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What would limit max bandwidth usage to 12M on a 1000M circuit

Posted on 2013-11-01
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Last Modified: 2013-11-12
We have a need to transfer about 50GB of data from a Windows 2003 server at a remote site across a gig WAN circuit to a Windows 2008 server at our data center.  When we try to send that traffic over the nearly-empty gig link, bandwidth use never exceeds about 12M or so.  We do use that link for database-syncing, and that process can use about 980Mbps, so the link is fully capable of carrying the traffic.  We suspect bandwidth-delay-product might factor in here, or perhaps some limit built into Windows 2003, but if somone can give us a definitive answer, we would be grateful.
Router hardware: Cisco 3945e on each end for the gig link.
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Question by:hassarfj
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by:alicain
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A few thoughts :
- Are the NICs on the server correctly configured and not auto-detecting to 10Mb?
- Is the 2003 server SP2 with the post SP2 fixes for the Scalable Networking Pack, and the drivers up to date?
- Getting a trace with wireshark or netmon would be useful to see if there are any network issues in there.
- Do a tracert to check that there isn't any odd routing occurring.


Regards,
Alastair.
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by:hassarfj
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Good questions...
We believe the NICs are OK - but will check again
I believe the server is up to date.  Checking that again also.
I have a packet trace file, but need to figure out how to rename it so I can upload it
The routing is fine - tracert hits all the right hop points.

We tried using a 100M backup link, provided by a different carrier, but got the same result, so we ruled out service-providor config issues.
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by:giltjr
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How are you transferring the files?  Have you tried used ftp?

What is the latency between the two sites?
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by:surbabu140977
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You might need to check the 3945 for any probable QoS which might police your traffic at 12meg.......
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by:hassarfj
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Problem as initially reported relates to CIFS file transfers.  
We still get "slow" performance using FTP, but better than CIFS. (Perhaps as much as 30Mbps)
RTT Latency is about 68ms from Sacramento to Hawaii
We checked QoS - no drops reported
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by:alicain
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Do you have a Windows 2008 or Windows 7 machine at the location where the 2003 server is, if so how does that perform?  SMB is so much less chatty in later versions, that you could well see a significant increase in throughput.  

That'd also help with identifying if it's any of the 2003 SNP related issues.  You could disable Task Offloading, which I should have mentioned in the the earlier email :
http://support.microsoft.com/kb/904946
You experience intermittent communication failure between computers that are running Windows XP or Windows Server 2003

Regards,
Alastair.
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by:giltjr
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O.K, you said you have "50GB of data."  Does that mean you have a few large files or a lot of little files?

If you have a lot of little files, say under 100MB, then you will not get the full bandwidth if you are doing one file at a time.  You need to either zip the files into a single large file or start multiple ftp connections and ftp multiple files at once.  If you use an ftp client like Filezille you can set how many transfers at one time you do.
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by:hassarfj
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Files are large - maybe 25GB to maybe 40+GB
Questions remains: why can't we send the big file across the big pipe simply, in a single TCP session, without having to break it up with some app like filezilla?
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by:giltjr
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You don't have to break it up.  I think you misunderstood the point I was trying to make.  I was not suggesting that you break it up.  You originally said you had about 50GB of data to transfer.    I was trying to see if it was one big file, or a lot of little files.

When transferring a lot of little files you can fill the pipe.  

I would try and leave it as a single big file.

What FTP client did you use?

What FTP server are you using?

If you are using the Windows supplied FTP client you may want to try using the following command to start it:

ftp -w:524140
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giltjr earned 300 total points
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Doing a little calculating to fill a 1 Gb pipe with 70ms latency you would need a window size of 8MB.

I'm not sure what the max. window size ftp client supports (the -w: parameter) you may want to try larger numbers.  The value you sepcify for -w: should be a multiple if 1460, assuming that 1460 is your MSS.

You may want to try -w:3500000
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by:giltjr
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Thank you.  What buffer size did you test with and what were the results?
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by:hassarfj
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we gave  up on Win 2003, moved the file to a WIN 2008 unit and copied the 50 GB file to the cdata center using Filezilla, which multi-threaded the transfer.  We are seriously looking into a product called FileCatalyst which can replace ftp and transfer at line speed up to 10G
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by:giltjr
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filezilla uses a larger window size.  However multi threaded would only help if you had more than one file.  Earlier you implied you had a single large file not a lot of smaller files.
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