Currently when a packet is sampled from the ingress traffic, the output interface index is populated as 0. This is applicable for both unicast and multicast traffic. As part of the Egress sFlow feature, the output interface index is populated with the destination port information for unicast packets sampled in both ingress and egress direction. Because of a hardware limitation, multicast packet samples still have an output interface index as 0.
The following table illustrates the expected output of the ifIndex when based on traffic type, and sampling direction:
| Ingress/Egress, Unicast/Multicast | Scenario |
|---|---|
| Ingress/Unicast | sFlow sample includes both ingress and egress port (ifIndex). |
| Egress/Unicast | sFlow sample includes both ingress and egress port information. |
| Ingress/Multicast | Egress port information cannot be provided because of hardware limitation. Egress if Index will be 0 and ingress if Index is supplied. |
| Egress/Multicast | Egress port information cannot be provided because of hardware limitation. Egress if Index will be 0 and ingress if Index is supplied. |