[Discuss] Dev Ops - architecture (local not cloud)

[Bill Bogstad]

On Fri, Dec 13, 2013 at 1:42 PM, Edward Ned Harvey (blu)
<blu at nedharvey.com> wrote:
>> From: discuss-bounces+blu=nedharvey.com at blu.org [mailto:discuss-
>> bounces+blu=nedharvey.com at blu.org] On Behalf Of Kent Borg

>> Something else I long ago observed: Because ethernet degrades gracefully it
>> always operates degraded.
>
> Ethernet does NOT degrade gracefully.  A graceful degradation would be:  You have 11 machines on a network together.  1 is a server, and 10 are clients.  All 10 clients hammer the server, and all 10 of them each get 10% of the bandwidth that the server can sustain.  This is the behavior of other network switching topologies (in particular IB and FC) but it is not the behavior of Ethernet.  Because Ethernet is asynchronous, buffered, store and forward, with flow control packets and collisions...  Sure, the most intelligent switches can eliminate collisions, but flow control is still necessary, buffering is still necessary...  You have network overhead, and congestion leads to degradation of efficiency.  Each of the 10 clients might be getting 5% of the bandwidth, which is an ungraceful degradation.

Ed:  Can you define what you mean by "collision" in the context of an
Ethernet switch where twisted pair wiring is being used?   (i.e. any
of the commonly used *BaseT wiring systems)   The definition I use
makes collisions impossible and therefore irrelevant to virtually any
discussion of Ethernet taking place in this century.

Thanks,
Bill Bogstad