R0106-HP MSR Router Series Layer 3 - IP Services Command Reference(V7)

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DHCP relay agent commands
dhcp relay check mac-address
Use dhcp relay check mac-address to enable MAC address check on the relay agent.
Use undo dhcp relay check mac-address to disable MAC address check on the relay agent.
Syntax
dhcp relay check mac-address
undo dhcp relay check mac-address
Default
The MAC address check function is disabled.
Views
Interface view
Predefined user roles
network-admin
Usage guidelines
This function enables the DHCP relay agent to compare the chaddr field of a received DHCP request with
the source MAC address in the frame header. If they are the same, the DHCP relay agent forwards the
request to the DHCP server. If they are not the same, the DHCP relay agent discards the request.
The MAC address check function takes effect only when the dhcp select relay command has been
configured on the interface.
Enable the MAC address check function only on the DHCP relay agent directly connected to the DHCP
clients. A DHCP relay agent changes the source MAC address of DHCP packets before sending them. If
you enable this feature on an intermediate relay agent, it might discard valid DHCP packet, and the
sending clients will not obtain IP addresses.
Examples
# Enable MAC address check on the relay agent.
<Sysname> system-view
[Sysname] interface gigabitethernet 2/1/1
[Sysname-GigabitEthernet2/1/1] dhcp relay check mac-address
Related commands
dhcp select relay
dhcp relay check mac-address aging time
Use dhcp relay check mac-address aging time to configure the aging time for MAC address check
entries on the DHCP relay agent.
Use undo dhcp relay check mac-address aging time to restore the default.
Syntax
dhcp relay check mac-address aging-time time