D-Link DES-3326 User Manual - Mac Address Aging Time
DES-3326 Layer 3 Fast Ethernet Switch User’s Guide
36
Switch Management and Operating Concepts
receives a packet destined for a station on Port 2, the Switch
transmits that packet through Port 2 only, and transmits nothing
through the other ports. This process is referred to as ‘learning’
the network topology.
MAC Address Aging Time
The Aging Time affects the learning process of the Switch.
Dynamic forwarding table entries, which are made up of the source
and destination MAC addresses and their associated port numbers,
are deleted from the table if they are not accessed within the aging
time.
The aging time can be from 10 to 1,000,000 seconds with a default
value of 300 seconds. A very long aging time can result in dynamic
forwarding table entries that are out-of-date or no longer exist.
This may cause incorrect packet forwarding decisions by the
switch.
If the Aging Time is too short however, many entries may be aged
out too soon. This will result in a high percentage of received
packets whose source addresses cannot be found in the forwarding
table, in which case the switch will broadcast the packet to all
ports, negating many of the benefits of having a switch.
Static forwarding entries are not affected by the aging time.
Filtering
The switch uses a filtering database to segment the network
and control communication between segments. It can also filter
packets off the network for intrusion control. Static filtering
entries can be made by MAC Address or IP Address filtering.