Planet ISW-511 Series, Руководство пользователя

Страница: 27 / 32

27
4. Switch Operation
4.1 Address Table
The Industrial Fast Ethernet 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 the network,
including MAC address, port no., etc. This information comes from the
learning process of Industrial Fast Ethernet Switch.
4.2 Learning
When one packet comes from any port of Industrial Fast Ethernet
switch, the Industrial Fast Ethernet 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.
4.3 Forwarding & Filtering
When one packet comes from some port of the Industrial Fast Ethernet
Switch, it will also check the destination address besides the source
address learning. The Industrial Fast Ethernet 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 where this packet
comes in. And these ports will transmit this packet to the network if
connected. If found and the destination address is located at a different
port from this packet comes in, the Industrial Fast Ethernet 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 where this packet
comes in, then this packet will be filtered.