TCP and UDP Network Configuration

This section describes how to optimize network configuration parameters for default TCP and UDP send and receive socket buffers sizes to improve VoIP performance and reliability under extreme load.

At startup a number of network configuration parameters are set by the AIX kernel. These parameters include the default TCP and UDP send and receive socket buffers sizes. These buffers are used to store messages that have been sent or received from the network, if these buffers become full, then this can result in failures sending TCP/UDP messages, TCP/UDP messages being lost with messages having to be resent. For the Blueworx Voice Response VoIP feature this could result in performance and reliability issues under extreme load. It is therefore recommend that the default values for these parameters are increased. By default the four parameters have the following values:

udp_sendspace = 9k
udp_recvspace = 42k
tcp_sendspace = 16k
tcp_recvspace = 16k
The no (network options) command can be used to view and change default network attributes. To view these values, as root, simply type 
no -o parameter
where parameter can be one of the following:
udp_sendspace
To review the udp send buffer size in bytes.

For example, no -o udp_sendspace returns udp_sendspace=9216.

udp_recvspace
To review the udp receive buffer size in bytes.

For example, no -o udp_recvspace returns udp_recvspace=9216.

To reset these values, simply type 
no -o parameter=newValue
Where parameter refers to the network parameter you wish to change, and newValue is the new value to which you want to set it. For example, to set the tcp_sendspace to be 64k, type the following: 
no -o tcp_sendspace=64000
The confirmation message Setting tcp_sendspace to 64000 is displayed.