PLANET FSD-1605 - Manual (Page 11)


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 increase 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 servers directly to the network, thereby increasing throughput and
availability. However, the switch is most commonly used to segment existing
hubs, which nearly always improves overall performance. An Ethernet
Switching can be easily configured in any Ethernet network environment to
significantly boost bandwidth using conventional cabling and adapters.