Resolution:

The RV default TCP send/receive buffer size is 128K. There are OS environment variables for the TCP send/receive default buffer size. RV uses the larger of the two values (either its own default value or the value specified in the environment). 

Suppose the TCP max buffer size is high enough.

On Solaris, the environment parameter should be tcp_recv_hiwat AND tcp_xmit_hiwat.  For more detail,  refer to http://docs.oracle.com/cd/E19455-01/816-0607/6m735r5ga/index.html#chapter4-45

Check the following results:

ndd -get /dev/tcp tcp_xmit_hiwat

ndd -get /dev/tcp tcp_recv_hiwat

ndd -get /dev/tcp tcp_cwnd_max

ndd –get /dev/tcp_max_buf

On Linux:

sysctl -p | grep mem   -   This will display the current buffer settings. Save these as you may want to roll-back these changes.

sysctl -w net.core.rmem_max=8388608   -   This sets the maximum OS receive buffer size for all types of connections.

sysctl -w net.core.wmem_max=8388608   -   This sets the maximum OS send buffer size for all types of connections.

sysctl -w net.core.rmem_default=65536     -   This sets the default OS receive buffer size for all types of connections.

sysctl -w net.core.wmem_default=65536   -    This sets the default OS send buffer size for all types of connections.

sysctl -w net.ipv4.tcp_mem='8388608 8388608 8388608'   -  TCP Autotuning setting. "The tcp_mem variable defines how the TCP stack should behave when it comes to memory usage. The first value specified in the tcp_mem variable tells the kernel the low threshold. Below this point, the TCP stack do not bother at all about putting any pressure on the memory usage by different TCP sockets.  The second value tells the kernel at which point to start pressuring memory usage down.  The final value tells the kernel how many memory pages it may use maximally. If this value is reached, TCP streams and packets start getting dropped until we reach a lower memory usage again. This value includes all TCP sockets currently in use."

sysctl -w net.ipv4.tcp_rmem='4096 87380 8388608'   -   TCP Autotuning setting. "The first value tells the kernel the minimum receive buffer for each TCP connection, and this buffer is always allocated to a TCP socket, even under high pressure on the system.  The second value specified tells the kernel the default receive buffer allocated for each TCP socket. This value overrides the /proc/sys/net/core/rmem_default value used by other protocols.  The third and last value specified in this variable specifies the maximum receive buffer that can be allocated for a TCP socket."

sysctl -w net.ipv4.tcp_wmem='4096 65536 8388608'   -   TCP Autotuning setting. "This variable takes 3 different values which holds information on how much TCP sendbuffer memory space each TCP socket has to use. Every TCP socket has this much buffer space to use before the buffer is filled up. Each of the three values are used under different conditions. ... The first value in this variable tells the minimum TCP send buffer space available for a single TCP socket.  The second value in the variable tells us the default buffer space allowed for a single TCP socket to use. ... The third value tells the kernel the maximum TCP send buffer space."

sysctl -w net.ipv4.route.flush=1   -   This will enusre that immediately subsequent connections use these values.