Link monitoring example

Performance SLA link monitoring measures the health of links that are connected to SD-WAN member interfaces by sending probing signals through each link to a server and measuring the link quality based on latency, jitter, and packet loss. If a link is broken, the routes on that link are removed, and traffic is routed through other links. When the link is working again, the routes are reenabbled. This prevents traffic being sent to a broken link and lost.

In this example:

• Interfaces wan1 and wan2 connect to the internet through separate ISPs
• The detection server IP address is 208.91.114.182

A performance SLA is created so that, if one link fails, its routes are removed and traffic is detoured to the other link.

To configure a Performance SLA using the GUI:

1. On the FortiGate, add wan1 and wan2 as SD-WAN members, then add a policy and static route. See SD-WAN quick start for details.
2. Go to Network > SD-WAN, select the Performance SLAs tab, and click Create New.
3. Enter a name for the SLA and select a protocol.
4. In the Server field, enter the detection server IP address (208.91.114.182 in this example).
5. In the Participants field, select both wan1 and wan2.
6. Configured the remaining settings as needed, then click OK.

To configure a Performance SLA using the CLI:

config system sdwan
    config health-check
        edit "server"
            set server "208.91.114.182"
            set update-static-route enable
            set members 1 2
        next
    end
end

To diagnose the Performance SLA status:

# diagnose sys sdwan health-check
Health Check(server):
Seq(1): state(alive), packet-loss(0.000%) latency(15.247), jitter(5.231) sla_map=0x0
Seq(2): state(alive), packet-loss(0.000%) latency(13.621), jitter(6.905) sla_map=0x0