How to send logs from devices that don't have access to internet

[I29851]

I trying to implement Splunk across multiple domains. Due to company policy some domains don't have access to internet and as a result servers in those domain cannot communicate with indexers located in Splunk cloud. 

What is the best way to send data to indexer in this case? One of the suggestions we received is to use heavy forwarder as intermediate. But it will introduce single point of failure so we might need to implement load balancer.

Is their any other way possible?

[richgalloway]

The recommended way to resolve this problem is to use multiple heavy forwarders.  Using 3 instead of 2 to prevent SPOF because if one fails then 2 are better able to keep up with the load.

A load balancer in front of the HFs is also recommended, but not necessary.  Just configure the UFs in each domain to send to all HFs (in outputs.conf) and the UFs will automatically load balance to the HFs.