SD-RED, how to setup primary and backup sites

Question

Dear Experts, 
 Can someone highlight if below scenario is possible with XG and SD-RED 
 
 1) 1 Primary site with 2 Internet links 
 2) 1 DR site with 2 internet links 
 3 ) 1 Branch site with 2 (or 1 ) internet links 
 Physical connections on RED will be 2 as mentioned above. But can i configure it in such a way that RED can connect to DR site if either the primary site goes down (XG is down) or if the links to XG are down?

KingChris · Answer

Hi adnan khan 
 You can do this provided that the XG in primary site and XG in DR site are in HA. 
 This means that you would need a high speed link with a round trip between the 2 sites not exceeding 7 seconds. 
 The branch site would connect to the primary site XG (which is in HA with DR site) via a RED device or another XG setup for RED tunneling. 
 In your HA configuration you would then set it to monitor both internet interfaces and internal interfaces. 
 Thanks!