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3. SWITCH OPERATION
3.1 Address Table
The Switch is implemented with an address table. This address table
composed of many entries. Each entry is used to store the address
information of some node in network, including MAC address, port
no, etc. This information comes from the learning process of Ethernet
Switch.
3.2 Learning
When one packet comes in from any port, the Switch will record the
source address, port no. And the other related information in address
table. This information will be used to decide either forwarding or
filtering for future packets.
3.3 Forwarding & Filtering
When one packet comes from some port of the Ethernet Switching,
it will also check the destination address besides the source address
learning. The Ethernet Switching will lookup the address-table for the
destination address. If not found, this packet will be forwarded to all
the other ports except the port, which this packet comes in. And these
ports will transmit this packet to the network it connected. If found,
and the destination address is located at different port from this packet
comes in, the Ethernet Switching will forward this packet to the port
where this destination address is located according to the information
from address table. But, if the destination address is located at the
same port with this packet comes in, then this packet will be filtered.
Thereby increase the network throughput and availability.
3.4 Store-and-Forward
Store-and-Forward is one type of packet-forwarding techniques. A
Store-and-Forward Ethernet Switching stores the incoming frame in
an internal buffer, do the complete error checking before transmission.
Therefore, no error packets occurrence, it is the best choice when a
network needs efficiency and stability.
