Large-datagram hop-by-hop delivery mechanism

Sean Donelan SEAN at SDG.DRA.COM
Wed Aug 4 19:54:27 UTC 1999

mark at vielle.datasys.NET (Mark R. Lindsey) writes:
>I am seeking a mechanism for reliable delivery of large blobs through a
>network of occasionally-connected hosts that can forward the blobs using
>available transport protocols.

The phrase "reliable delivery" throws a kink in things.  The Inter-Library
Loan protocol does this for some definition of "reliable."  It is also
amazingly complex and obtuse because it tries to deal with every possibility.
And most people won't like it because it was originally an OSI protocol.

A much simplier solution is to use "e-mail" as the transport layer and to
encapsulate a simple method of detecting missing and duplicate messages
(e.g. a message serial number).  Your application will need to have some
method of signaling when a message needs to be retransmitted.  A simple
return-receipt is usually not sufficient.  I have seen several applications
which did this, but I don't recall any general purpose standard or RFC.

E-mail has a long history, and gateways exist for almost every network
protocol in existance, including most store-and-forward protocols (BITNET,
UUCP, FIDONET, X.25, DECNET, etc).  The MIME folks did a great job coming
up with a way to encapsulate almost anything in a mail message.  The trick
is decapsulating it :-)
Sean Donelan, Data Research Associates, Inc, St. Louis, MO
  Affiliation given for identification not representation

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