Forwarding Database (Fdb); Introduction; Mac-Table Entry Types - Nokia ESB26 User Manual

11. Forwarding Database (FDB)

Introduction

The MAC Address table contains the information that is in the forwarding database. The
switch uses the forwarding database to forward packets to the appropriate bridge in the bridge
group.
The FDB has both static entries, which are created by the user, and dynamic entries (learned
entries), which are added and removed by the learning process. Static entries cannot be
overwritten by the learning process, and are removed from the table only when you explicitly
delete them.

MAC-Table Entry Types

There are several types of entries in the FDB (forwarding Database Table):
Dynamic entries −Initially, all entries in the database are dynamic. Entries in
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the database are removed (aged-out) if, after a period of time (aging time), the
device has not transmitted. If a device is removed from the network, its entry
is deleted from the database. In this way, the database is not filled up with
obsolete entries. If the switch is reset or a power Off/On cycle occurs,
dynamic entries are deleted from the database. The dynamic entries can also
be deleted by a specified command. More information about setting the aging
time and deleting dynamic entries is provided further on in this section.
Static entries − Static entries are configured by the user. These are
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permanent entries which are retained in the database if the switch is reset or a
power off/on cycle occurs. The system administrator is responsible for
making entries permanent. A permanent entry can be a unicast MAC address.
All entries entered by way of the command-line interface are stored as
permanent.
Secure entries −A secure entry is configured to a secured port (configured by
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the port security command as described in the Port Security chapter),
allowing only secured MAC addresses to be learned by this port.
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Self entries – A self entry is created automatically for each VLAN that is
configured on the switch with the switch's MAC address.
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Filtered entries –Filtered entries are dynamic MAC addresses that perform
security violation on secured port (configured by the port security
command).
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