Configure a DHCP server

Note These instructions assume you are configuring the device to use its local DHCP server. For instructions about configuring the device to use a DHCP relay server, see Configure DHCP relay.

Required configuration items

Additional configuration items

 

  1. Log into Digi Remote Manager, or log into the local Web UI as a user with full Admin access rights.
  2. Access the device configuration:

    1. Locate your device as described in Use Digi Remote Manager to view and manage your device.
    2. Click the Device ID.
    3. Click Settings.
    4. Click to expand Config.

    1. On the menu, click System. Under Configuration, click Device Configuration.

      The Configuration window is displayed.

  3. Click Network > Interfaces.
  4. Click to expand an existing LAN, or create a new LAN. See Configure a Local Area Network (LAN).
  5. Click to expand IPv4 > DHCP server.
  6. Enable the DHCP server.
  7. (Optional) For Lease time, type the amount of time that a DHCP lease is valid.

    Allowed values are any number of weeks, days, hours, minutes, or seconds, and take the format number{w|d|h|m|s}.

    For example, to set Lease time to ten minutes, enter 10m or 600s.

    The default is 12 hours.

  8. (Optional) For Lease range start and Lease range end, type the lowest and highest IP address that the DHCP server will assign to a client. This value represents the low order byte of the address (the final triplet in an IPv4 address, for example, 192.168.2.xxx). The remainder of the IP address will be based on the LAN's static IP address as defined in the Address field.

    Allowed values are between 1 and 254, and the default is 100 for Lease range start and 250 for Lease range end.

    • By default, DHCP addresses are assigned psuedo-randomly, using a hash of the client's MAC address to determine the IP address that gets assigned. You can configure the device to use sequential IP addresses instead:

      1. Click Network > Advanced.

      2. Click to enable Sequential DHCP address allocation.

      Because sequential mode does not use a hash based on the client's MAC address, when DHCP lease expires, the client is not likely to get the same IP address assigned to it. Therefore, sentential DHCP address allocation generally should not be used.

    1. Click to expand Advanced settings.
    2. For Gateway, select either:
      • None: No gateway is broadcast by the DHCP server. Client destinations must be resolvable without a gateway.
      • Automatic: Broadcasts the EX12 device's gateway.
      • Custom: Allows you to identify the IP address of a Custom gateway to be broadcast.

      The default is Automatic.

    3. For MTU,
      • None: An MTU of length 0 is broadcast. This is not recommended.
      • Automatic: No MTU is broadcast and clients will determine their own MTU.
      • Custom: Allows you to identify a Custom MTU to be broadcast.

      The default is Automatic.

    4. For Domain name suffix, type the domain name that should be appended to host names.
    5. For Primary and Secondary DNS, Primary and Secondary NTP server, and Primary and Secondary WINS server, select either:
      • None: No server is broadcast.
      • Automatic: Broadcasts the EX12 device's server.
      • Custom: Allows you to identify the IP address of the server.
    6. Enable BOOTP dynamic allocation to automatically assign an IP address to a device on the server.

      7. CAUTION! The IP address assigned to the device is leased forever and becomes permanently unavailable for other hosts to use.

    7. For Bootfile name, type the relative path and file name of the bootfile on the TFTP server.
    8. For TFTP server name, type the IP address or host name of the TFTP server.
    9. Enable
  10. See Configure DHCP options for information about Custom DHCP options.
  11. See Map static IP addresses to hosts for information about Static leases.
  12. Click Apply to save the configuration and apply the change.
  1. Select the device in Remote Manager and click Actions > Open Console, or log into the EX12 local command line as a user with full Admin access rights.

    Depending on your device configuration, you may be presented with an Access selection menu. Type admin to access the Admin CLI.

  2. At the command line, type config to enter configuration mode:

    > config
(config)>

  3. Enable the DHCP server for an existing LAN. For example, to enable the DHCP server for a LAN named my_lan:
    (config)> network interface my_lan ipv4 dhcp_server enable true
(config)>

    See Configure a Local Area Network (LAN) for information about creating a LAN.

  4. (Optional) Set the amount of time that a DHCP lease is valid:
    (config)> network interface my_lan ipv4 dhcp_server lease_time value
(config)>

    where value is any number of weeks, days, hours, minutes, or seconds, and takes the format number{w|d|h|m|s}.

