How can web browser switch to the next alive SWG proxy server smoothly by wpad.dat proxy script quickly/seamlessly?

Hi,

Web brower can switch to the next alive SWG proxy server by PAC file.

wpad.dat file of web browser contains a JavaScript function “FindProxyForURL()” to determine the address of SWG server. By returning the multiple SWG proxy servers of FindProxyForURL(), for example :

return "PROXY proxy1.example.com:8080; PROXY failover.example.com:8080".

Web browser will use failover.example.com as the secondary SWG proxy when proxy1.example.com is down.

However, it takes around 20 seconds to switch to failover.example.com.

Is there any failover implementation approach of SWG to achieve quick failover result ?

Best Regards

Mike