DS92UT16 datasheet(8/111 Pages) TI1

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OBSOLETE

DS92UT16

SNOS992E – JANUARY 2002 – REVISED APRIL 2013

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The PDU fields are configured as shown in Table 1. The total PDU cell length must be in the range of 52 to 64

bytes. In addition, variable length fields must be programmed to an even number of bytes because the

DS92UT16 operates with an internal 16 bit data path. The total number of bytes defined for User Prepend plus

UDF1/2 and User Append must not exceed 12 bytes to maintain the maximum PDU cell length of 64 bytes.

Table 1. PDU Cell Format Options

Fixed/

Field

Bytes

Variable

User Prepend

Variable

0, 2, 4, 6, 8, 10, 12

Cell Header

Fixed

UDF1/2

Variable

2, 0 in 16 bit mode

(On/Off)

1, 0 in 8 bit mode

Payload

Fixed

User Append

Variable

0, 2, 4, 6, 8, 10, 12

Although the UDF1/2 bytes will always be present, the DS92UT16 can be programmed to either transport these

bytes or ignore them. If they are to be ignored, then the TCS strips them out in the down-bridge direction and the

UTOPIA up-bridge section inserts a HEC byte in UDF 1. Otherwise, they can be transported transparently the

same as any other PDU byte.

Figure 6. PDU and Link Transport Container Format

Each link TC has an MPHY address byte, two Flow Control (F) Channel bytes, and a HEC byte in addition to the

PDU cell. The two F1 and F2 bytes per TC constitute the F Channel, which is used for flow control and OAM

purposes over the link. The TCS uses the HEC byte for container delineation, frame delineation, and cell header

error detection.

MPHY Tagging and Routing

In the down-bridge direction, the DS92UT16 adds an additional byte (MPHY byte) to each PDU. It contains the

MPHY port address associated with that PDU, as shown in Table 2.

Table 2. MPHY Byte

Bit

Function

MPHY Port Address 0–31

Reserved

At the other end of the link, this byte is used to route the incoming PDU from the LVDS interface to the

appropriate MPHY port queue.

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