TNETX15VE datasheet(22/113 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

age-deletion time-select register, agingtimer at 0x02–0x03 (DIO)

BYTE 1

BYTE 0

BIT

Agingtimer

Initial Values After Reset

The agingtimer register is 16 bits wide and is used to control the aging process. There are two aging modes,

and the modes are selected according to the value of this register:

• When agingtimer is 0 or 0xFFFF, the TNETX15VE performs table-full aging. TNETX15VE ages out the

oldest address (only when the lookup table becomes full).

• When agingtimer is not 0 or 0xFFFF, the TNETX15VE performs threshold aging. The value in the

Agingtimer is the time threshold in seconds. All addresses that are older than this time are aged out.

Aging does not delete addresses that have been secured, and multicast addresses also are not aged. Aging

is disabled when the NAUTO bit in the control register is set. It is management’s responsibility in NAUTO mode

to manage the lookup table.

All bits in this register are read/writeable and default to 0x0 during reset. This field also is automatically loaded

from the EEPROM when the RESET terminal is asserted low, when the DIO address high register contains 0x40

or when LOAD in the control register is set to 1.

learning-disable register, NLRNports at 0x04–0x05 (DIO)

BYTE 1

BYTE 0

BIT

Reserved

NLRNports

Initial Values After Reset

The NLRNports register disables learning for the ports whose corresponding bit is 1. Frames are still received

and routed but they cause no additions to the lookup table. This register is automatically loaded from the

EEPROM in a hardware reset (RESET = 0 or when the DIO address-high register contains 0x40) or when the

LOAD bit in the control register is set. It is read/write at any time.

TNETX15VE 数据表(PDF) 22 Page - Texas Instruments