Planet Technology GSD-Series - Manual (Page 13)

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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 increasing 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.
The Ethernet 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