netdev - Re: [rfc 0/3] IPVS: checksum updates

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Message-ID: <20080908114258.GA29477@google.com>
Date:	Mon, 8 Sep 2008 13:42:59 +0200
From:	juliusv@...gle.com (Julius Volz)
To:	Simon Horman <horms@...ge.net.au>
Cc:	lvs-devel@...r.kernel.org, netdev@...r.kernel.org,
	Siim Põder <siim@...rad-teel.net>,
	Julian Anastasov <ja@....bg>,
	Malcolm Turnbull <malcolm@...dbalancer.org>,
	Vince Busam <vbusam@...gle.com>,
	Herbert Xu <herbert@...dor.apana.org.au>
Subject: Re: [rfc 0/3] IPVS: checksum updates

On Mon, Sep 08, 2008 at 08:41:22PM +1000, Simon Horman wrote:
> On Mon, Sep 08, 2008 at 12:03:04PM +0200, Julius Volz wrote:
> > On Mon, Sep 8, 2008 at 4:04 AM, Simon Horman wrote:
> > > Hi,
> > >
> > > The impetus for this series of patches is Julian Anastasov noting
> > > that "load balance IPv4 connections from a local process" checks
> > > for 0 TCP checksums. Herbert Xu confirmed that this is not legal,
> > > even on loopback traffic, but that rather partial checksums are
> > > possible.
> > >
> > > The first patch in this series is a proposed solution to handle
> > > partial checksums for both TCP and UDP.
> > >
> > > The other two patches clean things up a bit.
> > >
> > > I have not tested this code beyond compilation yet.
> > 
> > After some first tests, remote connections are still working, but not
> > local ones from the director. The TCP handshake works and the
> > connection is established, but all following packets arriving at the
> > real server have an incorrect TCP checksum.
> > 
> > Btw., this happens both with and without this last series of patches,
> > so I can't get the local client feature working at all. Looking at it
> > further...
> 
> Ok, is this for both IPv4 & IPv6? Does it still occur with just the first
> patch in this series applied?

It's for both, although I only tested IPv4 at first. Here is a complete
test matrix of what works when:

CR = connection refused
T = connection timeout
C = connection established, but not working afterwards
OK = working

			remote client |	local client
COMMIT			v4	v6    |	v4	v6
======================================|=================
CSUM 3/3		OK	T     |	C	T
CSUM 2/3		OK	T     |	C	T
CSUM 1/3		OK	T     |	OK	T
W/O CSUM		OK	T     |	C	T
...				      |
f2428ed5		OK	T     |	CR	CR
4856c84c		OK	CR    |	CR	CR
f94fd041 (my last one)	OK	OK    |	CR	CR

So the last time that IPv6 was working _at all_ was at my last commit of
the big v6 series...

Julius

-- 
Julius Volz - Corporate Operations - SysOps

Google Switzerland GmbH - Identification No.: CH-020.4.028.116-1
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