    For example, to set network interface my_lan ipv4 dhcp_server lease_time to ten minutes, enter either 10m or 600s:

    (config)> network interface my_lan ipv4 dhcp_server lease_time 600s
(config)>

    • By default, DHCP leases are persistent across reboots. You can disable persistent leases:

      (config)> network advanced dhcp_persistent_lease false
(config)>
  5. (Optional) Set the lowest IP address that the DHCP server will assign to a client. This value represents the low order byte of the address (the final triplet in an IPv4 address, for example, 192.168.2.xxx). The remainder of the IP address will be based on the LAN's static IP address as defined in the address parameter.
    (config)> network interface my_lan ipv4 dhcp_server lease_start num
(config)>

    Allowed values are between 1 and 254, and the default is 100.

  6. (Optional) Set the highest IP address that the DHCP server will assign to a client:
    (config)> network interface my_lan ipv4 dhcp_server lease_end num
(config)>

    Allowed values are between 1 and 254, and the default is 250.

  7. By default, DHCP addresses are assigned psuedo-randomly, using a hash of the client's MAC address to determine the IP address that gets assigned. You can configure the device to use sequential IP addresses instead:

    (config)> network advanced sequential_dhcp_allocation true
(config)>

    Because sequential mode does not use a hash based on the client's MAC address, when DHCP lease expires, the client is not likely to get the same IP address assigned to it. Therefore, sentential DHCP address allocation generally should not be used.

    1. Click to expand Advanced settings.
    2. Determine how the DHCP server should broadcast the gateway server:
      (config)> network interface my_lan ipv4 dhcp_server advanced gateway value
(config)>

      where value is one of:

      • none: No gateway is broadcast by the DHCP server. Client destinations must be resolvable without a gateway.
      • auto: Broadcasts the EX12 device's gateway.
      • custom: Allows you to identify the IP address of a custom gateway to be broadcast:
        (config)> network interface my_lan ipv4 dhcp_server advanced gateway_custom ip_address
(config)>

      The default is auto.

    3. Determine how the DHCP server should broadcast the the MTU:
      (config)> network interface my_lan ipv4 dhcp_server advanced mtu value
(config)>

      where value is one of:

      • none: An MTU of length 0 is broadcast. This is not recommended.
      • auto: No MTU is broadcast and clients will determine their own MTU.
      • custom: Allows you to identify a custom MTU to be broadcast:
        (config)> network interface my_lan ipv4 dhcp_server advanced mtu_custom mtu
(config)>

      The default is auto.

    4. Set the domain name that should be appended to host names:
      (config)> network interface my_lan ipv4 dhcp_server advanced domain_suffix name
(config)>
    5. Set the IP address or host name of the primary and secondary DNS, the primary and secondary NTP server, and the primary and secondary WINS servers:
      (config)> network interface my_lan ipv4 dhcp_server advanced primary_dns value
(config)> network interface my_lan ipv4 dhcp_server advanced secondary_dns value
(config)> network interface my_lan ipv4 dhcp_server advanced primary_ntp value
(config)> network interface my_lan ipv4 dhcp_server advanced secondary_ntp value
(config)> network interface my_lan ipv4 dhcp_server advanced primary_wins value
(config)> network interface my_lan ipv4 dhcp_server advanced secondary_wins value
(config)>

      where value is one of:

      • none: No server is broadcast.
      • auto: Broadcasts the EX12 device's server.
      • custom: Allows you to identify the IP address of the server. For example:
        (config)> network interface my_lan ipv4 dhcp_server advanced primary_dns_custom ip_address
(config)>

      The default is auto.

    6. Set the IP address or host name of the TFTP server:
      (config)> network interface my_lan ipv4 dhcp_server advanced nftp_server ip_address
(config)>
    7. Set the relative path and file name of the bootfile on the TFTP server:
      (config)> network interface my_lan ipv4 dhcp_server advanced bootfile filename
(config)>
    8. Enable BOOTP dynamic allocation to automatically assign an IP address to a device on the server:

      9. CAUTION! The IP address assigned to the device is leased forever and becomes permanently unavailable for other hosts to use.

      (config)> network interface my_lan ipv4 dhcp_server advanced bootp_dynamic true
(config)>
  9. See Configure DHCP options for information about custom DHCP options.
  10. See Map static IP addresses to hosts for information about static leases.
  11. Save the configuration and apply the change.
    (config network interface my_lan ipv4 dhcp_server advanced static_lease 0)> save
Configuration saved.
>
  12. Type exit to exit the Admin CLI.

    Depending on your device configuration, you may be presented with an Access selection menu. Type quit to disconnect from the device.