Solaris 10 maximum TCP connections

We have quite a few servers whose applications rely on very fast TCP connections. Thousands of ports are open and closed every minute all internally. Although nothing like a large scale website it still is something to deal with. Our Solaris 10 servers came with 128 connections max per port. An issue we saw with when an otherwise quiet server had an increased amount of traffic to it connections were failing. The server hit it's maximum number of connections per port (128 for us) and wouldn't receive anymore until a port freed up. Unfortunately the server CPU and memory usage hit the roof and slowed down the OS and any running applications. So when the application on the client side told the server to close the connection, the server asked the application holding the port open if it can close it but under load the application was unable to respond. The server slowed down to a halt and well production chaos!

So to alleviate this we increase the maximum connection amount to 4192 which gave us plenty of room for now:

ndd -set /dev/tcp tcp_conn_req_max_q 4192