Chapter 7: Switch operation
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NS3550-8T-2S Industrial Managed Switch User Manual
Chapter 7
Switch operation
Address table
The industrial 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 node in network, including MAC address, port number, etc. This information
comes from the learning process of the industrial managed switch.
Learning
When one packet comes in from any port, the industrial managed switch records the
source address, port number, and the other related information in the address table.
This information will be used to decide either forwarding or filtering for future packets.
Forwarding and filtering
When one packet comes from a port of the industrial managed switch, it checks the
destination address as well as the source address learning. The industrial 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 that this packet comes
from. These ports will transmit this packet to the network it is connected to. If found,
and the destination address is located at a different port from the one this packet
comes from, the industrial 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 that this packet comes in, then this
packet will be filtered, thereby increasing the network throughput and availability.
Store-and-forward
Store-and-Forward is a packet-forwarding technique. A Store-and-Forward switch
stores the incoming frame in an internal buffer and completes error checking before
transmission. Therefore, no erroneous packets will occur, making it the best choice
when a network needs efficiency and stability.
