Alcatel Speed Touch Wireless User Manual page 71

Learning
Aging
Learning and Aging
Flooding
3EC 17766 AAAA TCZZA Ed. 01
If the bridge is turned on, the filtering database is empty. Over
time it is filled with entries via the learning mechanism.
Ethernet frames arriving on any port are inspected for their source
MAC address and put into the filtering database together with the
port ID the frames arrived on.
Through this knowledge, it is able to keep traffic submitted to your
local printer from crossing the bridge. Yet it allows frames
belonging to sessions with remote machines to pass over the ADSL
line.
Entries are aged, i.e. removed from the filtering database, after a
certain time has elapsed (Aging time).
The learning and aging process make the bridge Plug & Play. Both
keep the filtering database up to date with the current network
configuration.
Example: Suppose a PC NIC is replaced, the old MAC address is
aged (and will be consequently discarded), while a new MAC
address will be learned.
If an Ethernet frame arrives, the destination MAC address is
searched for in the filtering database. If the destination MAC
address is not found (implying it is not yet learned), it is forwarded
to all ports in the forwarding state, except the one the frame
arrived on.
Note: Broadcast and multicast MAC addresses are always
flooded.
5 Data Services - Transparent Bridging
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