448 ConfiguringSwitching Information
•
Bad Source MAC
— The number of ARP packets that were dropped by DAI because the sender MAC
address in the ARP packet did not match the source MAC in the Ethernet header.
•
Bad Dest MAC
— The number of ARP packets that were dropped by DAI because the target MAC
address in the ARP reply packet did not match the destination MAC in the Ethernet header.
•
Invalid IP
— The number of ARP packets dropped by DAI because the sender IP address in the ARP
packet or target IP address in the ARP reply packet is not valid. Invalid addresses include 0.0.0.0,
255.255.255.255, IP multicast addresses, class E addresses (240.0.0.0/4), and loopback addresses
(127.0.0.0/8).
•
Forwarde d
— The number of valid ARP packets forwarded by DAI.
•
Dropped
— The number of not valid ARP packets dropped by DAI.
Viewing Dynamic ARP Inspection Statistics With CLI Commands
For information about the CLI commands that per form this function, refer to the following chapter in
the
CLI Reference Guide
:
• Dynamic ARP Inspection Commands
The following table summarizes the equivalent CLI commands for this feature.
DHCP Snooping
DHCP snooping is a security feature that monitors DHCP messages between a DHCP client and DHCP
servers to filter harmful DHCP messages and to build a bindings database of MAC address, IP address,
VLAN ID, and port tuples that are considered authorized. You can enable DHCP snooping globally, per-
interface, and on specific VLANs, and configure ports within the VLAN to be trusted or untrusted.
DHCP servers must be reached through trusted ports.
DHCP snooping enforces the following security rules:
• DHCP packets from a DHCP server (DHCPOFFER, DHCPACK, DHCPNAK,
DHCPRELEASEQUERY) are dropped if received on an untrusted port.
• DHCPRELEASE and DHCPDECLINE messages are dropped if for a MAC address in the snooping
database, but the binding’s interface is other than the interface where the message was received.
• On untrusted interfaces, the switch drops DHCP packets whose source MAC address does not match
the client hardware address. This feature is a configurable option.
Table 7-63. Dynamic ARP Inspection Command
CLI Command Description
show ip arp inspection statistics Displays the statistics of the ARP packets processed by Dynamic ARP
Inspection.
clear counters ip arp inspection Resets the statistics for Dynamic ARP Inspection on all VLANs.