The collector does not receive sFlow samples from specific Layer 3 VLAN-tagged interfaces on Junos OS| Junos OS EVO platforms

• The affected physical interfaces are operational and carry traffic.
• Interface statistics and SNMP monitoring show traffic on the affected ports.
• show sflow interface displays sampling as enabled.
• The collector receives sFlow datagrams from other interfaces, but flow samples associated with the affected interfaces are missing.

user@switch> show sflow interface

Interface     Status       Sample       Adapted      Polling

                    rate       sample rate     interval

        Egress Ingress   Egress  Ingress   Egress  Ingress

et-0/0/0.2   Enabled Enabled  100  100    100  100 >>>>> it's enabled but samples are not sent to collector

• Removing and reapplying the same sFlow configuration does not resolve the issue.

    et-0/0/0{
        vlan-tagging;  >>>>>>>>>>> vlan tagging
        mac xx:xx:xx:xx;
        }
        unit 2{
            vlan-id 2;
            family inet { >>>>> L3 interface
                address x.x.x.x/24
            }
        }
    sflow {
        agent-id <collector's IP>;
        polling-interval 20;
        sample-rate {
            ingress 100;
            egress 100;
        }
        source-ip <switch's local iP>;
        collector <collector's IP> {
            udp-port 6343;
        }
        interfaces et-0/0/0.2;
    }

Juniper’s general sFlow configuration documentation states:

You cannot enable sFlow technology on a Layer 3 VLAN-tagged interface.

Therefore, this is an expected behavior, avoid adding this type of interfaces in the sFLOW config

Example: Configure sFlow Technology to Monitor Network Traffic | Junos OS | Juniper Networks

Example: Configure sFlow Technology to Monitor Network Traffic | Junos OS | Juniper Networks