Symptom
Bundle interfaces with EVPN ethernet-segment are not kept down during during system initialization after a reload. Interfaces may briefly come up before EVPN programs it as down, causing a few seconds of traffic loss.
Conditions
Perform node reload with EVPN configured using bundle ethernet-segments
Workaround
If evpn cost-out is configured before reload is performed, bundle-interfaces will not flap during initialization
Further Problem Description
Normal EVPN operation during a reload is to force all Bundle-ether interfaces with EVPN ethernet-segments configured to remain down during system initialization. This will prevent any ingress traffic from connected CE devices from forwarding traffic to the PE until the system is programmed and able to correctly forward EVPN traffic. However, it was found that based on certain timing of events during bringup, Bundle-interfaces were allowed to briefly come up and attract ingress traffic before EVPN programmed them as down, resulting is a few seconds of transient traffic loss.
