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From Remi Bergsma <>
Subject Re: Re[2]: GRE Isolation Performance
Date Thu, 05 Nov 2015 08:45:08 GMT
Hi David,

STT support was added to mainstream OVS only a few months ago, last summer. Before that you
had to patch it in. 

To be honest, in 2012 when we started using this, STT was the only option that could use the
offloading of the nic. Today, VXLAN also is able to do that. For new deployments, that is
the way forward as it is widely adopted and supported. 

I never tried VXLAN without a controller, but it is worth investigating. For sure Nicira and
Nuage support it. 

We might consider dropping GRE support, but that's more of a subject for the dev list. If
you have stats/performance details to share, that might help showing it is not a real option
any more for production deployments. 

Regards, Remi 

Sent from my iPhone

> On 05 Nov 2015, at 08:19, David Amorín <> wrote:
> It looks VXLAN and STT are currently the best options. If OVS has support for STT tunnels,
why CS doesn't support this configuration?
> David
> -----Mensaje original----- 
>> De: "Remi Bergsma" <> 
>> A: 
>> Fecha: 04/11/2015 20:29 
>> Asunto: Re: GRE Isolation Performance 
>> Hi David,
>> I haven’t used GRE myself, but I do know that performance wise you need something
that offloads to the nic, as with vlan tagging (instead of having the cpu do all the work).
Did you consider VXLAN? That has nic offloading support in most nics these days. We are using
STT (also does offloading) with Nicira and it is very fast. If I had to build again, I’d
investigate VXLAN.
>> Regards,
>> Remi
>>> On 04/11/15 12:31, "David Amorín" <> wrote:
>>> Hi all,
>>> We are working in an environment with CS 4.5.2 / XenServer 6.5 with multiple
zones (Spain and Netherlands) using GRE Isolation and we have some concerns that we would
like to share with you. Basically, we make a CPU benchmark between VLAN isolation and GRE
isolation and the results show us that the consumption of CPU with GRE isolation is too much
compared with VLAN isolation.
>>> Can anyone share with us the experience working with GRE isolation?
>>> We are not sure if this configuration in production will be safe, scalable and
with an acceptable level of performance.
>>> Thanks,
>>> David

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