The following checklist is to configure LLT over UDP:
Make sure that the LLT private links are on different physical networks.
If the LLT private links are not on different physical networks, then make sure that the links are on separate subnets. Set the broadcast address in /etc/llttab explicitly depending on the subnet for each link.
Make sure that each NIC has an IP address that is configured before configuring LLT.
Make sure the IP addresses in the /etc/llttab files are consistent with the IP addresses of the network interfaces.
Make sure that each link has a unique not well-known UDP port.
Set the broadcast address correctly for direct-attached (non-routed) links.
For the links that cross an IP router, disable broadcast features and specify the IP address of each link manually in the /etc/llttab file.