[ih] The origin of variable length packets

[casner at acm.org (Stephen Casner)]

On Tue, 1 Mar 2011, dave.walden.family at gmail.com wrote:

> The early voice experiments over the ARPANET required the "raw
> packets" capability of the IMPs to be enabled which forgot about
> reliable (more or less), ordered transmission of messages of packets
> across the net ( which slowed up speech too much) and delivered
> single packets in whatever order they got to the destination IMP.
> At least this is how I remember it. John Makhoul would remember
> more.

That description is accurate.  Much of the time the packet voice
systems sent packets of constant size, although the size was
adjustable by varying the amount of time each was to hold.  (I
remember running some experiments varying the packet size to see if
there was an optimum.)  Later a variable-rate encoding algorithm was
developed, so then the packet size would have varied even at a
constant packet rate.

> (Unfortunately Jim Forgie died recently.)

Sorry to hear that.  He was a good guy.

                                                        -- Steve