How to Configure DHCP Option 121 - Classless Static Route Option

  • 7014944
  • 21-Apr-2014
  • 18-Apr-2016


Novell Open Enterprise Server 2 (OES 2) Linux
Novell Open Enterprise Server 11 (OES 11) Linux


How to configure DHCP Option 121 using the DNSDHCP management console.


- Launch the DNSDHCP management console
- Select the DHCP (OES Linux) tab
- Select the DHCP Service that you want to add DHCP Option 121 to
- Click on the button on the button bar that looks like a globe
- Click the Add button
- Select Option number "121" in the "DHCP Option Code" drop down list
- Select "List of (1 byte) Unsigned Integers" in the "Data Syntax" drop down list.
- Give the option a description, like: "Option121" or "Option-121", etc. (No spaces allowed) and click OK then OK

The option has now been added to the list of available options.
It must be configured on the service in order for it to be utilized.

- Select the same DHCP Service on which you want to configure the newly added DHCP Option
- Select the "Configured Options" tab
- Click Modify
- Select the new option in the "DHCP Available Options" list
- Click "Add >>" to move it to the "Selected DHCP Options" list
- Select "Option121" (or whatever you named it) in the "Selected DHCP Options" list

Configuration Example:
- If you are adding the subnet, with the router, to this new option, the first integer in the list would be the subnet mask. I.E. 24
- Click the add button to add an integer to your "List of (1 byte) Unsigned Integers" and type 24 and click the OK button
- Click the add button again to add another integer to your "List of (1 byte) Unsigned Integers". In this case it would be 10
- Followed by 27
- Followed by 129
- Now we need to keep following this process to add the router's IP address
- Click the add button again to add another integer to your "List of (1 byte) Unsigned Integers". In this case it would be 10

If you have the latest management console you will not get an error and can continue to add the values for the router's IP address, one at a time.

If you get the following error, it was fixed in the May 2015 updates so the rest of the document about this error and how to work around it won't be needed if you update to the latest management console.

- At this point you may get an error regarding a duplicate value.
  To work around this issue without updating the management console, just pick another number that isn't in the list already and click OK.  You will change it to what you want later.
27 Same as above
129 Same as above
Click the OK button

Now to fix the duplicate entries that we had to use place holders for.
- Open iManager
- Click on the Roles and Tasks button
- Click on Directory Administration
- Select Modify Object
- Browse your tree and find the DHCP Service object that you added this option to and click OK
- Select on the General tab
- Select the "dhcpOption" item in the "Valued Attributes" list
- Click Edit
- Select the item that contains the router's IP address information added earlier
- Click the button with a pencil on it to modify the octets of the router's IP address.
- Correctthe routers IP address and click OK
- Click OK
- Click Apply
- Click OK.
- Refresh the information displayed in the Management console and these changes will now show up.

DHCP Option 121 is now added and configured on the DHCP service object.
Restart the DHCP server to have DHCP begin handing it out this option to the devices that request it.

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