Q: What is the Platform and License Requirement for SDWAN High availability?
The Platform and licenses should be same for both devices which participates in HA
 
Q: What protocol and port numbers used by SDWAN for HA communication?
SDWAN uses Citrix Proprietary protocol for HA communication and UDP port 4980
 
Q: What is the default hello packet interval and Failover time?
Hello packets exchanged every 100ms and Failover is triggered after 1 second of silence period by default
 
Q: Which interface is used to send the Heartbeat packets?
All interfaces which is part of High Availability interface group is used for Heartbeat communication
 
Q: Can we add multiple interface as part of HA group?
Yes, we can add multiple interfaces as part of HA group
 
Q: Can we change the Hello Packet interval in configuration?
No, we cannot modify default Hello Packet interval
 
Q: Can we form a High Availability between 2 different subnet High Availability control IP's?
No, High Availability IP's should be on the same subnet as HA access interface subnet
 
Q: Can we do the PING test to check the communication between the appliances?
No, HA packets are initiated from the SDWAN software and PING test is not possible from CLI/SHELL
 
Q: What information is synchronized between SDWAN appliances?
Configuration and High Availability state is synchronized between the appliances
 
Q: Does VIP's uses individual or shared VMAC address for communication?
SDWAN VIP's uses shared MAC addresses to communication with other devices by default however this behaviour can be modified in the configuration
 
Q: What interfaces are monitored in SDWAN HA deployment?
All physical interfaces which is part of High Availability access interface group is monitored

Q: Does SDWAN monitor the interfaces by default for failure?.
No, By default SDWAN appliance doesn't monitor the interfaces unless the interface is part of HA group
 
Q: What are all the components monitored to declare the device working state?
All HA Interfaces are monitored to determine the device health
 
Q: How to trigger the Force failover?
Please refer the following Citrix article https://support.citrix.com/article/CTX213510
 
Q: What is the recommended procedure for upgrading SDWAN High Availability setup?
Please refer the following Citrix documentation https://docs.netscaler.com/en-us/citrix-sd-wan-platforms/cb-deployment-modes-con/br-adv-high-avail-mode-con/br-adv-updat-sw-high-avail-tsk.htm

Q. How to Configure a Citrix SDWAN in high Availability mode?.
Please refer the following Citrix article https://support.citrix.com/article/CTX227522
 
Q: How SDWAN Failover state is detected when the device boots up first time?
1. Configuration File Date (Newer is better)
2. HA priority (Primary or Secondary)
3. MAC address (only used to break ties in the case of a misconfiguration)
 
Q: What happens if one of the device’s got rebooted and joined the failover pair after period of being in down state?
The new device joins the Failover pair as a secondary device unless this device is configured as Primary with “Primary Reclaim” is enabled
 
Q: Does SDWAN failover frequently due to stability issues
No, it’s not possible to trigger the failover frequently. SDWAN HA state doesn't change frequently and minimum 120 seconds interval is mandatory to trigger any failover