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To: CIPE <cipe-l,AT,inka,DOT,de>
Subject: Re: Checklist (sub-thread of: "Slow file sharing performance: lostpidgeons")
From: James Knott <james.knott,AT,rogers,DOT,com>
Date: Tue, 09 Sep 2003 08:09:37 -0400
In-reply-to: <Pine.LNX.4.44.0309091037440.4697-100000@tiiger.kivilinn.tartu.ee>
References: <Pine.LNX.4.44.0309091037440.4697-100000@tiiger.kivilinn.tartu.ee>

Tanel wrote:
On Mon, 8 Sep 2003, James Knott wrote:

I used dial up, the problems return. This only appears to apply to protocols that use UDP. FTP, which uses TCP, doesn't experience that problem. My conclusion is that the problem is with Samba & NFS and not CIPE. I would expect this is due to the lack of UDP flow control, except as may be provided by a particular service. My experience, where file sharing from the notebook backs this up, as data from the notebook would be initially limited by the dialup connection and there would be no concern about over-running some slower device further on.

that's why I suggested not to use UDP protocol for VPN. UDP is slow with slow network connections and is extremely dependent of packet loss and ping time. I always get lower speeds with UDP rather than TCP/IP, on the same connection. FTP transfer is always ca 30-40% faster than UDP transfer (NFS or Cipe VPN), even on fibre cable connections. And I think there's nothing to do to make things better.

Please explain the performance differences, between using UDP to carry packets and just placing those packets directly on an ethernet frame. Both are "best effort" with no flow control. UDP will add another header, but beyond that, there's no difference in how the packets are handled.

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