Cisco Catalyst 4500 Series, Software Configuration Manual

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Catalyst 4500 Series Switch, Cisco IOS Software Configuration Guide - Cisco IOS XE 3.9.xE and IOS 15.2(5)Ex
Chapter 58 Configuring Dynamic ARP Inspection
Configuring Dynamic ARP Inspection
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SwitchA# show ip arp inspection statistics vlan 100
Vlan Forwarded Dropped DHCP Drops ACL Drops
---- --------- ------- ---------- ---------
100 15 169 160 9
Vlan DHCP Permits ACL Permits Source MAC Failures
---- ------------ ----------- -------------------
100 0 0 0
Vlan Dest MAC Failures IP Validation Failures Invalid Protocol Data
---- ----------------- ---------------------- ---------------------
100 0 0 0
SwitchA#
Configuring the Log Buffer
When the switch drops a packet, it places an entry in the log buffer and then generates system messages
on a rate-controlled basis. After the message is generated, the switch clears the entry from the log buffer.
Each log entry contains flow information, such as the receiving VLAN, the port number, the source and
destination IP addresses, and the source and destination MAC addresses.
A log-buffer entry can represent more than one packet. For example, if an interface receives many
packets on the same VLAN with the same ARP parameters, the switch combines the packets as one entry
in the log buffer and generates a single system message for the entry.
If the log buffer overflows, it means that a log event does not fit into the log buffer, and the display for
the
show ip arp inspection log privileged EXEC command is affected. No other statistics are provided
for the entry.