SwOS • Weird: Monitoring EGRESS traffic of a trunk port does not show VLAN IDs

Hello,

I realized a rather straight forward setup of connecting two switches
Switch1: TP-Link SG3452
Switch2: CSS610-8G-2S+ (SwOS 2.18)
over a trunk port.
To be more precise I build a LACP of 4 ports and configured this as a trunk to transport only tagged VLANs.
Routing is done by a PFSense connected to Switch1.
For simplification Switch2 can be seen as an extension to get some more access ports or even connect a server by 10G.

After some time I got that to work and the traffic flow I see makes totally sense:
I am able to monitor traffic passing the LAG/Trunk
- on Switch1-side
- on Router-side
- on Switch2-side

BUT there is one open point I tend to call a bug on SwOS side or missing understanding on my personal end.

Monitoring EGRESS traffic of the trunk on switch2 (MT) does not show VLAN IDs at all.
That's weird esp. because on the corresponding INGRESS of switch1 (TPLink) the VLAN IDs are present.

Whereas watching INGRESS on switch2 (MT) shows VLAN-IDs as expected - as EGRESS of switch1 (TPLink) also has it.

I can't get around calling this a bug on SwOS side because it seems to be very unlikely that the EGRESS really misses the VLAN ID because:
1) switch 1 shows VID
2) My config on switch2 (MT) should prevent untagged traffic at all3) traffic arrives tagged on my router

Does have anyone an explanation for this scenario or should I raise a bug report toward MT?

Thanks and best regards,
HF

Statistics: Posted by hansfranz — Tue Mar 26, 2024 5:16 pm

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