Jumbo frames and Oracle Net - non-standard MTU sizes can cause clients to hang

See the following documents for a description of this behavior:

Remote Oracle Net connections hang at Authentication point or end with ORA-3135 (Doc ID 1302367.1)

Query on "bigtable" from remote Client hangs (certain queries or fields) (Doc ID 2104257.1)

Occasionally, we use a lower SDU to confirm and/or resolve these issues with large packets.

For example, setting this SQLNET.ORA file parameter at the client that is hanging during authentication might allow the connection to succeed:

DEFAULT_SDU_SIZE=512
or any value lower than 1500:

DEFAULT_SDU_SIZE=1024

This is really not a good solution but rather a test to confirm that the problem is with packet size.