38-8
Cisco 7600 Series Router Cisco IOS Software Configuration Guide, Release 12.2SX
OL-4266-08
Chapter 38 Configuring Dynamic ARP Inspection
Configuring DAI
Vlan ACL Logging DHCP Logging
---- ----------- ------------
10 Deny Deny
11 Deny Deny
12 Deny Deny
15 Deny Deny
Configuring the DAI Interface Trust State
The router forwards ARP packets that it receives on a trusted interface, but does not check them.
On untrusted interfaces, the router 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 router 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 DAI Logging” section on
page 38-13
.
To configure the DAI interface trust state, perform this task:
This example shows how to configure Fast Ethernet port 5/12 as trusted:
Router#
configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#
interface fastethernet 5/12
Router(config-if)#
ip arp inspection trust
Router(config-if)#
do show ip arp inspection interfaces | include Int|--|5/12
Interface Trust State Rate (pps) Burst Interval
--------------- ----------- ---------- --------------
Fa5/12 Trusted None N/A
Applying ARP ACLs for DAI Filtering
Note
See the
Cisco IOS Master Command List
, Release 12.2SX, for information about the
arp access-list
command.
Command
Purpose
Step 1
Router#
configure terminal
Enters global configuration mode.
Step 2
Router(config)#
interface
{
type
1
slot/port
|
port-channel
number
}
1.
type
=
ethernet
,
fastethernet
,
gigabitethernet
, or
tengigabitethernet
Specifies the interface connected to another router, and
enter interface configuration mode.
Step 3
Router(config-if)#
ip arp inspection trust
Configures the connection between routers as trusted
(default: untrusted).
Router(config)#
no ip arp inspection trust
Configures the connection between routers as untrusted.
Step 4
Router(config-if)#
do show ip arp inspection
interfaces
Verifies the DAI configuration.