Mailing List Archive: [lvs-users] HTTP Uploads failing when traffic via CloudFlare

[lvs-users] HTTP Uploads failing when traffic via CloudFlare

Jul 2, 2014, 6:49 AM

Post #1 of 4 (1665 views)

Hi,

We have a setup - 1 director and 2 real servers and LVS TUN is used
because they're located at different places.

Now, the problem is that whenever someone tries to upload a large
image (~400 KB) via CloudFlare, it just gets stuck and fails. The same
works when I do it directly.

Tried contacting CloudFlare, and they say everything is right on their side.

I suspect this has something to do with LVS Tun. What could be the problem?

Tried setting MTU = 1400 as per
http://www.austintek.com/LVS/LVS-HOWTO/HOWTO/LVS-HOWTO.LVS-Tun.html#setting_mtu_by_route
but that doesn't help either.

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Re: [lvs-users] HTTP Uploads failing when traffic via CloudFlare [ In reply to ]

me at nileshgr

Jul 2, 2014, 11:24 AM

Post #2 of 4 (1617 views)

Permalink

On Wed, Jul 2, 2014 at 7:19 PM, Nilesh Govindrajan <me@nileshgr.com> wrote:
> Hi,
>
> We have a setup - 1 director and 2 real servers and LVS TUN is used
> because they're located at different places.
>
> Now, the problem is that whenever someone tries to upload a large
> image (~400 KB) via CloudFlare, it just gets stuck and fails. The same
> works when I do it directly.
>
> Tried contacting CloudFlare, and they say everything is right on their side.
>
> I suspect this has something to do with LVS Tun. What could be the problem?
>
> Tried setting MTU = 1400 as per
> http://www.austintek.com/LVS/LVS-HOWTO/HOWTO/LVS-HOWTO.LVS-Tun.html#setting_mtu_by_route
> but that doesn't help either.

Okay some info on the MTU thing, I was seeing ICMP frag required
messages in tcpdump on director.
As per the guide, I changed MTU of outgoing interface on real servers
to 1480 and changed MTU of tunnel to 1500. It stopped those messages
and now I see lot of packets with F flag possibly indicating that
fragmentation works correctly. But uploads still don't work.

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Re: [lvs-users] HTTP Uploads failing when traffic via CloudFlare [ In reply to ]

malcolm at loadbalancer

Jul 3, 2014, 3:50 AM

Post #3 of 4 (1617 views)

Permalink

Nilesh,

How long does the upload take?
Its not a simple question of TCP time out?

Take a look at :
http://www.austintek.com/LVS/LVS-HOWTO/HOWTO/LVS-HOWTO.services.general.html#tcpip_idle_timeout

On 2 July 2014 19:24, Nilesh Govindrajan <me@nileshgr.com> wrote:

> On Wed, Jul 2, 2014 at 7:19 PM, Nilesh Govindrajan <me@nileshgr.com>
> wrote:
> > Hi,
> >
> > We have a setup - 1 director and 2 real servers and LVS TUN is used
> > because they're located at different places.
> >
> > Now, the problem is that whenever someone tries to upload a large
> > image (~400 KB) via CloudFlare, it just gets stuck and fails. The same
> > works when I do it directly.
> >
> > Tried contacting CloudFlare, and they say everything is right on their
> side.
> >
> > I suspect this has something to do with LVS Tun. What could be the
> problem?
> >
> > Tried setting MTU = 1400 as per
> >
> http://www.austintek.com/LVS/LVS-HOWTO/HOWTO/LVS-HOWTO.LVS-Tun.html#setting_mtu_by_route
> > but that doesn't help either.
>
> Okay some info on the MTU thing, I was seeing ICMP frag required
> messages in tcpdump on director.
> As per the guide, I changed MTU of outgoing interface on real servers
> to 1480 and changed MTU of tunnel to 1500. It stopped those messages
> and now I see lot of packets with F flag possibly indicating that
> fragmentation works correctly. But uploads still don't work.
>
> _______________________________________________
> Please read the documentation before posting - it's available at:
> http://www.linuxvirtualserver.org/
>
> LinuxVirtualServer.org mailing list - lvs-users@LinuxVirtualServer.org
> Send requests to lvs-users-request@LinuxVirtualServer.org
> or go to http://lists.graemef.net/mailman/listinfo/lvs-users
>

--
Regards,

Malcolm Turnbull.

