Subject: UDP retransmission policies

From: Peter Åstrand <[email-masked]>
Date: Wed, 12 Sep 2001 18:42:54 +0200 (CEST)

RFC1831 says:

"It is important to point out that RPC does not try to implement any kind
of reliability and that the application may need to be aware of the type
of transport protocol underneath RPC.  If it knows it is running on top of
a reliable transport such as TCP [6], then most of the work is already
done for it.  On the other hand, if it is running on top of an unreliable
transport such as UDP [7], it must implement its own time-out,
retransmission, and duplicate detection policies as the RPC protocol does
not provide these services."

What policies does NFSv4 use for retransmissions etc? I cannot find this
information in 3010.

-- 
Peter Åstrand                Telephone: +46-13-29 08 61
Cendio Systems               E-mail: [email-masked]
Teknikringen 3
583 30 Linköping

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From: Spencer Shepler <[email-masked]>
Date: Thu, 13 Sep 2001 15:49:44 -0500

> What policies does NFSv4 use for retransmissions etc? I cannot find this

The only statements about transport usage is in section 3.1.

  "The transport used by the RPC service for the NFS version 4 protocol
   MUST provide congestion control comparable to that defined for TCP in
   [RFC2581].  If the operating environment implements TCP, the NFS
   version 4 protocol SHOULD be supported over TCP.  The NFS client and
   server may use other transports if they support congestion control as
   defined above and in those cases a mechanism may be provided to
   override TCP usage in favor of another transport."

As long as the client follows the above, the implementation is allowed
to retransmit its requests as it sees fit.  Most current
implementations of v2/v3 use a simple backoff for retransmits.

-- 

- Spencer -