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Hig-latency networks and MS file transfers

We have a high-latency WAN connection (MPLS), with 40Mb/s bandwidth. Depending upon where in the world the two endpoints are, the latency varies between 50ms and 600ms.

File transfers using Windows XP / 2000 systems is limited to 3 Mb/s between North Americ and Europe because of the 120 ms latency. With a protocol sniffer, we see about 50K sent in 3 ms, followed by a 120 ms delay while it waits for an acknowledgement.

I understand the limitations of SMB and that SMB2 in Vistal addresses high-latency WAN connections. I've set up a packet shaper (Linux kernel and MasterShaper) to demonstrate the problems in our lab. So I have 3 questions:

1. What kind of improvements have people seen with Vista?
2. Has anyone come up with tweaks to Windows to improve the performance?
3. Is anyone using alternate protocols to share files to address this problem (ie. NFS)?
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Hugh Fraser
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Hugh Fraser
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Bill BachPresidentCommented:
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Hugh FraserConsultantAuthor Commented:
Currently, our environment has a few hundred sites around the world, and a few hundred thousand computers. Scalability is a big issue, and at this time I'm looking for solutions that will allow computers to connect to each other. It may very well be that we need to look for alternate architectures for sharing files. At first glance the solutions you've specified look like client server apps, which will be difficult to scale. But I will certainly follow up with them to see if there's a configuration that can work.

On a broader scale, Windows file transfers are only one connection I'm concerned about. I'm also concerned about client / server apps hosted at various locations, such as multimedia web content, etc..
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Bill BachPresidentCommented:
Any client-server app running across a high-latency link will be painful.
You may wish to look into remote office file cache devices for file sharing, and eith Citrix or TermServer for CS apps.
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Hugh FraserConsultantAuthor Commented:
We've seen some high-latency pain already. We're using Citrix and TS now for limited remote access. We haven't tried client server apps yet, but have seen the effect on web access speed. What triggered the problem for us was the need to transfer about 400Mb of data from Canada to Luxembourg. But while some things are painful, other things just plain fail, and those I'm more concerned about. In the case of the file transfer, mapped drives regularly go offline during transfers.

My understanding is that some of the major changes in SMB version 2 address high-latency WAN connections. Perhaps, Vista and Windows 2008 are the only answer, but I hope not. I'm hoping there are some tweaks or other solutions that won't require us to deploy and support an infrastructure of special servers around the world.

But it may be that your suggestions, or something like NFS may be the only solutions.
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