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96 CHAPTER 5: CONFIGURING AND MANAGING PORTS AND VLANS
Managing the Layer
A WX 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 WX 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
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 WX switch is powered down or
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 WX 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
An entry enters the forwarding database in one of the following ways:
Learned from traffic received by the WX switch — When the WX
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 WX switch itself — For example, the authentication
protocols can add entries for wired and wireless authentication users.
The WX switch also adds any static entries added by the system
administrator and saved in the configuration file.