Here's an item of interest that was passed to me from the Level 2 team in
Support:

James Shanks
Tivoli (NetView for UNIX) L3 Support



The  following AIX PTFs have been PE'd:

     AIX 4.2.1 PTF: bos.net.tcp.client 4.2.1.22    (IX84982)
     AIX 4.3.2 PTF: bos.net.tcp.client 4.3.2.4      (IX85539)

  If you get a customer on AIX 4.2.1 or 4.3 with strange socket issues,
e.g. netstat -an shows massive queue backups without an obvious reason,
check the lslpp -ha for one of these filesets.  The AIX 4.2.1 PTF has been
replaced by bos.net.tcp.client 4.2.1.23.  Rejecting the fileset is
currently the only 4.3 solution.  This bug (IX87310) hoses the socket when
large data transfers occur over large MTU interfaces, i.e. loopback.
Problems reported, so far, include nvcorrd(1666)->nvserverd(1665) socket
problems, often masquerading as ruleset problems.