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<indexterm> |
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<indexterm> |
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<primary>TCP Bandwidth Delay Product Limiting</primary> |
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<primary>TCP Bandwidth Delay Product Limiting</primary> |
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<secondary><varname>net.inet.tcp.inflight_enable</varname></secondary> |
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<secondary><varname>net.inet.tcp.inflight.enable</varname></secondary> |
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</indexterm> |
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</indexterm> |
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<para>The TCP Bandwidth Delay Product Limiting is similar to |
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<para>The TCP Bandwidth Delay Product Limiting is similar to |
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TCP/Vegas in NetBSD. It can be |
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TCP/Vegas in NetBSD. It can be |
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enabled by setting <varname>net.inet.tcp.inflight_enable</varname> |
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enabled by setting <varname>net.inet.tcp.inflight.enable</varname> |
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sysctl variable to <literal>1</literal>. The system will attempt |
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sysctl variable to <literal>1</literal>. The system will attempt |
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to calculate the bandwidth delay product for each connection and |
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to calculate the bandwidth delay product for each connection and |
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limit the amount of data queued to the network to just the amount |
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limit the amount of data queued to the network to just the amount |
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Lines 2187-2195
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with a high bandwidth delay product), especially if you are also |
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with a high bandwidth delay product), especially if you are also |
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using window scaling or have configured a large send window. If |
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using window scaling or have configured a large send window. If |
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you enable this option, you should also be sure to set |
2189 |
you enable this option, you should also be sure to set |
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<varname>net.inet.tcp.inflight_debug</varname> to |
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<varname>net.inet.tcp.inflight.debug</varname> to |
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<literal>0</literal> (disable debugging), and for production use |
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<literal>0</literal> (disable debugging), and for production use |
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setting <varname>net.inet.tcp.inflight_min</varname> to at least |
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setting <varname>net.inet.tcp.inflight.min</varname> to at least |
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<literal>6144</literal> may be beneficial. However, note that |
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<literal>6144</literal> may be beneficial. However, note that |
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setting high minimums may effectively disable bandwidth limiting |
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setting high minimums may effectively disable bandwidth limiting |
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depending on the link. The limiting feature reduces the amount of |
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depending on the link. The limiting feature reduces the amount of |
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Lines 2202-2208
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/ server side). It has no effect on data reception (downloading). |
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/ server side). It has no effect on data reception (downloading). |
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</para> |
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</para> |
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<para>Adjusting <varname>net.inet.tcp.inflight_stab</varname> is |
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<para>Adjusting <varname>net.inet.tcp.inflight.stab</varname> is |
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<emphasis>not</emphasis> recommended. This parameter defaults to |
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<emphasis>not</emphasis> recommended. This parameter defaults to |
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20, representing 2 maximal packets added to the bandwidth delay |
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20, representing 2 maximal packets added to the bandwidth delay |
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product window calculation. The additional window is required to |
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product window calculation. The additional window is required to |
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Lines 2211-2217
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links (though still much lower than you would get without the |
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links (though still much lower than you would get without the |
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inflight algorithm). In such cases, you may wish to try reducing |
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inflight algorithm). In such cases, you may wish to try reducing |
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this parameter to 15, 10, or 5; and may also have to reduce |
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this parameter to 15, 10, or 5; and may also have to reduce |
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<varname>net.inet.tcp.inflight_min</varname> (for example, to |
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<varname>net.inet.tcp.inflight.min</varname> (for example, to |
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3500) to get the desired effect. Reducing these parameters |
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3500) to get the desired effect. Reducing these parameters |
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should be done as a last resort only.</para> |
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should be done as a last resort only.</para> |
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</sect3> |
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</sect3> |