Standards
The published figure, and what it stops short of
Almost every number on a networking or storage box comes from a document somebody else wrote: a channel width, a pair count, a power type, a bus generation. Those documents are precise, and they are precise about narrower things than the packaging suggests. One page per standard, in four parts — what the body that publishes it actually defines, what that definition stops short of promising, what it is written to work alongside, and where on this site it shows up.
Wireless
The IEEE amendments behind the generation names, and the band each one is allowed to use where you live.
Cabling & link speeds
What a cable category is tested to, what a BASE-T link rate needs underneath it, and how far each one reaches.
- Category 6 (Class E) A grade that belongs to the whole link, not to the jacket it is printed on
- Category 6A (Class EA) The category that specifies what the neighbouring cable is doing
- Category 8 (Class I and Class II) The highest category, over the shortest channel in the series
- 1000BASE-T (IEEE 802.3ab) A signalling rate on the wire, and four pairs that all have to be intact
- 2.5GBASE-T (IEEE 802.3bz) A rate designed around the cable already in the wall
- 10GBASE-T (IEEE 802.3an) The copper rate whose cabling grade and heat are both part of the decision
Power over the cable
The three power types a switch or an injector can name, and the gap between what leaves the port and what arrives.
- IEEE 802.3af — Power over Ethernet, Type 1 Two published wattages, and the cable is the difference between them
- IEEE 802.3at — Power over Ethernet Plus, Type 2 The higher allowance is granted by a negotiation, never assumed
- IEEE 802.3bt — four-pair Power over Ethernet, Types 3 and 4 Power on all four pairs, and a switch budget that becomes the real limit
Storage interfaces
The bus a drive speaks and the card size it is cut to — two separate facts that a product name mixes together.