Switch Operation; Address Table; Learning; Forwarding & Filtering - Planet GS-5220 Series User Manual

User's Manual of GS-5220 LCD Series

5. SWITCH OPERATION

5.1 Address Table

The Managed 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 Managed Switch.

5.2 Learning

When one packet comes in from any port, the Managed 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 Managed Switch, it will also check the destination address
besides the source address learning. The Managed 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 comes in, the Managed 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,
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 Managed Switch stores
the incoming frame in an internal buffer and do the complete error checking before transmission. Therefore, no
error packets occur; it is the best choice when a network needs efficiency and stability.
The Managed 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 existence hubs, which nearly always improves the overall
performance. An Ethernet switching can be easily configured in any Ethernet network environment to
significantly boost bandwidth using the conventional cabling and adapters.
538