Fdb Entry Types - Extreme Networks ExtremeWare XOS Guide Manual

Forwarding Database
You can enter and update entries using the command line interface (CLI).
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Certain static entries are added by the system upon switch boot-up.
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FDB Entry Types

FDB entries may be dynamic or static, and the entries may be permanent or non-permanent. The
following describes the types of entries that can exist in the FDB:
Dynamic entries—A dynamic entry is learned by the switch by examining packets to determine the
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source MAC address, VLAN, and port information. The switch then creates or updates an FDB entry
for that MAC address. Initially, all entries in the database are dynamic, except for certain entries
created by the switch at boot-up.
Entries in the database are removed (aged-out) if, after a period of time (aging time), the device has
not transmitted. This prevents the database from becoming full with obsolete entries by ensuring
that when a device is removed from the network, its entry is deleted from the database. Dynamic
entries are flushed and relearned (updated) when any of the following take place:
A VLAN is deleted.
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A VLAN identifier (VLANid) is changed.
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A port mode is changed (tagged/untagged).
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A port is deleted from a VLAN.
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A port is disabled.
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A port enters blocking state.
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A port goes down (link down).
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A non-permanent dynamic entry is initially created when the switch identifies a new source MAC
address that does not yet have an entry in the FDB. The entry may then be updated as the switch
continues to encounter the address in the packets it examines. These entries are identified by the "d"
flag in output.
show fdb
Dynamic entries age—that is, a dynamic entry is removed from the FDB (aged-out) if the device
does not transmit for a specified period of time (the aging time). This aging process prevents the
FDB from becoming full with obsolete entries by ensuring that when a device is removed from the
network, its entry is deleted from the database. The aging time is configurable. For more information
about setting the aging time, see
Static entries—A static entry does not age and does not get updated through the learning process. A
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static entry is maintained exactly as it was created. Conditions that cause dynamic entries to be
updated, such as VLAN or port configuration changes, do not affect static entries.
A locked static entry is an entry that was originally learned dynamically, but has been made static
(locked) using the MAC address lock-down feature. It is identified by the "s," "p," and "l" flags in
output and can be deleted using the
show fdb
Lock Down" on page 227
If the FDB entry aging time is set to zero, all entries in the database are considered static, non-aging
entries. This means that the entries do not age, but they are still deleted if the switch is reset.
NOTE
On the Aspen 8810 switch, if the same MAC address is detected on another virtual port that is not defined in the
static FDB entry for the MAC address, that address is handled as a blackhole entry.
ExtremeWare XOS 11.1 Concepts Guide
"Configuring the FDB Aging Time" on page
delete fdbentry
for more information about MAC address lock-down.
177.
command. See "MAC Address
176