Where to add SDU and TDU values in scan listener file in cluster database ?

I have a RAC database with scan listener. I am trying to use non-default values for SDU and TDU in tnsnames and listener files.

My listener, tnsnames and sqlnet files are same in both Grid and Oracle Homes on all the DB nodes.

This is how my tnsnames looks like:

xxx =

(DESCRIPTION =

   (SDU = 8192)

   (TDU = 8192)

   (ADDRESS = (PROTOCOL = TCP)(HOST = yyy)(PORT = 1521))

   (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = zzz)))

This is how my sqlnet looks like:

NAMES.DIRECTORY_PATH= (TNSNAMES, EZCONNECT)

SQLNET.EXPIRE_TIME=10

This is how my listener file in Grid Home looks like. I don't have listener.ora file Oracle Home. This is how I got it after Oracle did Exadata install. No changes made to listener file.