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Created attachment 612794 [details]
wireshark packet capture data

Description of problem:

On normal activity, the NFS client hangs and can't re-establish communication with our NFS server (Netapp filer FAS2050).
the MNT operation is successful. The client fails on ‘fsinfo’ call. It attempts to reuse existing socket to connect to 2049 port on NFS server. It fails there. As a result it even doesn’t try to establish TCP connection with the NFS server (to port 2049).

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

Name        : nfs-utils
Arch        : x86_64
Epoch       : 1
Version     : 1.2.3
Release     : 26.el6

How reproducible:

Not reproducible. The problem is totally Aleatory.

Steps to Reproduce:
1.
2.
3.
  
Actual results:


Expected results:


Additional info:

Created attachment 612795 [details]
RPC debug file

NFS uses a random port (from 665 to 1023) to communicate between the client and the server.
There was a very old ACL rule implemented on the switch between the server subnet and the client subnet
This rule filtered tcp port 707
The rule has been removed, no crash since this ACL modification.

Sounds like we can close this as not a bug. Please reopen if I misunderstand. 

thanks!