[Samba] Re: Unusable performance over WAN (part 2)

[James Lamanna]

On 10/8/07, James Lamanna <jlamanna at gmail.com> wrote:
> On 10/8/07, James Lamanna <jlamanna at gmail.com> wrote:
> > On 10/7/07, James Lamanna <jlamanna at gmail.com> wrote:
> > > On 10/7/07, James Lamanna <jlamanna at gmail.com> wrote:
> > > > On 10/7/07, Volker Lendecke <Volker.Lendecke at sernet.de> wrote:
> > > > > On Sun, Oct 07, 2007 at 09:31:23AM -0700, James Lamanna wrote:
> > > > >
> > > > > > Server sends 1500 byte packet
> > > > > > Client sends 52 bye ACK
> > > > > > Server sends 1500 byte packet
> > > > > > Client sends 52 byte ACK
> > > > > > etc..
> > > > > >
> > > > > > Can anyone think of a reason for this?
> > > > >
> > > > > I did not find a link spontaneously, but Windows sometimes
> > > > > falls back to something that we call "rabbit pellet"
> > > > > mode. Maybe google shows up something for you.
> > > > >
> > > > > Volker
> > > > >
> > > > >
> > > >
> > > > I actually see that behavior using smbclient from a linux machine, so
> > > > its not necessarily Windows related.
> > > >
> > > > -- James
> > > >
> > >
> > > I've put some tcpdump logs from my macbook up at:
> > > http://emagiccards.com/james/tcpdump-vpn-logs.tar.bz2.
> > > It contains 2 files:
> > >
> > > vpn-wan.log - Transferring a file from my macbook over the WAN (logged
> > > in through VPN)
> > > vpn-nowan2.log - Transferring a file from my macbook not over the WAN
> > > (logging through VPN)
> > > (I have separate VPN servers on each size of the WAN).
> > >
> > > Here are the smbclient outputs:
> > >
> > > No WAN:
> > > getting file \Jun07.xls of size 2321920 as Jun07.xls (23.8 kb/s)
> > > (average 23.8 kb/s)
> > >
> > > Using WAN:
> > > getting file \Jun07.xls of size 2321920 as Jun07.xls Short read when
> > > getting file \Jun07.xls. Only got 1032192 bytes.
> > > Error Call timed out: server did not respond after 20000 milliseconds
> > > closing remote file
> > > (3.9 kb/s) (average 3.9 kb/s)
> > >
> > > -- James
> > >
> >
> > I've put up more logs this morning sans VPN.
> > They are in:
> > http://emagiccards.com/james/tcpdump-novpn-logs.tar.bz2
> >
> > Both of these logs are from being directly plugged in on either side of the WAN.
> > The 'nowan' log is the normal, fast transfer, whereas the 'wan' log is
> > over the WAN and has the unusable throughput.
> >
> > -- James
> >
>
> Another point of information:
>
> Samba (and only Samba, other protocols work fine) seems to drop a lot
> of packets.
> Looking at simultaneous tcpdump traces from both the server and client
> side, I see that lots of packets are dropped that are going from the
> samba server to the client.
> The sequence numbers look like this in some cases:
>
> Client Recv                        Server Send
> 1150                                      1150
> 1152                                      1152
>                                              1154
>                                              1156
>                                              1158
>                                              1160
>                                              1162
> 1164                                      1164
> 1166                                      1166
> 1168                                      1168
> 1170                                      1170
>
> So in that case, a whole 5 packets were missed.
> I'm going to assume this isn't normal behavior, and other protocols
> (scp / ftp) don't seem to suffer from this problem.
>
> -- James
>

Of course, it could also be tcpdump dropping packets too :)