Symptom

On a Rosen MLDP Core router behaving as mid node carrying Data MDT, on adding/removing remote receivers or adding/removing local receivers the following symptoms were observed: 1) Permanent traffic loss to local receivers or 2) Permanent traffic loss to remote receivers or 3) Temprorary traffic loss to remote receivers

Conditions

This issue was observed when the ingress and egress interfaces were on different linecards in a multi slot chassis. The temporary traffic loss issue is confirmed to happen when ingress and egress are on different LC, but the permanent traffic loss could happen without this condition (when above trigger is performed) It was also seen that the issue is more prominent when the core router transitions from/to mid/bud role.

Workaround

Permanent traffic loss can be prevented by permanently adding a local receiver on a egress LC interface using a static join for the affected multicast route. This will force the core router to be in the bud role minimizing the switching of roles between bud/mid.

Further Problem Description