F3726, F3211, F3174, R5135, R3816-HP Firewalls and UTM Devices Network Management Command Reference-6PW100

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Default command level
2: System level
Usage guidelines
With this feature enabled, the DHCP relay agent can dynamically record clients' IP-to-MAC bindings
after clients get IP addresses through DHCP. It also supports static bindings. You can manually configure
IP-to-MAC bindings on the DHCP relay agent, so that users can access external networks using fixed IP
addresses.
Upon receiving an ARP packet, the DHCP relay agent matches the sender's IP and MAC addresses in the
packet against the bindings (both dynamic and static). If no match is found, the DHCP relay agent does
not learn the ARP entry. The sending host cannot access external networks through the DHCP relay
agent.
The dhcp relay address-check enable command only checks IP and MAC addresses of clients.
Examples
# Enable address check on the DHCP relay agent.
<Sysname> system-view
[Sysname] interface gigabitethernet 0/1
[Sysname-GigabitEthernet0/1] dhcp relay address-check enable
dhcp relay check mac-address
Use dhcp relay check mac-address to enable MAC address check on the DHCP relay agent.
Use undo dhcp relay check mac-address to disable MAC address check on the DHCP relay agent.
Syntax
dhcp relay check mac-address
undo dhcp relay check mac-address
Default
This function is disabled.
Views
Interface view
Default command level
2: System level
Usage guidelines
With this function enabled, the DHCP relay agent compares the chaddr field of a received DHCP request
with the source MAC address field of the frame. If they are the same, the DHCP relay agent decides this
request as valid and forwards it to the DHCP server; if not, the DHCP request is discarded.
DHCP relay agents change the source MAC addresses when forwarding DHCP packets. Therefore, you
can enable MAC address check only on a DHCP relay agent directly connected to the DHCP clients.
Otherwise, valid DHCP packets may be discarded and clients cannot obtain IP addresses.
Examples
# Enable MAC address check on the DHCP relay agent.
<Sysname> system-view
[Sysname] interface gigabitethernet 0/1