Purpose
Command or Action
•
For
vlan-range
, specify the VLAN that the switches and hosts are in. You can
specify a single VLAN identified by VLAN ID number, a range of VLANs
separated by a hyphen, or a series of VLANs separated by a comma. The range
is 1 to 4094.
•
(Optional) Specify
static
to treat implicit denies in the ARP ACL as explicit
denies and to drop packets that do not match any previous clauses in the ACL.
DHCP bindings are not used.
If you do not specify this keyword, it means that there is no explicit deny in the
ACL that denies the packet, and DHCP bindings determine whether a packet is
permitted or denied if the packet does not match any clauses in the ACL.
ARP packets containing only IP-to-MAC address bindings are compared against the
ACL. Packets are permitted only if the access list permits them.
Specify the Switch A interface that is connected to Switch B, and enter interface
configuration mode.
interface interface-id
Step 6
Configure the Switch A interface that is connected to Switch B as untrusted.
no ip arp inspection trust
Step 7
By default, all interfaces are untrusted.
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 section,
“
Configuring the Log
Buffer."
Return to privileged EXEC mode.
end
Step 8
Verify your entries.
show arp access-list
acl-name
show ip arp inspection vlan
Step 9
vlan-range show ip arp
inspection interfaces
(Optional) Save your entries in the configuration file.
copy running-config
startup-config
Step 10
To remove the ARP ACL, use the
no arp access-list
global configuration command. To remove the ARP
ACL attached to a VLAN, use the
no ip arp inspection filter arp-acl-name vlan vlan-range
global
configuration command.
Catalyst 2960-XR Switch Security Configuration Guide, Cisco IOS Release 15.0(2)EX1
204
OL-29434-01
Configuring Dynamic ARP Inspection
Configuring ARP ACLs for Non-DHCP Environments