How can I tell whether a TCP/IP connection is eligible for Outbound Right Sizing (ORS) and, if eligible, whether ORS is being performed?

Outbound Right Sizing (ORS) is a z/OS Communications Server optimization that improves overall performance for certain high latency streaming workloads. ORS allows the TCP send buffer size for a connection to expand because of network conditions. ORS is enabled for connections that meet the followi

• The round trip time (RTT) for network latency is 2 ms or longer.

• The initial receive buffer size is at least 64 KB.

To determine whether the connection is eligible for ORS optimization, and if the connection is eligible, whether the ORS optimization is performed, issue the Netstat ALL/-A command. Then examine the TcpPrf2 field value for the connection in the Netstat ALL/-A report output:

TcpPrf2

A 1-byte hexadecimal TCP performance flag that can have any of the following values:

40 .1.. .... If outbound right sizing (ORS) is active for this connection, the stack expanded the send buffer beyond its original size.

20 ..1. .... Indicates that this connection is eligible for ORS optimization support.

10 ...1 .... Indicates that ORS is active for this connection so that the stack automatically tunes the send buffer size. The SendBufferSize field shows the current size of the send buffer for this connection.