TNETX3150A datasheet(34/78 Pages) TI

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TNETX15AE

ADDRESS-LOOKUP DEVICE

SPWS041A – AUGUST 1997 – REVISED OCTOBER 1997

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

uplink routing register, uplinkport at 0x6E (DIO)

BIT

Reserved

Uplink

Initial values after reset

The uplinkport register routes selected packets to a user-selected port. This register is valid only when the

destination address being looked up has the CUPLNK bit set. Then the TNETX15AE forwards frames to the

port specified in the lookup table and the port specified in this register. The TNETX15AE masks (does not send

frames to) the port that originated the frame.

PRINCIPLES OF OPERATION

The purpose of this section is to assist in the development of management operational code for the TNETX15AE.

Management code is drastically simplified when using the TNETX15AE since it is designed to operate without the

need for a management CPU. Many of the functions that were performed previously by a CPU are now integrated

on the TNETX15AE.

This section discusses the following topics:

D A background on the TNETX15AE architecture, including the data-storage algorithm and the arbitration

between logic operations

D How to access the TNETX15AE registers through the DIO interface, and how these registers can be used

to access the internal/external SRAM, the EEPROM, and any MII-managed devices

D How to access the TNETX15AE through the DIO interface from a hardware reset, and do the steps needed

to bring the TNETX15AE to an operational state

D How to use the logic operations to perform management-based lookups, adds, and deletions.

D How to use the TNETX15AE interrupt support to create event-driven management code.

internal operation

This section describes the TNETX15AE hardware and how it affects the programmer and the

TNETX3150/TNETX3150A/TNETX3100 performance. The functionality described in this section is transparent

to the user, but it is included to help the user become familiar with the TNETX15AE architecture and how it

interfaces

the

TNETX3150/TNETX3150A/TNETX3100

device.

Refer

the

latest

TNETX3150/TNETX3150A/TNETX3100 documentation for additional information.

EAM codings and in-order broadcasts (IOB)

The TNETX15AE uses two styles of EAM codings – single-port and multiple-port codings. The

TNETX3150/TNETX3150A/TNETX3100 treats these two types of coding differently.

Single-port codings forward frames to a single port. The TNETX3150/TNETX3150A/TNETX3100 queues these

frames to the port queue.

Multiple-port codings forward frames to multiple ports. The TNETX3150/TNETX3150A/TNETX3100 creates an

IOB list structure to queue this frame to multiple-port queues. IOB lists use more memory bandwidth than a

regular list because IOB lists require the use of an extra 64-byte buffer to contain all queue pointers for the ports.

many

small

frames

are

sent

multiple

ports,

IOB

structures

then

can

use

significant

TNETX3150/TNETX3150A/TNETX3100 memory bandwidth.

TNETX3150A 数据表(PDF) 34 Page - Texas Instruments

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