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Re: [Openvpn-users] Performance on Windows Shares


  • Subject: Re: [Openvpn-users] Performance on Windows Shares
  • From: Leonard Isham <leonard.isham@xxxxxxxxx>
  • Date: Fri, 29 Apr 2005 21:19:20 -0400

On 4/29/05, James Yonan <jim@xxxxxxxxx> wrote:
> On Fri, 29 Apr 2005, Ed Russell wrote:
> 
> > Hello all, I have been experimenting with OpenVPN on various Linux systems
> > as hosts.  I have been using OpenVPN 2.0 style configurations on my 2.4
> > kernel systems and 1.6 style configurations on my 2.2 kernel systems.  My
> > kudos go to the entire team as the documentation and product itself is
> > fantastic.  So far, everywhere I have turned and no matter what I have
> > wanted to do the answer is YES YOU CAN...  Quite a refreshing change.
> > However, the biggest thing I have been noticing is that there is a pretty
> > large latency when dealing with Windows shares.  Now I am using routing and
> > I basically want to keep it that way.  So once I connect in to an
> > environment I map a windows share with a net use based upon IP.  I can map
> > no problem whatsoever but navigating the drive is incredibly slow.  I have
> > tried into a DSL environment, into a T1 environment, from a T1 environment,
> > etc etc.  No matter the host or the client bandwidth it usually feels the
> > same.  Is there anything I can do to help tune this, or is just par for the
> > course?  Any feedback would be appreciated.
> 
> The SMB protocol, used for Windows shares, is well known for its bad
> performance over slower links.  The problem is that the protocol was
> originally designed to run over local LANs, and so the developers assumed
> latency would be negligible.  Of course, this isn't true on VPN or WAN
> links, and so the "chattiness" of the protocol takes a toll.
> 

Just to add perspective a full T-1 is 1.5Mbps and most LANs are
100Mbps... So you usually have less that 1.5% of the bandwidth when on
the LAN.

Then you can throw in latency.  To give a visual:
- How long does it take you to walk across an average room and back (LAN)
- Compared to how long it takes you to walk from one end of the block
to the other and back? (WAN)
-- 
Leonard Isham, CISSP 
Ostendo non ostento.