How does WAN link manager failover rules work?

Question

Under the WAN link manager Failover Rules, you can choose "AND" or "OR". If you have 3 rules, how does AND OR work? 
 
 Example 1: 
 Not able to ping 1.1.1.1 OR 
 Not able to ping 2.2.2.2 OR 
 Not able to ping 3.3.3.3 
 
 Example 2: 
 Not able to ping 1.1.1.1 AND 
 Not able to ping 2.2.2.2 AND 
 Not able to ping 3.3.3.3 
 
 What happens in each example if 1.1.1.1 is unreachable by the XG? Will the gateway be considered down or will all 3 IP addresses need to be unreachable before the gateway is considered down? 
 I have been told for example 1 all 3 IP addresses need to be unreachable for the gateway to be down. But that doesn't sound right. Can anybody confirm?

LuCar Toni · Answer

Depends on the configuration. 
 AND / OR are Logical conjunction. 
 
 https://en.wikipedia.org/wiki/Logical_conjunction 
 
 Example 1: 
 Not able to ping 1.1.1.1 OR 
 Not able to ping 2.2.2.2 OR 
 Not able to ping 3.3.3.3 
 
 If one host is not reachable, the Gateway is down. 
 
 Example 2: 
 Not able to ping 1.1.1.1 AND 
 Not able to ping 2.2.2.2 AND 
 Not able to ping 3.3.3.3 
 
 If all hosts are not reachable, the gateway is down.

LuCar Toni · Answer

actually it is super easy to reproduce this. 
 
 And there are some changes in the behavior. 
 
 Basically the OR means, the XG will only try the first gateway. 
 If the first fails, it will try the next one, if this one fails, it will try the next one. 
 
 Example one:

XG will only try to ping 8.8.8.8 - it will leave 8.8.4.4 and 1.2.3.4. 
 (1.2.3.4 is offline / not reachable). 
 Gateway is consider as UP.

Changing all operators to AND: 
 
 Gateway is down, because XG is trying to reach all Gateways at the same time.

Thats for a "custom gateway". 
 
 Now lets take a look at the predefined gateway.

Gateway is considered as "UP". 
 
 XG will only ping the first gateway.

OR: 
 
 Gateway consider as "DOWN". 
 
 Because XG cannot Reach 1.2.3.4.