Learning Process Introduction
4-3
Software Reference for SwitchBlade x3100 Series Switches (Layer Two Switching)
If the frame's source address is not already in the Forwarding Database for the VLAN, the address is added
(MAC address and VLAN ID) and an ageing timer for that entry is started. If the frame's source address is
already in the Forwarding Database, the ageing timer for that entry is restarted.
By default, switch learning is enabled, and it can be disabled or enabled using the commands:
DISABLE SWITCH LEARNING
ENABLE SWITCH LEARNING
Caution: If the Learning Process is disabled, MAC addresses are no longer added to the forwarding database,
and as the ageingtimer (discussed next) expires and frames with their source addresses and VLAN
IDs are no longer learned, the system will slowly depopulate its forwarding database
If the ageing timer for an entry in the Forwarding Database expires before another frame with the same source
address and VID is received, the entry is removed from the Forwarding Database. This prevents the Forwarding
Database from being filled up with information about hosts that are inactive or have been disconnected from the
network, while ensuring that entries for active hosts are kept alive. By default, the ageing timer is enabled, and it
can be disabled or enabled using the commands
ENABLE SWITCH AGEINGTIMER
DISABLE SWITCH AGEINGTIMER
The ageing timer can be modified and has a range of 10 - 630 seconds. By default, the ageing time is set to a
value of 300 second (5 minutes).
The Forwarding Database relates a host's (source) address to a port on the switch, and is used by the switch to
determine from which port (if any) to transmit frames with a destination MAC address matching the entry in
the host map.
To display the contents of the Forwarding Database, use the SHOW SWITCH FDB command. The output
includes:
• VLAN or HVLAN - The VID Identifier for the VLAN or HVLAN.
• Interface - The interface from which the MAC address was learned.
• MAC Address - The MAC address as learned from the source address field of a frame. Example:
00:0C:25:00:13:8C.
• Status - Whether the MAC address was learned from the source address field of a frame.
manager SEC>> show switch fdb interface 0.1
--- Switch Forwarding Database ---
Slot VLAN Interface ID MAC Address Status
----------- ----------- --------------- ---------------------- --------
0 1 0.1 00:58:F8:3F:8F:9F Dynamic
0 1 0.1 04:6D:D6:B6:16:BA Dynamic
0 1 0.1 06:46:69:F9:38:9D Dynamic
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