[ih] The origin of variable length packets

[Stephen Suryaputra]

Hi,

I¹m reading Paul Baran¹s paper:

P. Baran, "On Distributed Communications Networks," Communications Systems,
IEEE Transactions on, vol. 12, pp. 1-9, 1964.

And saw something interesting. The message block (aka "packet") described in
this paper is a fixed size of 128 bytes. And there is even a mention saying
that the fixed size enables high speed implementation of switches.

Out of curiosity, I tried to trace when the packet becomes variable length.
But, no success. This paper indicates that there is a maximum packet size,
so it's already variable by 1974:

V. Cerf and R. Kahn, "A Protocol for Packet Network Intercommunication,"
Communications, IEEE Transactions on, vol. 22, pp. 637-648, 1974.

Any pointer or reasons why the packet becomes variable length later on? A
reference would be really appreciated.

Thanks,

Stephen.