46-7
Software Configuration Guide—Release 15.0(2)SG
OL-23818-01
Chapter 46 Configuring Dynamic ARP Inspection Configuring Dynamic ARP Inspection
DAI Configuration Example
This example shows how to configure DAI on Switch A in VLAN 100. You would perform a similar
procedure on Switch B.

Switch A

SwitchA# show cdp neighbors
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone
Device ID Local Intrfce Holdtme Capability Platform Port ID
SwitchB Gig 3/48 179 R S I WS-C4506 Gig 3/46
SwitchA# configure terminal
SwitchA(config)# ip arp inspection vlan 100
SwitchA(config)# interface g3/48
SwitchA(config-if)# ip arp inspection trust
SwitchA(config-if)# end
SwitchA# show ip arp inspection interfaces
Interface Trust State Rate (pps) Burst Interval
--------------- ----------- ---------- --------------
Gi1/1 Untrusted 15 1
Gi1/2 Untrusted 15 1
Step 5 Switch(config-if)# ip arp inspection trust Configures the connection between the switches as trusted.
To return the interfaces to an untrusted state, use the
no ip arp inspection trust interface configuration command.
By default, all interfaces are untrusted.
The switch does not check ARP packets that it receives from the
other switch on the trusted interface. It forwards the packets.
For untrusted interfaces, the switch intercepts all ARP requests
and responses. It verifies that the intercepted packets have valid
IP-to-MAC address bindings before updating the local cache and
before forwarding the packet to the appropriate destination. The
switch drops invalid packets and logs them in the log buffer
according to the logging configuration specified with the
ip arp inspection vlan logging global configuration command.
For more information, see the “Configuring the Log Buffer”
section on page 46-14.
Step 6 Switch(config-if)# end Returns to privileged EXEC mode.
Step 7 Switch# show ip arp inspection interfaces
Switch# show ip arp inspection vlan
vlan-range
Verifies the DAI configuration.
Step 8 Switch# show ip dhcp snooping binding Verifies the DHCP bindings.
Step 9 Switch# show ip arp inspection statistics
vlan vlan-range Checks the DAI statistics.
Step 10 Switch# copy running-config startup-config (Optional) Saves your entries in the configuration file.
Command Purpose