Tunable network parameters on Linux

Article:HOWTO64299  |  Created: 2011-12-29  |  Updated: 2012-01-12  |  Article URL http://www.symantec.com/docs/HOWTO64299
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Tunable network parameters on Linux

You can tune the following Linux network parameters to resolve some or all of your network issues:

net.core.rmem_max

Specifies the maximum TCP receive window size.

net.core.wmem_max

Specifies the maximum TCP transmit window size.

net.ipv4.tcp_rmem

Specifies the minimum, default, and maximum TCP receive window size.

net.ipv4.tcp_wmem

Specifies the minimum, default, and maximum TCP transmit window size.

net.ipv4.tcp_window_scaling

Enables window scaling, as defined in RFC1323.

net.ipv4.tcp_timestamps

Enables timestamps, as defined in RFC1323.

net.ipv4.tcp_sack

Enables select acknowledgments (SACKS).

net.ipv4.tcp_no_metrics_save

Disables the caching of metrics on closing connections.

net.ipv4.tcp_moderate_rcvbuf

Enables TCP receive buffer auto-tuning. With receive buffer auto-tuning , TCP attempts to set the size of the buffer to match the size required by the path for full throughput. The resulting size will not be greater than the maximum specified by the net.ipv4.tcp_rmem parameter. This is enabled by default.

net.core.netdev_max_backlog

Specifies the maximum number of packets that can be queued on the input side. This queue is used when the interface receives packets faster than kernel can process them. The default value is 1000.

net.ipv4.tcp_max_syn_backlog

Specifies the maximum number of remembered connection requests that have not received an acknowledgment from connecting client. The default value is 1024 for systems with more than 128 MB of memory, and 128 for low memory machines. If server becomes overloaded with requests, then increase this number.

Ethernet interface txqueuelen

Specifies the length of the Ethernet interface transmit queue.

You can tune these parameters by using the sysctl command.

See the sysctl(8) manual page.

See Tuning the operating system network parameters


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