In scenarios where a WAN edge router has multiple colors that meet the SLA, we can also define multiple preferred colors as highlighted in the output below:
policy
app-route-policy APP-ROUTE-POLICY
vpn-list VOIP
sequence 11
match
dscp 46
!
action
sla-class VOIP-SLA preferred-color biz-internet mpls
!When multiple preferred-colors are configured, the policy tries to load-balance the data traffic across all preferred colors that satisfy SLA. Let’s say all cEdge-6 local colors meet SLA. The router load balances the traffic over the biz-internet and mpls because they are configured as preferred.
If, at some point, only one of the preferred colors meets SLA, the router pins the traffic to that color.
Again, if at some point no preferred color meets the SLA, the WAN edge router will load-balance the data traffic across all available tunnels regardless of the SLA (app-route is a positive policy).