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4. Switch Operation
4.1 Address Table
The Industrial Gigabit Ethernet Switch is implemented with an address
table. This address table is 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 Industrial Gigabit Ethernet Switch.
4.2 Learning
When one packet comes in from any port, the Industrial Gigabit
Ethernet Switch will record the source address, port no, and the other
related information in the address table. This information will be used
to decide either forwarding or filtering for future packets.
4.3 Forwarding & Filtering
When one packet comes from some port of the Industrial Gigabit
Ethernet Switch, it will also check the destination address besides the
source address learning. The Industrial Gigabit Ethernet Switch will
look up 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 a different port from this packet that comes in, the
Industrial Gigabit Ethernet Switch 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, then this packet will be filtered; thereby
increasing the network throughput and availability.
4.4 Store-and-Forward
Store-and-Forward is one type of packet-forwarding techniques.
A Store-and-Forward Industrial Gigabit Ethernet Switch stores the
incoming frame in an internal buffer and does the complete error
