Planet Technology WGS3-2620 - Manual (Page 236)

WGS3 Layer 3 Switch User’s Manual - 228 -
Chapter 6.Advanced Topics
This Layer 3 switch supports both Layer 2 which is based on physical device addresses and Layer 3
switching which is based on IP network addresses. These functions, along with other advanced features
are described in this chapter.
6.1 Layer 2 Switching
When a frame enters a port, its destination MAC address is checked in the address database to see
which port leads to this destination. If the destination address belongs to the incoming port, the frame is
dropped or “filtered.” If the destination port is found on another port, the frame is forwarded to that port
and queued for output. But, if the destination address is not found in the address database, the frame is
sent to one or more output ports based on the rules for handling tagged or untagged VLAN frames.
If the source MAC address of the frame was not found in the address database, it is recorded along with
the incoming port number where it entered the switch. This information is then used to make later
decisions for frame forwarding.
During switching, the switch performs multiple steps, including:
• VLAN Classification
• Learning
• Filtering
• Forwarding
• Aging
The following sections provide additional information about the tasks the switch performs during unicast
and multicast switching.