So I might have been misinterpreting things here and might be way off base. I think you can ignore this thread and I'll follow up if I get anything concrete down the road =) The retranmissions I'm seeing and reproducing are probably within normal allowances and can't reproduce the issue that originally lead me down this path. - Nathan > -----Original Message----- > From: centos-virt-bounces at centos.org [mailto:centos-virt- > bounces at centos.org] On Behalf Of Nathan March > Sent: Wednesday, April 15, 2015 1:13 PM > To: 'Discussion about the virtualization on CentOS' > Subject: Re: [CentOS-virt] Seeing dropped packets / tcp retrans on latest > 4.4.1-10el6 > > Hi All, > > Some more data on this, I've reproduced this on another host that's a > completely stock centos/xen deployment with a centos 6.6 domU. > > Since I’m seeing the retransmissions on the VIF, I don't think it's related to > the network stack but just in case.. Each host is connected via LACP with vlan > tagging to a pair of stacked cisco 3750's. Host networking config is here: > > http://dpaste.com/1Q6NY3Y > > The vm is on br99 here. > > This is easily reproducable by just generating a 250mb random file and doing > an scp, while watching with tshark: > > tshark -R "tcp.analysis.retransmission" > > There's no visible impact to the connection the vast majority of the time, > which is why I think this has gone unnoticed. > > Just to confirm this wasn't related to hardware / nics, I've reproduced this on: > > - Dell PowerEdge M620 with broadcom nics > - Dell C6220 with intel nics > - Supermicro X8DTT with intel nics > > Any ideas? =) > > - Nathan > > _______________________________________________ > CentOS-virt mailing list > CentOS-virt at centos.org > http://lists.centos.org/mailman/listinfo/centos-virt