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I have disabled 802.1Q module in my Cento 7 VM and did arping through one of the interface to it's gateway IP and captured packet traffic on that interface from the same VM.

[root@vm1 ~]# lsmod | grep 8021q
8021q                  33208  0
garp                   14384  1 8021q
mrp                    18542  1 8021q
[root@vm1 ~]# modprobe -r 8021q
[root@vm1 ~]# lsmod | grep 8021q

My expectation was that exgress packets wouldn't have any VLAN tags. The machine I pinged is the windows host and also VLAN tags support was not added in the windows host. So, I also expect that the ingress packets also won't be having any VLAN tags.

But I see VLAN tag with default ID: 1 on both the packets.

So, is the module 8021.q in Centos 7 is obselete and not needed at all?

enter image description here

Edit 1:

I checked again by analyzing ping traffic. For ping, there is no VLAN tag ids added (with and without 8021q module loaded)

enter image description here

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Issue is with the decoding type I have selected. I selected decoding as VLAN for link and then selected decoding as do not decode. Thus somehow ended up with the above wrong decoding.

I just need to clear decoding to see the actual data and the VLAN tag is then added only when the 8021q module is loaded + when a VLAN tagged interface is created.

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