[ih] Internet History - from Community to Big Tech?

[Joe Touch]

On Mar 31, 2019, at 7:31 PM, Richard Bennett <richard at bennett.com> wrote:
> 
> One of the funniest bits of history about Ethernet is an interview where Bob Metcalfe said he and Boggs designed around passive cable because they felt a hub or switch would be a bottleneck.

Switches and shared media both experience the bottleneck that prevents two sources from talking to one sink at the same time. 

Shared media manage this bottleneck this via effects that happen at the physical layer. Switches enforce this through buffering and scheduling.

Shared media experience other bottlenecks that switches do not. I.e., in some ways, a switch emulates a wire, but it also it allows communication exchanges that a wire cannot. So the reality is opposite their intuition, given ‘wire speed’ devices...


> Given that the switch is an electronic device that moves bits between other electronic devices this never made much sense. Can a NIC generate traffic faster than than a switch can relay it?

It’s possible to generate data faster than it can be received, but that wouldn’t be particularly useful. So assuming NICs that do both at the same speeds, it’s impossible to generate data faster than something can switch it - at a minimum, the data could be switched through a multiple stages of NIC/computers (e.g., a Clos network).

> And as we see with switching fabrics, the wire has been the bottleneck all along. 

Well, to paraphrase Doc Brown, "where we’re going, we don’t need wires…” (if we use optics).

Joe