Configuring DHCP Reservation (Fixed IP Assignments)

DHCP (Dynamic Host Control Protocol) Reservation configuration is located at Networking > General > DHCP Reservation (Fixed IP Assignments).

Normally when a client device connects to the router’s LAN, DHCP assigns an available IP address from its LAN segment address pool (Networking > Zones settings > LAN Segments) — the IP address may vary from connection to connection.

However, DHCP reservation can be used to create fixed IP assignments (reserved IP addresses) for specific clients. With a fixed IP assignment, the client always receives the same IP address when it connects to the LAN. (Note — A DHCP reservation is similar to a static IP address, except DHCP handles the addressing and the client does not need to be configured with a static IP.)

The DHCP Reservation section includes two tables — an ADDRESS BINDING TABLE showing all connected devices, and a FIXED IP ASSIGNMENT table showing all fixed IP assignments that have been been created.

When a client device connects to the router, one or two entries automatically appear in the ADDRESS BINDING TABLE (one entry for each IP address type (IPv4 or IPv6) supported by the client). For each entry, DHCP either assigns a dynamic address or uses a FIXED IP ASSIGNMENT address if one has already been created.

For example, the ADDRESS BINDING TABLE above shows two connected devices (CARMEL-002781 and mX230), and two defined FIXED IP ASSIGNMENTs (one for CARMEL-002781’s IPv4 connection, and one for IPixel, which is not currently connected).

DHCP automatically applied the defined fixed IP assignment to CARMEL-002781’s IPv4 connection, and dynamic addresses to CARMEL-002781’s IPv6 connection and mX230’s IPv4 connection.

Fixed IP assignments can be added for any connected devices in the ADDRESS BINDING TABLE, or created in advance for devices that are not yet connected.

Configuring Fixed IP Assignments

To add a fixed IP assignment for a connected device:

1. Click ADD at the end of the device row in the ADDRESS BINDING TABLE.
   
   An entry is saved to the FIXED IP ASSIGNMENT table using the ADDRESS BINDING TABLE details, and the ADDRESS BINDING TABLE entry locks the ADD button to show an assignment now exists ( ).

To either create an assignment in advance for a device or edit an existing assignment:

1. Click CREATE FIXED IP ASSIGNMENT, or click Edit at the end of a row in the FIXED IP ASSIGNMENT table.
   
   The Create Fixed IP Assignment or Edit Fixed IP Assignment menu appears.

2. Configure the fields in any order:

   • Select the HOST IDENTIFIER TYPE used to identify the client device:
     • MAC Address — The physical address of the device’s network interface card.
     • Client ID (or DUID) — The client device’s unique DHCP Client Identifier (for IPv4) or DHCPv6 Unique Identifier (for IPv6).
   • (Required) Enter the HOST IDENTIFIER VALUE for the selected Host Identifier Type — for MAC Address, enter the client device’s MAC address (e.g., 3e:bb:5a:e1:a9:c0), or for Client ID (or DUID), enter the DHCP Client ID the device provides.

   • Enter the IP address(es) the client will use when it connects (Note — If the client supports both address types, enter fixed addresses for each type):

     • Enter the fixed IPV4 ADDRESS.
     • Enter the fixed IPV6 ADDRESS.

   • Enter a HOSTNAME to easily identify the client device. This name appears in both the ADDRESS BINDING TABLE and the FIXED IP ASSIGNMENT table.

   • Enter the LEASE PERIOD (IN MINS) for the IP assignment — if this field is blank, the LAN segment’s Lease Time will be used.
     
     When the lease period expires, the client device either renews the lease and updates the ADDRESS BINDING TABLE entry with the current settings from the fixed IP assignment, or drops the connection.
     
     

3. Click CREATE or UPDATE to save the fixed IP assignment.

4. Click SAVE on the orange status bar ( ) to apply the new or updated fixed IP assignment.
   
   AirLink OS validates the assignment and updates the FIXED IP ASSIGNMENT table’s Status field with “Successfully Assigned” or an error message (e.g., “Invalid IPv4 address, please specify address based on the LAN segment’s prefix length”, etc.)
   
   

To delete a fixed IP assignment:

• Click Delete at the end of the row in the FIXED IP ASSIGNMENT table.
  After the change is saved, if the device is currently shown in the ADDRESS BINDING TABLE (i.e., currently connected), its ADD button is automatically unlocked.