Switch Operation; Address Table; Learning; Forwarding & Filtering - Planet ISW-504PT User Manual

4. Switch Operation

4.1 Address Table

The Industrial Fast 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. and etc. This information comes from the
learning process of Industrial Fast Ethernet Switch.

4.2 Learning

When one packet comes from any port of Industrial Fast Ethernet
switch, the Industrial Fast 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 Fast Ethernet
Switch, it will also check the destination address besides the source
address learning. The Industrial Fast 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 Fast 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.
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