Description of problem:

When attempting to mount and umount a large number (200+) nfs files systems via 
the automounter using the tcp protocol, after approximately 150 sucessful 
mounts and umounts, all subsequent mount attempt fail with the following 
messages:

 RPC: Authentication error; why = Client credential too weak

Note that this occurs when running as root.

The following script can be used to reproduce the error:
count=0
while read mp
do
   cd /sopt/$mp
   pwd
   cd /
   umount /sopt/$mp
   count=`expr $count + 1`
   echo $count
done< /tmp/mp.list

In the example above, /sopt is automounter mount point and the file mp.list is 
list of approximately 800+ potential mount points (essentially all available 
maps in our nis map "auto.sopt" (below).

Additionally, the problem does not occur when using the udp protocol.

The file auto.master contains the following:
/sopt   yp:auto.sopt -proto=tcp,rsize=32768,wsize=32768



Version-Release number of selected component (if applicable):

RHEL 3 WS Update 6
kernel-2.4.21-37.ELsmp
autofs-4.1.3-154


How reproducible:
See Description

Steps to Reproduce:
1. Attempt to mount and immediately umount 200+ file systems in succesion via 
the autmounter using the tcp protocal for nfs.
2.
3.
  
Actual results:

After about ~150 successful mounts and umounts, all subsequent mount attempts 
fail on the automounter mount point for approximately 30 seconds to 1 minute.

The message below appears for each failed mount attempt (with the name of the 
file system that was not able to be mounted):

cd: /sopt/exptools: No such file or directory

The message in /var/log/messages is:
Nov 17 11:06:04 machine1 automount[3285]: mount(nfs): nfs: mount failure  
on /sopt/exptools
Nov 17 11:06:04 machine1 automount[3285]: failed to mount /sopt/exptools
Nov 17 11:06:04 machine1 automount[3291]: >> nfs bindresvport: Address already 
in use
Nov 17 11:06:04 machine1 automount[3305]: >> mount: RPC: Authentication error; 
why = Client credential too weak


Expected results:
Expectation is to be able to successfully mount and umount several hundred file 
systems in succession

Additional info: