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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 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 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
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 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 comes in, then this packet will be filtered. Thereby increasing
the network throughput and availability.
