Les switchs audiophiles + ponts optiques

[bbill]

(04-03-2025, 03:13 PM)Bosstime a écrit : Le câble c1 est juste incroyable
Entre les 2 switchs bien meilleur que n’importe sfp/fibre et rj45

oui et voici l'explication technique sur la supériorité d'un "Direct Attach Cable" par rapport à de la fibre optique 
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"The ethernet cabling system that we use in our homes is designed to transport large amounts of data at high speeds over an as economical as possible cabling system. For this to work, block coding and error correction enable data to pass through a cheap (economical) cable and connector system without error. The block encoding requires reading the data block into the transmitter, running a mathematical function on the data, and sending the encoded data over the link. The opposite happens at the receiving end, and error correction is applied.

To provide an indication of the processing overhead, this is standardized to take 2.6 microseconds, where the actual data transfer latency is 0.1 microseconds for fiber and 0.3 microseconds for copper (or times 8.6 for copper and times 26 for fiber). But more important is the increase in power consumption which is between 5 and 25 times higher for RJ45 over SFP (for EACH port).

At first glance, SFP fiber appears to be the ideal solution. Unfortunately, it is not as straightforward as an SFP fiber module, which converts an electrical signal into an optical signal and uses a substantial amount of power. A single fiber SFP module consumes more power than our entire switch design, and the additional noise this generates is multiple times higher than that of the switch itself.

Inside the system, there is an accumulation of several types of noise:
Processing noise
Noise generated by power consumption (and associated heat)
Interface noise
We have managed to achieve the absolute lowest possible noise by minimizing these 3 by designing a Network Card and Switch by producing the lowest possible noise, consuming the lowest possible power, and with the least possible processing overhead around using a so-called DAC SFP cable between Network card and Switch."
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il y a donc plusieurs explications...
- le pourquoi de l'intérêt du Dac "Direct Attach Cable" passif (cf câble C1 de Melco ou équivalents IT)
- une explication du pourquoi les modules SFP ne donnent pas tous d'aussi bons résultats
- des raisons pour lesquelles un "pont optique" n'est pas toujours la meilleure solution
- etc... tant qu'à dépenser de l'argent pour un switch, autant le connecter efficacement !