Access RAD ASMi-54 Installation And Operation Manual page 24

Chapter 1 Introduction
The ASMi-54 VLAN-Aware bridge is an Independent VLAN Learning (IVL) bridge.
The learning process inserts a new dynamic entry into the MAC table. This entry
consists of a MAC-VID pair and bridge port.
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Aging Process
The aging process checks the forwarding MAC table periodically. Each dynamic
entry-aging period that has exceeded the configured Aging Time Limit is deleted.
The aging period represents the time passed since the last frame for this entry
entered the bridge. The periodic check of the MAC table (aging time intervals)
results in the actual aging time that can reach up to twice the value that was
configured by the user.
Forwarding Process
The forwarding process is performed based on the frame destination MAC VID
pair. The frame is forwarded to the bridge port that was specified in the MAC
table for this MAC VID pair entry.
Untagged frames are forwarded according to the PVID that was attached to that
frame during the ingress process.
Frames are forwarded, dropped, or flooded according to the following guidelines:
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Transmission Process
After the forwarding process identifies the destination bridge port/ports to which
the frames must be transmitted, the frames are transmitted in the appropriate
format.
1-8 Functional Description
If the MAC-VID pair already exists for the same port, the aging time is
updated
If the MAC-VID pair already exists but for a different bridge port (dynamic
entry), the new entry overrides the existing one
If the MAC-VID pair already exists for a different bridge port (static entry), the
static entry prevails.
Forwarded: If the bridge port of the pair entry (DA, VID) in the MAC table is
both an active bridge port and a member of the VLAN, the frame is forwarded
to that bridge port only.
Dropped:
If the bridge port for the pair entry (DA, VID) in the MAC table is the port
on which the frame was received, the frame is dropped.
If there are no active ports associated with the frame's VID, or if the VID
is not defined at all, the frame is dropped.
Flooded:
If the pair (DA, VID) is not learned and does not exist in the MAC table,
the frame is transmitted to all bridge ports that are associated with the
frame's VLAN ID.
Multicasts and broadcasts are flooded only through the bridge ports
whose VLAN ID is identical to the frame's VLAN ID.
Installation and Operation Manual
ASMi-54 Ver. 1.0