Loadbalancer.org Ltd.
Phone: +44 (0)330 1604540
http://www.loadbalancer.org/
_______________________________________________
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Re: [lvs-users] HTTP Uploads failing when traffic via CloudFlare [ In reply to ]

me at nileshgr

Jul 3, 2014, 4:28 AM

Post #4 of 4 (1620 views)

Permalink

On 03-Jul-2014 4:33 pm, "Malcolm Turnbull" <malcolm@loadbalancer.org> wrote:
>
> Nilesh,
>
> How long does the upload take?
> Its not a simple question of TCP time out?
>
> Take a look at :
>
http://www.austintek.com/LVS/LVS-HOWTO/HOWTO/LVS-HOWTO.services.general.html#tcpip_idle_timeout
>
>
>
>
>
>
> On 2 July 2014 19:24, Nilesh Govindrajan <me@nileshgr.com> wrote:
>
> > On Wed, Jul 2, 2014 at 7:19 PM, Nilesh Govindrajan <me@nileshgr.com>
> > wrote:
> > > Hi,
> > >
> > > We have a setup - 1 director and 2 real servers and LVS TUN is used
> > > because they're located at different places.
> > >
> > > Now, the problem is that whenever someone tries to upload a large
> > > image (~400 KB) via CloudFlare, it just gets stuck and fails. The same
> > > works when I do it directly.
> > >
> > > Tried contacting CloudFlare, and they say everything is right on their
> > side.
> > >
> > > I suspect this has something to do with LVS Tun. What could be the
> > problem?
> > >
> > > Tried setting MTU = 1400 as per
> > >
> >
http://www.austintek.com/LVS/LVS-HOWTO/HOWTO/LVS-HOWTO.LVS-Tun.html#setting_mtu_by_route
> > > but that doesn't help either.
> >
> > Okay some info on the MTU thing, I was seeing ICMP frag required
> > messages in tcpdump on director.
> > As per the guide, I changed MTU of outgoing interface on real servers
> > to 1480 and changed MTU of tunnel to 1500. It stopped those messages
> > and now I see lot of packets with F flag possibly indicating that
> > fragmentation works correctly. But uploads still don't work.
> >
> > _______________________________________________
> > Please read the documentation before posting - it's available at:
> > http://www.linuxvirtualserver.org/
> >
> > LinuxVirtualServer.org mailing list - lvs-users@LinuxVirtualServer.org
> > Send requests to lvs-users-request@LinuxVirtualServer.org
> > or go to http://lists.graemef.net/mailman/listinfo/lvs-users
> >
>
>
>
> --
> Regards,
>
> Malcolm Turnbull.
>
> Loadbalancer.org Ltd.
> Phone: +44 (0)330 1604540
> http://www.loadbalancer.org/
> _______________________________________________
> Please read the documentation before posting - it's available at:
> http://www.linuxvirtualserver.org/
>
> LinuxVirtualServer.org mailing list - lvs-users@LinuxVirtualServer.org
> Send requests to lvs-users-request@LinuxVirtualServer.org
> or go to http://lists.graemef.net/mailman/listinfo/lvs-users

It's not a normal time out because I'm on a 24 Mbps connection and my
server has 1 Gbit.
When I connect to the real servers directly, it works. I'm trying to upload
a 500 KB image which uploads in a very short time. When uploading via
director, it just stalls indefinitely and then times out.
_______________________________________________
Please read the documentation before posting - it's available at:
http://www.linuxvirtualserver.org/

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Send requests to lvs-users-request@LinuxVirtualServer.org
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