Consideration for setting Parameters for Scan and Node Listeners on RAC, Queuesize, SDU, Ports, etc
TNS listener information held in a listener.ora for releases >= 11.2 on RAC should not be modified. That is the IPC endpoint information for a node listener should not be changed. Global listener parameters can be set in the file, ie it is supported to add tracing parameters and ASO parameters like wallet location, etc.
SDU cannot be set in TCP endpoint for SCAN / Node listeners, but SDU can be changed via the global parameter DEFAULT_SDU_SIZE in the SQLNET.ORA file.
(Set this in the RDBMS oracle home sqlnet.ora file)
Scan listeners are not configured by the standard methods or using *.ora files, but rather built during install and manipulated using via srvctl.
Information on setup is held within Grid Infrastructure(GI). Currently there is no option for adding parameters such as SDU and QUEUESIZE to a listener.
SCAN only supports one address in the TNS connect descriptor and allows only 1 port assigned to it. Default port is 1521, but can be changed if required.
ER 11782958 has been raised to address the current restrictions that are in place around listener parameters on RAC and release 11.2.
Where there is a global parameter, this can be used in place.
As a side note, TCP.QUEUESIZE parameter is now available in 188.8.131.52+ (The patch for TCP.QUEUESIZE can be located on Metalink Note under patch 13777308), which enables SDU/Queuesize. The default is the system-defined maximum value. The defined maximum value for Linux is 128.
Allowable values are any integer value up to the system-defined maximum; e.g., TCP.QUEUESIZE=100