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How does the Elfiq Link Balancer detect a problem on a WAN/Internet link?

April 26, 2017balancer detect elfiq internet link problem WAN

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How does the Elfiq Link Balancer detect a problem on a WAN/Internet link?

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The Link Balancer checks the status of each WAN link every 3 seconds (default value). During that time, three TCP sessions are conducted for each of the destinations configured in an ISP.Therefore, every 3 seconds a SYN, SYN-ACK, RST sequence is done on each ISP, to the destination of the next hop for that link. The response time (RTT) to this hop is then calculated.If the first hop does not answer, the Link LB will try to contact the second hop. If the second one does not answer, the ISP is automatically deactivated and the network traffic is dynamically redistributed to the other links.