Related Documentation
Enabling and Disabling DHCP Snooped Packets Support for DHCP Relay Agent
DHCP relay agent uses a two-part configuration to determine how to handle DHCP snooped packets. This topic describes the first procedure, in which you configure DHCP relay to either enable or disable support for snooped packets.
The second procedure, which applies only to DHCPv4 relay agent, is described in Configuring DHCP Snooped Packets Forwarding Support for DHCP Relay Agent, and configures the forward-snooped-clients statement, which determines whether the snooped packets are forwarded or dropped, depending on the type of interface.
 | Note: The router (or switch) has a default global setting that specifies whether DHCP snooping support is enabled or disabled for DHCP relay. In Junos OS Release 10.0 and earlier, DHCP snooping is enabled by default. In Junos OS Release 10.1 and later and in Junos OS 12.3R2 and later for EX Series switches, DHCP snooping is disabled by default. |
You can override the default global DHCP snooping configuration and explicitly enable or disable DHCP snooping support. You can configure the explicit snooping support globally, for a group of interfaces, or for a specific interface in a group.
- To enable DHCP relay or DHCPv6 relay snooping support, include the allow-snooped-clients option in the overrides statement.
- To disable DHCP relay or DHCPv6 relay snooping support, include the no-allow-snooped-clients option in the overrides statement.
To enable or disable DHCP snooping support globally:
- Specify that you want to configure DHCP relay agent.
- For DHCP relay agent:[edit]user@host# edit forwarding-options dhcp-relay
- For DHCPv6 relay agent:[edit]user@host# edit forwarding-options dhcp-relay dhcpv6
- For DHCP relay agent:
- Specify that you want to override the default configuration.
- Enable or disable DHCP snooping support.
- To enable DHCP snooping:
- For DHCP relay agent:[edit forwarding-options dhcp-relay overrides]user@host# set allow-snooped-clients
- For DHCPv6 relay agent:[edit forwarding-options dhcp-relay dhcpv6 overrides]user@host# set allow-snooped-clients
- For DHCP relay agent:
- To disable DHCP snooping:
- For DHCP relay agent:[edit forwarding-options dhcp-relay overrides]user@host# set no-allow-snooped-clients
- For DHCPv6 relay agent:[edit forwarding-options dhcp-relay dhcpv6 overrides]user@host# set no-allow-snooped-clients
- For DHCP relay agent:
- To enable DHCP snooping:
For example, to enable global DHCP snooping support :
To enable or disable DHCP snooping support for a group of interfaces:
- Specify that you want to configure DHCP relay agent.
- For DHCP relay agent:[edit]user@host# edit forwarding-options dhcp-relay
- For DHCPv6 relay agent:[edit]user@host# edit forwarding-options dhcp-relay dhcpv6
- For DHCP relay agent:
- Specify the named group.
- Specify that you want to override the default configuration.
- Enable or disable DHCP snooping support.
- To enable DHCP snooping:
- For DHCP relay agent:[edit forwarding-options dhcp-relay group group-name overrides]user@host# set allow-snooped-clients
- For DHCPv6 relay agent:[edit forwarding-options dhcp-relay dhcpv6 group group-name overrides]user@host# set allow-snooped-clients
- For DHCP relay agent:
- To disable DHCP snooping:
- For DHCP relay agent:[edit forwarding-options dhcp-relay group group-name overrides]user@host# set no-allow-snooped-clients
- For DHCPv6 relay agent:[edit forwarding-options dhcp-relay dhcpv6 group group-name overrides]user@host# set no-allow-snooped-clients
- For DHCP relay agent:
- To enable DHCP snooping:
For example, to enable DHCP snooping support on all interfaces in group boston:
To enable or disable DHCP snooping support on a specific interface:
- Specify that you want to configure DHCP relay agent.
- For DHCP relay agent:[edit]user@host# edit forwarding-options dhcp-relay
- For DHCPv6 relay agent:[edit]user@host# edit forwarding-options dhcp-relay dhcpv6
- For DHCP relay agent:
- Specify the named group containing the interface.
- Specify the interface for which you want to configure DHCP snooping.
- Specify that you want to override the default configuration on the interface.
- Enable or disable DHCP snooping support.
- To enable DHCP snooping:
- For DHCP relay agent:[edit forwarding-options dhcp-relay group group-name interface interface-name overrides]user@host# set allow-snooped-clients
- For DHCPv6 relay agent:[edit forwarding-options dhcp-relay dhcpv6 group group-name interface interface-name overrides]user@host# set allow-snooped-clients
- For DHCP relay agent:
- To disable DHCP snooping:
- For DHCP relay agent:[edit forwarding-options dhcp-relay group group-name interface interface-name overrides]user@host# set no-allow-snooped-clients
- For DHCPv6 relay agent:[edit forwarding-options dhcp-relay dhcpv6 group group-name interface interface-name overrides]user@host# set no-allow-snooped-clients
- For DHCP relay agent:
- To enable DHCP snooping:
For example, to disable DHCP snooping support on interface ge-2/1/8.0 in group boston:
To enable DHCPv6 snooping support on interface ge-3/2/1.1 in group sunnyvale:
