PLANET IGS-504HPT - Manual (Page 29)

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4. Switch Operation
4.1 Address Table
The Industrial Gigabit PoE+ 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 nodes in the network, including MAC address, port
no., etc. This information comes from the learning process of Industrial Gigabit
PoE+ Switch.
4.2 Learning
When one packet comes from any port, the Industrial Gigabit PoE+ Switch will
record the source address, port number 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 ports of the Industrial Gigabit PoE+ Switch,
it will also check the destination address besides the source address learning. The
Industrial Gigabit PoE+ 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 PoE+ 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 that comes in, 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 PoE+ Switch stores the incoming frame in an internal
buffer and does the complete error checking before transmission. Therefore, no
error packets occur. It is the best choice when a network needs efficiency and
stability.
The Industrial Gigabit PoE+ Switch scans the destination address from the packet-
header, searches the routing table provided for the incoming port and forwards
the packet, only if required. The fast forwarding makes the switch attractive for
connecting servers directly to the network, thereby increasing throughput and