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From: jpn@teddy.UUCP (John P. Nelson)
Newsgroups: net.unix-wizards,net.wanted.sources
Subject: Need reliable datagrams
Message-ID: <3189@teddy.UUCP>
Date: Tue, 16-Sep-86 13:18:36 EDT
Article-I.D.: teddy.3189
Posted: Tue Sep 16 13:18:36 1986
Date-Received: Tue, 16-Sep-86 21:32:54 EDT
Organization: GenRad, Inc., Concord, Mass.
Lines: 27
Keywords: help sockets BSD4.2
Xref: mnetor net.unix-wizards:7892 net.wanted.sources:2284

I have an application that needs to reliably send packets of data
around among several tasks in a system.

I have tried using bidirectional SOCK_STREAM type sockets, but that
serializes my data (it removes the packet boundaries) and, besides, I
run out of descriptors because each socket must be CONNECTed to another
socket on the other end (and each task needs two channels, one for
normal data, and one for breakthru data).

I have also tried using SOCK_DGRAM sockets:  The interface is fine,
but under high load conditions, I lose as many as 20% of my packets!!

My SUN manual lists a SOCK_SEQPACKET protocol as being "planned but
not implemented"; this looks like just what I need.  Too bad.

Has anyone solved this problem?  If I can't get a good UNIX solution,
I'll have to implement my own reliable delivery protocol at task level
(I'm not much of a kernel hacker) - and I'd really HATE to have to do that!
We have all kinds of source licences here:  BSD4.2, BSD4.3, ULTRIX 1.2,
and SUN 3.0.  Any kind of pointers would be appreciated.

  John P. Nelson
  GenRad  M.S. 6
  Concord, MA 01742

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