TNETX15VE datasheet(4/113 Pages) TI1

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TNETX15VE

VLAN-ENGINE ADDRESS-LOOKUP DEVICE

SPWS028B – APRIL 1997 – REVISED SEPTEMBER 1997

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

general description

bus watcher

The bus watcher interfaces to the TNETX3150/TNETX3150A DRAM interface and extracts destination, source

addresses, VLAN information, and the originating port number. The bus watcher is responsible for identifying

the frame’s start-of-frame and end-of-frame tags. It also interfaces to the arbiter and the TNETX15VE logic to

perform off-the-wire address LOOKUPs and ADDs.

DIO interface

The DIO interface enables an attached microprocessor to access the TNETX15VE internal registers. The DIO

interface is used to select control modes, read statistics, receive interrupts, read/write to attached MII devices,

read/write to an attached EEPROM, and perform management LOOKUPs, ADDs, and DELETEs.

EEPROM interface

The EEPROM interface allows accesses to the EEPROM. It also interfaces with the EEPROM for automatic

loading of selected registers from the EEPROM at startup or reset.

arbiter

The arbiter manages the SRAM access for the TNETX15VE logic operations by assigning priorities to the logic

operations. Wire lookups have the highest priority, followed by DELETEs, ADDs, management LOOKUPs, and

AGEs. The individual logic operations request the bus by asserting a request signal. The arbiter grants the

SRAM bus by controlling the SRAM-bus address/data multiplexer.

SRAM address/data multiplexer (MUX)

The address/data MUX is controlled by the arbiter and selects the logic operation that has ownership of the

SRAM bus.

TNETX15VE logic operations

The TNETX15VE logic operations consist of LOOKUP, DELETE, ADD, FIND, and AGE operations. Each logic

operation is assigned a priority on the SRAM bus and is controlled by the arbiter. The LOOKUP operation has

the highest priority and is responsible for wire lookups. The DELETE operation is responsible for either deletes

from the AGE operation or for management-delete requests. The ADD operation is responsible for wire adds

as well as for management-add requests. The FIND operation is responsible for management searches of the

lookup table. The AGE operation is responsible for deleting addresses that have no activity in a fixed time period.

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