[FreeBSD 8.2 amd64 XENHVM] DomU terrible network performance trought NAT

[Guillaume Seigneuret]

I think you should try totally disable the window sizing both parts to
isolate it doesn't come from here :
On your FreeBSD VM : sysctl net.inet.tcp.rfc1323=0
On your Linux box : sysctl net.ipv4.tcp_window_scaling=0

Then if the rate is hugely better, try some settings to increase the
compatibility.
You can also try an *iperf *test with TCP and UDP packets to see if the
behavior is generalized, and see what latency you have both part of the
network.

Cordialement,
*Guillaume Seigneuret*



*Network and System Security Architect
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2011/5/12 Michael MacLeod <mikemacleod at gmail.com>

> Try -rxcsum as well. I have both disabled on my domU.
>
> On Thu, May 12, 2011 at 12:53 PM, laurent.cligny at gmail.com <
> laurent.cligny at gmail.com> wrote:
>
> > Le 12/05/2011 17:02, Tobias P. Santos a écrit :
> > > Try this:
> > >
> > > ifconfig xn1 -txcsum
> > >
> > > Best regards,
> > > Tobias.
> > Hello Tobias,
> >
> > Unfortunately ifconfig xn1 -txcsum didn't give me lot of result.
> > Doing this my network perf through NAT is about 7KiB/s (that is better
> > than before, but still unworkable).
> >
> > Thanks for the idea, maybe we are not that far away from the solution.
> >
> > >
> > >
> > > Laurent Cligny wrote:
> > >> Hello all,
> > >>
> > >> I want to setup a FreeBSD DomU VM as a network NAT gateway in order to
> > >> provide Internet access to other FreeBSD and Linux DomU VMs.
> > >> My Dom0 is Xen Cloud Platform 1.0 on a Dell Poweredge 210 with 8
> cores,
> > >> 16GiB RAM and one NIC.
> > >>
> > >> All FreeBSD VM are 8.2 amd64 with XENHVM kernel anf the Linux VM is a
> > >> Paravirtualized Debian amd64.
> > >>
> > >> The NAT gateway is a two-NIC box, with one (xn0) configured with a
> > >> public Internet address and the other (xn1) configured with a class A
> > >> private address (10.0.0.254).
> > >> The Internet traffic is very good from my FreeBSD NAT gateway to the
> > >> Internet (~ 50MiB/s) and also between other VMs on the private network
> > >> (~ 70MiB/s trough scp) after applying the patch here
> > >> (http://www.mail-archive.com/freebsd-xen@freebsd.org/msg00855.html)
> > >> fixing the "too many frags" problem.
> > >>
> > >> Here is a schema of my setup with the observed net speed on it:
> > >>
> > >> ----------         ---------------         ----------------------
> > >> |Internet|---xn0---|FBSD DomU NAT|---xn1---|FBSD and Linux DomUs|
> > >> ----------         ---------------         ----------------------
> > >>           <------->               <------->
> > >>            50MiB/s                 70MiB/s
> > >>
> > >>           <------------------------------->
> > >>            0KiB/s <network speed< 5 KiB/s
> > >>
> > >> [...]
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