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@centos.org [mailto:centos-virt- bounces@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:
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
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