T71L6816A Taiwan Memory Technology, T71L6816A Datasheet - Page 7

• Manufacturer Part Number: T71L6816A
• Description: Sixteen-port 10/100 Switch
• Manufacturer: Taiwan Memory Technology

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3.5.1 Unicast Forwarding
If the first bit of the DA is “0”, the packet is regarded as an unicast packet and the
ARL will use the DA as an key to search for a matched entry in address table by either
hashing algorithm or direct mapping method chosen by the configuration from EEPROM.
If an matched entry is found, the ARL will return a destination port number. If the port
number returned is within the same VLAN group but not the same of incoming port, the packet
will be forwarded to the destination port, otherwise it will be discarded. Also, if the
trunking scheme is enabled and the returned port is defined as a member of trunking group,
the real output port could be any one of the trunking ports and is dependent on trunking
scheme currently used.
If ARL can’t find any entry matched in address table, the packet will be regarded as an
broadcast packet and forwarded to other ports that belong to the same VLAN group of
the incoming port.
3.5.2 Multicast Forwarding
If the first bit of the DA is “1”, the packet is regarded as a multicast packet. The packet
will be forwarded to other ports that belong to the same VLAN group of the incoming port.
3.6 Data Transmission
According to the standard of IEEE 802.3, the T71L6816A will transmit all output packets
with a guaranteed minimum IPG(Inter Packet/Frame Gap) of 96BT(bit time) even if the
incoming packets have an IPG l ess than 96BT. However, the T71L6816A will drop excess
incoming packets which input continuously with smaller IPG than 96BT due to run out of
packet buffer and result in the packet loss. The 96BT should be 96ns for 10Mbps and 960ns
for 100Mbps.
During the transmit process, the T71L6816A will read the packet data from SSRAM and forward
it to the PHY device of the destination port in di-bit format. Also, the T71L6816A will
generate seven bytes of preamble(10101010) and SFD(10101011) prior to the frame data
followed by four bytes of FCS generated by T71L6816A automatically.
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Change to products or specifications without notice.
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Preliminary T71L6816A
Publication Date:Jun. 2001
Revision:0.A