TNETX15VE datasheet(82/113 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

PRINCIPLES OF OPERATION

VLAN and PORT find modifier bits (continued)

• If an address was found, perform a FINDNEXT port by:

• Setting PORT and NEXT bits in the findcontrol register. The TNETX15VE scans the lookup

table for the next address after the one contained in findnode. Since VLANs are port based, the

same MAC address cannot appear more than once on the same port.

• Waiting until the FNDCPLT interrupt is asserted, or poll findcontrol until the NEXT bit is cleared.

The PORT bit stays set.

• Reading the findcontrol register. If FOUND is set, the next address was found and the node’s

address and information are placed in the registers. If FOUND is not set, there are no more

addresses associated with this port.

• Repeat the FINDNEXT port command until no more nodes are found.

The VLAN bit is similar to the PORT bit in that it limits the FINDFIRST, FINDNEXT, and FIND commands to look

for only the addresses whose VLANID matches the VLAN contained in findVLANID. This command is useful

when management wants to know all addresses that are associated with a VLAN. This function returns both

unicasts and multicast addresses assigned to the VLAN. To dump addresses associated with VLAN 0x3, the

user must:

• Write a 0x03 to findVLANID.

• Perform a FINDFIRST VLAN command by:

• SettingtheVLANandFIRSTbitsinthefindcontrolregister.Nowritetofindnodeisrequired.The

TNETX15VE scans the lookup table for the first address that is associated with VLAN 0x3.

• Waiting until the FNDCPLT interrupt is asserted (or poll findcontrol) until the FIRST bit is

cleared. The VLAN bit stays set.

• Reading the findcontrol register. If FOUND is set, and an address was found, the node’s

address and information are placed in the registers. If FOUND is not set, there are no more

addresses associated with this VLAN.

• If an address is found, perform a FINDNEXT VLAN by:

• Setting the VLAN and NEXT bits in the findcontrol register. The TNETX15VE scans the lookup

table for the next address associated with the VLAN, starting with the address left in the

previous step.

• WaitinguntiltheFNDCPLTinterruptisasserted(orpollfindcontrol)untiltheNEXTbitiscleared.

The VLAN bit stays set.

• Reading the findcontrol register. If FOUND is set, and the next address was found, the node’s

address and information are placed in the registers. If FOUND is not set, there are no more

addresses associated with this VLAN.

• Repeat the FINDNEXT port command until no more nodes are found.

TNETX15VE Datasheet(PDF) 82 Page - Texas Instruments