(DUP!) ping issue

[lumox]

Hi,
I don't know if it is the right place to ask this question because the problem can be due to some thing else completely, I mean not Proxmox, but
you have to start somewhere, right?

Before I deploy a new setup on my real home lab, I gave it a go on my Vmware workstation first:
I created 3 VMs: a GNS3 VM to run a Mikrotik device, a Proxmox VM, and a Windows VM to manage the Proxmox VM. I set up Vlans (100 and 200) in the MK VM, then I set up the linux bridge (vmbr0) as "vlan-aware" in Proxmox . I then created 2 LXC containers in Proxmox, and set/tagged them on VLAN100 and VLAN200 in their network setup respectively. Ok, everything worked as expected.

However, when I run a ping from LXC 200 to 100, it works, but I get a (DUP!) text at the end of every ping line:

root@debian200:~# ping 192.168.100.200
PING 192.168.100.200 (192.168.100.200) 56(84) bytes of data.
64 bytes from 192.168.100.200: icmp_seq=1 ttl=63 time=126 ms
64 bytes from 192.168.100.200: icmp_seq=1 ttl=63 time=129 ms (DUP!)
64 bytes from 192.168.100.200: icmp_seq=1 ttl=63 time=130 ms (DUP!)
64 bytes from 192.168.100.200: icmp_seq=1 ttl=63 time=130 ms (DUP!)

even when I ping cloudflare:

root@debian200:~# ping 1.1.1.1       
PING 1.1.1.1 (1.1.1.1) 56(84) bytes of data.
64 bytes from 1.1.1.1: icmp_seq=1 ttl=52 time=86.1 ms
64 bytes from 1.1.1.1: icmp_seq=1 ttl=52 time=86.8 ms (DUP!)
64 bytes from 1.1.1.1: icmp_seq=1 ttl=52 time=102 ms (DUP!)

By looking it up on the Internet I found out that it means "duplicate packet". There could be many reasons for this apparently.
One of them could be the particular VLAN setup, but I have no clue about that honestly. As far as I know, another cause may be the particular virtual environment, since I got the same issue when I ping from the Mikrotik Vm running in GNS3 to a VM, but no problem when I ping cloudflare from the same Mikrotik device.

Could you please help me figure this out?
Thanks

 

[mgabriel]

It looks like a misconfigured bond device. If you use bonds, check that both sides are configured correctly.

 

[Irre Levant]

Please check your guest mac addresses. Is it possible that multiple guests using the same MAC so that the host is sending each segment to multiple guests?

 

[lumox]

Please check your guest mac addresses. Is it possible that multiple guests using the same MAC so that the host is sending each segment to multiple guests?

I can't check it anymore now because I deleted the entire project, but you may be right anyway. Thanks for the hint. It might come in handy next time.