| 1 | <?xml version='1.0' encoding='UTF-8'?>
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| 2 | <!DOCTYPE topic PUBLIC "-//OASIS//DTD DITA Topic//EN" "topic.dtd">
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| 3 | <topic xml:lang="en-us" id="nat-adv-settings">
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| 4 | <title>Tuning TCP/IP Buffers for NAT</title>
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| 5 |
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| 6 | <body>
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| 7 | <p>
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| 8 | The <ph conkeyref="vbox-conkeyref-phrases/product-name"/> NAT stack performance is often determined by
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| 9 | its interaction with the host's TCP/IP stack and the size of
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| 10 | several buffers, <codeph>SO_RCVBUF</codeph> and
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| 11 | <codeph>SO_SNDBUF</codeph>. For certain setups users might
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| 12 | want to adjust the buffer size for a better performance. This
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| 13 | can by achieved using the following commands, where values are
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| 14 | in kilobytes and can range from 8 to 1024:
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| 15 | </p>
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| 16 | <pre xml:space="preserve">$ VBoxManage modifyvm <varname>VM-name</varname> \
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| 17 | --natsettings1 16000,128,128,0,0</pre>
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| 18 | <p>
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| 19 | This example illustrates tuning the NAT settings. The first
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| 20 | parameter is the MTU, then the size of the socket's send buffer
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| 21 | and the size of the socket's receive buffer, the initial size of
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| 22 | the TCP send window, and lastly the initial size of the TCP
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| 23 | receive window. Note that specifying zero means fallback to the
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| 24 | default value.
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| 25 | </p>
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| 26 | <p>
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| 27 | Each of these buffers has a default size of 64KB and default MTU
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| 28 | is 1500.
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| 29 | </p>
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| 30 | </body>
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| 31 |
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| 32 | </topic>
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