TNETX15VE datasheet(30/113 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

lookup table search control register, findcontrol at 0x16 (DIO)

The management logic uses the findcontrol register to scan the lookup table for addresses. Five commands

are available: findfirst (FIRST), findnext (NEXT), findnew (NEW), find (LKUP), and findFIFO (NBFR). Variations

on these commands can be achieved by the use of the PORT and VLAN modifier bits for all find commands

except findFIFO and find. Only one command is valid at one time. Example: a findfirst and a findnext command

cannot be issued at the same time (0x06). The TNETX15VE ignores all multiple commands. This register is a

read/write register. When the FIND logic is operating, this register is locked and writes are ignored, allowing the

DIO cycle to complete. The bits remain as written while running. Polling this register or using a FNDCPLT

interrupt determines the completeness of the find command (if the find command is complete, the bits used to

start the command execution are cleared). The PORT and VLAN modifiers can be used at the same time to

increase the pool of available match candidates.

BIT

FOUND

NEW

NBFR

PORT

VLAN

FIRST

LKUP

Initial Values After Reset

BIT

NAME

FUNCTION

FOUND

Address found. If the address contained in the findnode register is found in the table, FOUND is asserted.

The data contained in the find interface (findVLANID, findnode, findport, and findnodeage) is valid only when

this bit is 1. This is a read-only bit.

NEW

New address finds. When NEW is 1, the TNETX15VE scans the address table for the first address, which

is marked as NEW. After successful finds, the NEW flag is cleared. All searches for addresses with the NEW

bit set start at the beginning of the table.

NBFR

Nonblocked FIFO read. Setting the NBFR bit requests information from the top of the NBLOCK FIFO (if

present). If there is an entry in the FIFO, the information is returned in the findnode and findport locations,

and the FOUND bit is set to 1. If there is not an entry in the FIFO, the FOUND bit is set to 0. The NBFR bit

stays set until the command finishes. There is an interrupt available to signal when the NBLCK FIFO is not

empty and should be searched with this command bit.

PORT

Find modifier – find by port. PORT is used with the FIRST, NEXT, NEW, and LKUP bits to find the unicast

address whose port assignment matches the port contained in the portcode field of the findport register.

VLAN

Find modifier – find by VLAN ID. VLAN is used with the FIRST, NEXT, NEW, and LKUP bits to find addresses

whose VLAN ID matches the VLAN ID contained in the findVLANID register.

FIRST

Lookup first address. When FIRST is 1, the TNETX15VE scans the address table for the first valid address.

It returns this address to the findnode register.

Lookup next addresses. When asserted, the TNETX15VE scans the address table for the next available

address after the address currently in the findnode registers (0xC–0x11). It returns this next address to the

findnode register.

LKUP

Address lookup. When asserted, the TNETX15VE scans the address table for the address contained in the

findnode register. If found, the FOUND bit reads 1; if not found, it reads 0.

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