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Cisco Catalyst Blade Switch 3130 and 3032 for Dell Software Configuration Guide
OL-12247-04
Chapter 23 Configuring Dynamic ARP Inspection
Configuring Dynamic ARP Inspection
Beginning in privileged EXEC mode, follow these steps to perform specific checks on incoming ARP
packets. This procedure is optional.
To disable checking, use the
no ip arp inspection validate
[
src-mac
] [
dst-mac
] [
ip
] global
configuration command. To display statistics for forwarded, dropped, and MAC and IP validation failure
packets, use the
show ip arp inspection statistics
privileged EXEC command.
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.
Command
Purpose
Step 1
configure terminal
Enter global configuration mode.
Step 2
ip arp inspection validate
{[
src-mac
] [
dst-mac
] [
ip
]}
Perform a specific check on incoming ARP packets. By default, no checks
are performed.
The keywords have these meanings:
•
For
src-mac
, check the source MAC address in the Ethernet header
against the sender MAC address in the ARP body. This check is
performed on both ARP requests and responses. When enabled, packets
with different MAC addresses are classified as invalid and are dropped.
•
For
dst-mac
, check the destination MAC address in the Ethernet header
against the target MAC address in ARP body. This check is performed
for ARP responses. When enabled, packets with different MAC
addresses are classified as invalid and are dropped.
•
For
ip
, check the ARP body for invalid and unexpected IP addresses.
Addresses include 0.0.0.0, 255.255.255.255, and all IP multicast
addresses. Sender IP addresses are checked in all ARP requests and
responses, and target IP addresses are checked only in ARP responses.
You must specify at least one of the keywords. Each command overrides the
configuration of the previous command; that is, if a command enables
src
and
dst mac
validations, and a second command enables IP validation only,
the
src
and
dst mac
validations are disabled as a result of the second
command.
Step 3
exit
Return to privileged EXEC mode.
Step 4
show ip arp inspection vlan
vlan-range
Verify your settings.
Step 5
copy running-config startup-config
(Optional) Save your entries in the configuration file.
