Administrator Guide
Conguring Dynamic ARP Inspection
To enable dynamic ARP inspection, use the following commands.
1 Enable DHCP snooping.
2 Validate ARP frames against the DHCP snooping binding table.
INTERFACE VLAN mode
arp inspection
Examples of Viewing the ARP Information
To view entries in the ARP database, use the show arp inspection database command.
Dell#show arp inspection database
Protocol Address Age(min) Hardware Address Interface VLAN CPU
---------------------------------------------------------------------
Internet 10.1.1.251 - 00:00:4d:57:f2:50 Gi 1/2 Vl 10 CP
Internet 10.1.1.252 - 00:00:4d:57:e6:f6 Gi 1/1 Vl 10 CP
Internet 10.1.1.253 - 00:00:4d:57:f8:e8 Gi 1/3 Vl 10 CP
Internet 10.1.1.254 - 00:00:4d:69:e8:f2 Gi 1/5 Vl 10 CP
Dell#
To see how many valid and invalid ARP packets have been processed, use the show arp inspection statistics command.
Dell#show arp inspection statistics
Dynamic ARP Inspection (DAI) Statistics
---------------------------------------
Valid ARP Requests : 0
Valid ARP Replies : 1000
Invalid ARP Requests : 1000
Invalid ARP Replies : 0
Dell#
Bypassing the ARP Inspection
You can congure a port to skip ARP inspection by dening the interface as trusted, which is useful in multi-switch environments.
ARPs received on trusted ports bypass validation against the binding table. All ports are untrusted by default.
To bypass the ARP inspection, use the following command.
• Specify an interface as trusted so that ARPs are not validated against the binding table.
INTERFACE mode
arp inspection-trust
Dynamic ARP inspection is supported on Layer 2 and Layer 3.
262
Dynamic Host Conguration Protocol (DHCP)