D-Link DWS-1008 User Manual
Managing the Layer 2 Forwarding Database
A DWS-1008 switch uses a Layer 2 forwarding database (FDB) to forward traffic within a VLAN. The
entries in the forwarding database map MAC addresses to the physical or virtual ports connected to
those MAC addresses within a particular VLAN. To forward a packet to another device in a VLAN, the
switch searches the forwarding database for the packet’s destination MAC address, then forwards the
packet out the port associated with the MAC address.
Types of Forwarding Database Entries
The forwarding database can contain the following types of entries:
Dynamic - A dynamic entry is a temporary entry that remains in the database only until the entry
is no longer used. By default, a dynamic entry ages out if it remains unused for 300 seconds (5
minutes). All dynamic entries are removed if the switch is powered down or rebooted.
Static - A static entry does not age out, regardless of how often the entry is used. However, like
dynamic entries, static entries are removed if the switch is powered down or rebooted.
Permanent - A permanent entry does not age out, regardless of how often the entry is used. In
addition, a permanent entry remains in the forwarding database even following a reboot or power
cycle.
How Entries Enter the Forwarding Database
An entry enters the forwarding database in one of the following ways:
Learned from traffic received by the switch - When the switch receives a packet, the switch
adds the packet’s source MAC address to the forwarding database if the database does not
already contain an entry for that MAC address.
Added by the system administrator - You can add static and permanent unicast entries to the
forwarding database. (You cannot add a multicast or broadcast address as a permanent or static
forwarding database entry.)
Added by the switch itself - For example, the authentication protocols can add entries for wired
and wireless authentication users. The switch also adds any static entries added by the system
administrator and saved in the configuration file.
Summary of Contents for DWS-1008
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