[pve-devel] lost tcp packets in bridge

Alexandre DERUMIER aderumier at odiso.com
Tue Aug 22 08:16:25 CEST 2017

Hi Stefan,

No I don't have this behaviour. I only remember probleme with old debian wheezy with kernel 3.2,
where I had this kind of problem. (seem to be a problem in virtio-net driver in 3.2)

Do you known exactly where the packet is lost ? (do you have used tcpdump on tap interface too ?)

mtu size is enough big on bridge && taps vs mtu in your vms ?

----- Mail original -----
De: "Stefan Priebe, Profihost AG" <s.priebe at profihost.ag>
À: "pve-devel" <pve-devel at pve.proxmox.com>
Envoyé: Mardi 22 Août 2017 08:04:18
Objet: [pve-devel] lost tcp packets in bridge


while running PVE 4.4 i'm observing lost tcp packets on a new cluster. 
Two VMs are connected to the same bridge on the same host using virtio 
and linux as a guest. 

But the target guest does not receive all tcp packets some get lost. I 
see them leaving on the source using tcpdump but they do not arrive at 
the target network card (checked using tcp dump). This results in 
sometimes awfully slow performance as tcp retransmits happen. 

I already flushed all iptables rules - but this did not help. I can't 
reproduce the issue it just happens "sometimes" with some packets. 

Has anybody already ovserved something like this? 

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