The Ultimate questions on Linux, the Universe, and Everything

There have been efforts a few years ago in bringing 10 Gbit/s network speeds to PC motherboards. It has also been used in servers, but mostly using fiber cable. It is only recently when the standard has evolved to be usable with regular twisted pair copper cable. With CAT6a cable you could in theory reach 100 m using 10GBASE-T. Due to the high requirements of 10 Gbit ethernet, it is often not possible to communicate over longer links due to not spec compliant cable, or when using much more common CAT5e cable. What happens then is that the network link speed is lowered from 10 Gbit/s to 1 GBit/s. Recently a new standard has been evolving to lower the implications of this problem. New speeds of 5 Gbit/s and 2.5 Gbit/s have been introduced in a new standard IEEE 802.3bz and then later in practice as the NBASE-T alliance. With IEEE 802.3bz, a speed of 5 GBit/s can be used with up to 100 m CAT5e copper cable. What this means is that when your 10 Gbit/s link doesn't manage to k...

I have a small cabinet for modem, router, network switch and 8-port patch panel. I've managed to squeeze in a small UPS as well. When I finally got DOCSIS 100/20 Mbit Internet, the cable modem was so big that I had to make some changes to the cabinet. It is good to have an UPS for the equipment. Internet usually works during short power outages and the equipment is not damaged by hard reboots. It also protects somewhat against voltage spikes. So when all of the equipment runs on 12 V it got me thinking. Why do I need an UPS that converts 230 V AC into 12 V DC (for the battery) and then to 230 V DC again, and then at least three small adapters to convert it separately to 12 V DC again? Instead I could replace it with one larger 12 V DC power supply combined with a battery. I found a 12 V UPS, a Mean Well AD-55A . It outputs 4 A at 13.8 V DC and a small battery can be attached (charge 13.4 V, 0 - 0.23 A). Output voltage is adjustable between 12 - 14.5V. It has of course to...