Planet Technology FGSW-2620VM - Manual (Page 69)

FGSW-2620VM User’s Manual
5. SWITCH OPERATION
5.1 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.
5.2 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.
5.3 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.
5.4 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.
Due to the learning function of the Ethernet switching, the source address and corresponding port number of each
incoming and outgoing packet are stored in a routing table. This information is subsequently used to filter packets
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