This output indicates ARP throttle is enabled, filtering ARP packets according to the default packet threshold and
aging-time settings. ARP packets from a device identified as 000f20-aeaec0 are excluded from ARP throttling,
and statistics indicate 4 blacklisted clients and the ARP packet traffic of 180 clients being tracked.
switch# show ip arp-throttle
Source MAC Based ARP Attack Detection Information
Enabled : Yes
Remediation Mode : Filter
Threshold (pkt) : 30
Blacklist Age (sec) : 300
Excluded MAC List
-----------------
000f20-aeaec0
Clients in Blacklist : 4
Clients Being Tracked : 180
NOTE:
The “Clients in Blacklist” and “Clients being Tracked” counters shown above operate only when ARP
throttle is enabled. Rebooting the switch restarts the counters from zero. Executing any of the
following commands causes the switch to reset these counters to zero:
•
ip arp-throttle enable
(Starts the counters from zero.)
•
no ip arp-throttle enable
(Resets the counters to zero.)
•
ip arp-throttle remediation-mode <monitor | filter>
(Restarts the counters from zero if the
ip arp-throttle remediation-mode
setting is
changed.)
NOTE:
If a failover occurs on a 5400R switch, the switch maintains the blacklist status of any currently
blacklisted clients. However, the current list of tracked clients is cleared and restarted.
Identifying blacklisted and restored clients
The switch event log records an entry when
ip arp-throttle
blacklists a client, removes a client from the blacklist,
or drops an ARP packet received from a blacklisted client. Use the show logging command to display entries for
these actions.
Example
switch# show logging -r
Keys: W=Warning I=Information
M=Major D=Debug E=Error
---- Reverse event Log listing: Events Since Boot ----
W 02/16/16 22:57:16 02539 arpt: ST1-CMDR: Client 20fdf1-e0935b exceeds the limit of ARP packets and is blacklisted.
W 02/16/16 22:57:16 02541 arpt: ST1-CMDR: An ARP packet from blacklist client 20fdf1-e0935b is dropped. (4 times in 60 seconds)
W 02/16/16 22:57:03 02539 arpt: ST1-CMDR: Client d0bf9c-13c149 exceeds the limit of ARP packets and is blacklisted.
I 02/16/16 21:52:05 02540 arpt: ST1-CMDR: Client 20fdf1-e0935b is moved out of blacklist due to inactivity.
Chapter 5 Routing Basics
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