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Computer Networks (CITS3230) - Lecture 11
 
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The NFS Server and Client Relationship

Most operating system vendors believe that each workstation on a LAN is independent and, as a consequence, hosts acting as clients and servers have very different roles to perform when accessing file systems over a network.

  • A server is stateless if the response to a request does not depend in any way on the history of previous requests.
  • Only stateless servers can work correctly over an unreliable communication channel.

The Network File System and the OSI Model

NFS uses a datagram network service, the (unreliable) User Datagram Protocol (UDP/IP). If any datagram is lost or delayed, it may simply be retransmitted by the client without consequence.

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Each remote input/output operation carries all information needed to complete the operation.

e.g. for R/W operations, the file position is sent with each request. The client workstation does not rely on the server maintaining file position.

Computer Networks (CITS3230), Lecture 11, p2, 26th May 2008.