SD-WAN Link monitoring via Performance SLA ICMP

Forum|Forum|10 days ago
July 8, 2026
2 replies
43 views

Dear community,

I need you support on the following items

I have been asked to configure link health monitoring for our networks, now I have already setup the Performance SLA using ICMP Ping to check if the link is up and/or down. this will check if the link is up alright, now if the link goes down then using the SD-WAN rules the connection should swing the other ISP link and avoid any distruptions that might happen or it should not require manual switch.

Now first question is here that what do you suggesst be the minimum link status to avoid any kind of routing issues later

Now the second issue is that when configure SD-WAN rules which interface selection strategy should I use because when I read through the docs they mentioned to use the Manual but it does not allow for selecting any SLA rules you have configured, now out of the Best Quality and Lowest cost which one should I use?

Can you please advise on this as well.

I am looking forward to hearing from you.

Best Regards,

Shah.

E

evok1ng

New Member

What specific type of traffic (e.g., general web browsing, VoIP, video conferencing) are you primarily trying to protect with this SD-WAN rule?

ShahAlizadaAuthor

New Member

Hey @evok1ng

This is for all types of traffic no specific type of traffic, we have multiple VLANs and some VLANs are set to go through one ISP and some others are set to go via another ISP.

Now we also want to have link health check to make sure if the links fail we detect and switch between ISPs automatically.

Now we have to make sure we maintain the order through which ISP the traffic is sent for specific VLAN while also maintaining the link monitoring if in case it fails.

Tks.

E

evok1ng

New Member

Hi Shah,

Definitely go with Lowest Cost (SLA). It's much more stable for general failover. "Best Quality" can sometimes cause route flapping if both links have similar latency, which will drop your sessions.

Since you need specific VLANs on specific ISPs, just create multiple SD-WAN rules based on their Source IPs.

For example: Create Rule 1 for the VLANs that prefer ISP-1. Set the source to those VLAN subnets, use Lowest Cost (SLA), and set the interface preference to ISP-1 first, then ISP-2. Then create Rule 2 for the VLANs that prefer ISP-2. Set the source to those VLAN subnets, but swap the interface preference (ISP-2 first, then ISP-1).

Just tie both rules to a single Performance SLA (e.g., ping 8.8.8.8) that monitors both ISPs. Lastly, ensure you only have one default route (0.0.0.0/0) pointing to the SD-WAN zone, and the rules will handle the automatic failover perfectly.

Cheers.

Toshi_Esumi

SuperUser

The “Link Status” setting is just for interval and consecutive downs or ups to decide status changes. Those are the setting how quick you want the failover/failback to happen. With the default setting failover/falback time = 2.5 - 3 sec/2.5 - 3 sec. But ping/ping reply packets happen every 500ms on the circuit. If it’s a metered circuit like 4G/5G circuit, you might want to reduce the frequency by sacrificing the failover/failback time.

Toshi

Sign up

Login with SSO

Login to the community

Login with SSO