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JUNOS OS 10.4 Release Notes
102
MAC limiting—This feature is supported on SRX100, SRX210, SRX220, and SRX650
devices.
MAC limiting protects against flooding of the Ethernet switching table (also known as
the MAC forwarding table or Layer 2 forwarding table). You enable this feature on
interfaces (ports). MAC move limiting detects MAC movement and MAC spoofing on
access interfaces. You enable this feature on VLANs.
MAC limiting sets a limit on the number of MAC addresses that can be learned
dynamically on a single Layer 2 access interface or on all the Layer 2 access interfaces
on the switch.
You configure the maximum number of dynamic MAC addresses allowed per interface.
When the limit is exceeded, incoming packets with new MAC addresses are treated
as specified by the configuration.
You can choose to have one of the following actions performed when the limit of MAC
addresses or the limit of MAC moves is exceeded:
—Drop the packet and generate an alarm, an SNMP trap, or a system log entry.
drop
This is the default.
log
—Do not drop the packet but generate an alarm, an SNMP trap, or a system log
entry.
—Take no action.
none
shutdown
—Disable the interface and generate an alarm. If you have configured the
switch with the port-error-disable statement, the disabled interface recovers
automatically upon expiration of the specified disable timeout. If you have not
configured the switch for autorecovery from port error disabled conditions, you can
bring up the disabled interfaces by running the clear ethernet-switching port-error
command.
NOTE: MAC limit is only applied to new MAC learning requests. If you
already have 10 MACs learned and you configure the limit as 5, all the MACs
will remain in the FDB table. Once the MACs are cleared by the user (using
clear ethernet-switching table command), or they age out, they will not
be relearned.
MAC limit does not apply to static MACs. User can configure any number
of static MACs independent of MAC limit and all of them will be added to
FDB.
[Layer 2 Bridging and Switching Configuration Guide ]
Copyright © 2011, Juniper Networks, Inc.
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