If your Internet provider assigns you an additional public IP address range it usually is a separate IP range which is not adjacent to the existing address range. The existing Internet remote site can be used for the additional IP address range. However the IP addresses have to be entered in the router configuration and the handling of ARP requests has to be modified.

This article describes the necessary configuration changes so a separate IP address range can be used.


  • LCOS as of version 9.24 (download latest version)
  • SSH client for accessing the CLI (e.g. PuTTY)
  • Any web browser for accessing WEBconfig (optional)
  • Configured and functional Internet connection (Plain Ethernet) with several discontiguous IP address ranges


1) Configuring the IP addresses of the separate IP address range in the router:

The IP addresses can be configured in the following menu items:

2) Allow ARP requests from any network:

The upstream provider router will send ARP requests from the separate IP address range with a corresponding source address. As this network isn't known to the router (no remote site with matching IP address range), the ARP packets will be discarded. In order for the router to accept ARP requests from a separate IP address range the handling of ARP requests from non local networks has to be modified (Non-Loc.-ARP-Replies).

Connect to the CLI of the router via SSH and enter the following command:

set Setup/TCP-IP/Non-Loc.-ARP-Replies yes

As an alternative you can also change this setting in WEBconfig in the menu (Extras →) LCOS Menu Tree → Setup → TCP-IP → Non-Loc.-ARP-Replies.