Technical Tip: Outgoing traffic not showing for EMAC VLAN

Description 

This article describes outgoing traffic behavior that may be encountered on FortiOS versions up to v7.4.11, v7.6.6, and v8.0.0 when using the EMAC VLAN interface. In particular, no transmitted packets (outgoing traffic) are registered as TX packets, and it is reflected on the related GUI widget also that will not show any TX packets. 

The FortiGate is not showing TX counters on the EMAC VLAN, even though it can be confirmed that packets are both being sent and received on this interface. 

Scope 

FortiGate.

Solution 

fnsysctl ifconfig EMAC_VLAN 

EMAC_VLAN Link encap:Ethernet HWaddr 11:00:00:00:01:12 
inet addr:123.123.123.123 Bcast:123.123.123.255 Mask:255.255.255.240 
link-local6: fe80::4c3a:1ff:fe81:8ed8 prefixlen 64 
UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1 
RX packets:63704156907 errors:0 dropped:0 overruns:0 frame:0 
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 
collisions:0 txqueuelen:1000 
RX bytes: 25000000000000 (25000 GB) TX bytes:0 (0 Bytes) 

diagnose sniffer packet any “ ” 4 0 a 

2025-10-10 7:05:01.947892 EMAC_VLAN out 111.111.111.111.53605 -> 222.222.222.222.443: udp 1250 

config system interface 
...
    edit "LAN_INT" 
        set vdom "root" 
        set vlanforward enable 
        set type aggregate 
        set member "x3" "x4" 
        set monitor-bandwidth enable 
        set role lan 
        set snmp-index 84 
    next 
...
    edit "EMAC_VLAN" 
        set vdom "border01" 
        set ip 123.123.123.123 255.255.255.240 
        set allowaccess ping 
        set type emac-vlan 
        set alias "Internet border01" 
        set estimated-upstream-bandwidth 6000000 
        set estimated-downstream-bandwidth 6000000 
        set monitor-bandwidth enable 
        set role wan 
        set snmp-index 749 
        set interface "VLAN_INT" 
    next 
... 
    edit "VLAN_INT" 
        set vdom "root" 
        set estimated-upstream-bandwidth 6000000 
        set estimated-downstream-bandwidth 6000000 
        set monitor-bandwidth enable 
        set role wan 
        set snmp-index 748 
        set interface "LAN_INT" 
        set vlanid 4049 
    next 

This behavior can be confirmed by: 

1. Confirming there is outgoing traffic.

• Confirming that the traffic logs show the outgoing traffic.

• The output of the commands and 'diagnose sniffer packet any “ ” 4 0 a' shows the outgoing packets. 
  
  

2. Confirm no TX packets are registered on the EMAC VLAN interface:

• From the CLI, run 'fnsysctl ifconfig <port-name>' and verify there is no traffic on the TX packets:0 line.

• From the GUI, add the widget interface that shows the bandwidth usage for the EMAC VLAN Interface, and that there is no traffic for the outbound section.

This behavior is planned to be fixed in FortiOS v7.6.7 and v8.0.1.