t71l6808a TM Technology Inc., t71l6808a Datasheet - Page 6

• Manufacturer Part Number: t71l6808a
• Description: Octal 10/100 Switch With Embedded Memory
• Manufacturer: TM Technology Inc.

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Preliminary T71L6808A
If the destination address is not found in the address table, the T71L6808A treats the packet as a
broadcast packet and forwards the packet to the other ports.
If the port monitoring function is enabled, the packet forwarding decision is also subject to the port
monitoring configurations.
If the first bit of the destination address is a “1,” the packet will be handled as a multicast or
broadcast frame. The destination ports of the broadcast packet are all ports within the same VLAN
except the source port itself.
The T71L6808A automatically learns the port number of attached network devices by examining
the source MAC address of all incoming packets. If the source address is not found in the address
table, the switch IC adds it to the table.
Address Learning
TheT71L6808A provides an on-chip 1K MAC Address-to-PortID table for the frame destination
look-up operations. It uses a hashing algorithm to learn the MAC address. The T71L6808A
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for the source address (SA) of an incoming packet in the address table and acts as follows : If the
SA was not found in the address table(a new address), the T71L6808A waits until the end of the
packet (no-error packet) and updates the address table. If the SA was found in the address table,
then aging value of each corresponding entry will be reset to 0.
The Individual MAC Address is a 48-bit unique MAC address to be programmed or learned. Bit 0
of a SA will be masked, i.e. no multicast SA.
When the DA is PAUSE command, then the learning process will be disabled automatically by
T71L6808A.
Address Aging
If the SA aging option is enabled, the learned SA will be cleared if it is not refreshed within the 300
seconds.
Broadcast Storm Control
The T71L6808A supports broadcast storm control on a per-port basis.
Broadcast packets will be
forwarded to all ports except the source port and thus will use too much of the switch resources
Taiwan Memory Technology, Inc. reserves the right
P. 6
Publication Date:May. 2001
to change products or specifications without notice.
Revision:0.A