Load Balancing on cEdge with two tunnels

[Kamran Mustafayev]

Hey everyone,

We recently built and SD WAN network from scratch based on private circuits, basically on our cEdge side we have two TLOC - lets say Private1 and Private2, on the Hub (we have two of them) we are using same color called "mpls",  we have a functioning network with all DTLS and IPsec tunnels up

Lets say we have one MPLS carrier is 1G and second one is 100mb (don't ask me why) - in this case as per my understanding default ECMP settings will work, i.e traffic will be separated equally and at some point second circuit (100mb) should be saturated 

Question: I know there is some ways like changing preferences or weight, but is there any native logic at SD WAN plane when it see that second link is saturated and it should automatically switch flows to 1G link ? 

Thank you.

[MHM Cisco World]

Use Weight 

check this link for more info

https://www.thenetworkdna.com/2021/02/the-role-of-preference-and-weight-in.html

[pietro manicioto]

If this is a common and consistent thing, then you can use weight. If your circuits are all over the place size wise and color wise, weight is going to be more of a nightmare than you will want to deal with. You can set preferences in app aware routing and other mechanisms, but that means defining applications with Cisco's half crocked application families. 

Logic and Cisco SDWAN do not go together in the same sentence if you want me to be bluntly honest. 

[Kanan Huseynli]

Hi,

there is no such technique i.e use bandwidth % can not impact path decision. If the main purpose is redundancy, then just use 1G link as preferred (like active/hot standby routing).

Just additional comment for critical application you may use both (but you need advertise prefix related to critical apps with the same "cost" which basically means you need ECMP) with AAR.

All above can be done via centralized policies.

[dijix1990]

Maybe you need to use per tunnel qos? https://www.cisco.com/c/en/us/td/docs/routers/sdwan/configuration/qos/ios-xe-17/qos-book-xe/per-tunnel-qos.html

https://www.youtube.com/watch?v=yoNqkVIq59U