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Chapter 20
Configuring Dynamic ARP Inspection
•
Configuring Dynamic ARP Inspection in DHCP Environments
This procedure shows how to configure dynamic ARP inspection when two switches support this feature.
Host 1 is connected to Switch A, and Host 2 is connected to Switch B as shown in
page
A DHCP server is connected to Switch A. Both hosts acquire their IP addresses from the same DHCP
server. Therefore, Switch A has the bindings for Host 1 and Host 2, and Switch B has the binding for
Host 2.
Dynamic ARP inspection depends on the entries in the DHCP snooping binding database to verify
Note
IP-to-MAC address bindings in incoming ARP requests and ARP responses. Make sure to enable DHCP
snooping to permit ARP packets that have dynamically assigned IP addresses. For configuration
information, see
For information on how to configure dynamic ARP inspection when only one switch supports the
feature, see the
Beginning in privileged EXEC mode, follow these steps to configure dynamic ARP inspection. You must
perform this procedure on both switches. This procedure is required.
Command
Step 1
show cdp neighbors
Step 2
configure terminal
Step 3
ip arp inspection vlan vlan-range
Step 4
interface interface-id
OL-23389-01
When you enable dynamic ARP inspection on the switch, policers that were configured to police
ARP traffic are no longer effective. The result is that all ARP traffic is sent to the CPU.
20-3. Both switches are running dynamic ARP inspection on VLAN 1 where the hosts are located.
Chapter 19, "Configuring DHCP Features and IP Source Guard Features."
"Configuring ARP ACLs for Non-DHCP Environments" section on page
Purpose
Verify the connection between the switches.
Enter global configuration mode.
Enable dynamic ARP inspection on a per-VLAN basis. By
default, dynamic ARP inspection is disabled on all VLANs.
For vlan-range, 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.
Specify the same VLAN ID for both switches.
Specify the interface connected to the other switch, and enter
interface configuration mode.
Catalyst 2928 Switch Software Configuration Guide
Configuring Dynamic ARP Inspection
Figure 20-2 on
20-8.
20-7
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Troubleshooting
