Related Documentation
Disabling Automatic Binding of Stray DHCP Requests
DHCP requests that are received but have no entry in the database are known as stray requests. By default, DHCP relay, DHCP relay proxy, and DHCPv6 relay agent attempt to bind the requesting client by creating a database entry and forwarding the request to the DHCP server. If the server responds with an ACK, the client is bound and the ACK is forwarded to the client. If the server responds with a NAK, the database entry is deleted and the NAK is forwarded to the client. This behavior occurs regardless of whether authentication is configured.
You can override the default configuration at the global level, for a named group of interfaces, or for a specific interface within a named group. Overriding the default causes DHCP relay, DHCP relay proxy, and DHCPv6 relay agent to drop all stray requests instead of attempting to bind the clients.
 | Note: In Junos OS Release 10.4 and later, automatic binding of stray requests is enabled by default. In Junos OS Release 10.3 and earlier releases, automatic binding of stray requests is disabled by default. In those releases, DHCP relay drops stray requests and forwards a NAK to the client when authentication is configured. Otherwise, DHCP relay attempts to bind the requesting client. In those releases, DHCP relay proxy always drops stray requests and forwards a NAK to the client, regardless of the authentication configuration. |
- To disable automatic binding behavior, include the no-bind-on-request statement when you configure DHCP overrides
at the global, group, or interface level.[edit forwarding-options dhcp-relay overrides]user@host# set no-bind-on-request
- To override the default behavior for DHCPv6 relay agent,
configure the override at the [edit forwarding-options dhcp-relay dhcpv6] hierarchy level. [edit forwarding-options dhcp-relay dhcpv6 overrides]user@host# set no-bind-on-request
The following two examples show a configuration that disables automatic binding of stray requests for a group of interfaces and a configuration that disables automatic binding on a specific interface.
To disable automatic binding of stray requests on a group of interfaces:
- Specify the named group.[edit forwarding-options dhcp-relay]user@host# edit group boston
- Specify that you want to configure overrides.[edit forwarding-options dhcp-relay group boston]user@host# edit overrides
- Disable automatic binding for the group.[edit forwarding-options dhcp-relay group boston overrides]user@host# set no-bind-on-request
To disable automatic binding of stray requests on a specific interface:
- Specify the named group of which the interface is a member. [edit forwarding-options dhcp-relay]user@host# edit group boston
- Specify the interface on which you want to disable automatic
binding. [edit forwarding-options dhcp-relay group boston]user@host# edit interface fe-1/0/1.2
- Specify that you want to configure overrides.[edit forwarding-options dhcp-relay group boston interface fe-1/0/1.2]user@host# edit overrides
- Disable automatic binding on the interface.[edit forwarding-options dhcp-relay group boston interface fe-1/0/1.2 overrides]user@host# set no-bind-on-request
