2s, 3 DS3s,
3 E3s or 3 Fractional rate links are carried within the octets labeled SPE1, SPE2 and SPE3 in
columns 16-270. All other octets are unused and are of fixed position. The frame signal (IC1FP)
occurs during the octet labeled C1 in Row 1 column 7.
The multiplexed links are separated into three SPEs called SPE1, SPE2 and SPE3. Each envelope
carries up to 28 T1s, 21 E1, 28 TVT1.5s, 21 TVT2s, a DS3, an E3 or a Fractional link. SPE1
carries the T1s numbered 1,1 through 1,28, E1s numbered 1,1 through 1,21, DS3 number 1,1, E3
number 1,1 or Fractional link 1,1. SPE2 carries T1s numbered 2,1 through 2,28, E1s numbered
2,1 through 2,21, DS3 number 2,1, E3 number 2,1 or Fractional link 2,1. SPE3 carries T1s
numbered 3,1 through 3,28, E1s numbered 3,1 through 3,21, DS3 number 3,1, E3 number 3,1 or
Fractional link 3,1. TVT1.5s are numbered the same as T1 tributaries and TVT2s are numbered
the same as E1 tributaries.
SBSLITE™ Telecom Standard Product Data Sheet
Preliminary
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