354 ExtremeWare Software 7.3.0 Command Reference Guide
FDB Commands
clear fdb
clear fdb {<mac_address> | blackhole | ports <portlist> | remap | vlan
<vlan name>}
Description
Clears dynamic FDB entries that match the filter.
Syntax Description
Default
Clears all dynamic FDB entries.
Usage Guidelines
This command clears FDB entries based on the specified criteria. When no options are specified, the
command clears all dynamic FDB entries.
The system health checker also checks the integrity of the FDB. If you enable the system health checker,
a section of the FDB memory on each module’s switching fabric is non-intrusively compared to the
software copy of the FDB. The switch takes one of the following actions if it detects a bad entry:
• If the entry is not in use—remaps around the entry location
• If the entry is in use, but is safely removable (most MAC and IP-DA entries)—removes the
questionable entry, allows the table to be rebuilt naturally, and remaps around the entry location
• If the entry is in use and is not safely removable (MAC_NH, IPSA, IPMCDA, IPDP, IPSP,
IPXSN)—sends a warning message to the log
If the switch detects more than eight questionable entries, it executes the configured failure action and
stops remapping on the switch fabric. To see the questionable and remapped entries, use the
show fdb
command. The following information is displayed:
• Questionable entries are marked with a “Q” flag
• Remapped entries are marked with an “R” flag
• Total FDB count
You can also display FDB scan statistics using the following command:
show diagnostics sys-health-check
Example
The following command clears any FDB entries associated with ports 3-5:
clear fdb ports 3-5
mac_address Specifies a MAC address, using colon-separated bytes.
blackhole Specifies the blackhole entries.
portlist Specifies one or more ports. May be in the form 1, 2, 3-5, 2:*, 2:5, 2:6-2:8.
remap Clears the remapped and questionable FDB entries.
vlan name Specifies a VLAN name.
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