Ethernet

"Today, Ethernet is the grand unifying technology that enables communication of multiple forms of content voice, video and data via the Internet and other networks using Internet Protocol (IP). Due to Ethernet's proven low implementation cost, its known reliability, and relative simplicity of installation and maintenance, its popularity has grown to the point that today nearly all traffic on the Internet starts or ends on an Ethernet connection."
"Ethernet consistently demonstrates the most attractive cost/performance ratio of any networking technology, at any operating speed."
"Today, Ethernet arguably carries 99.99 percent of Internet packets, and the performance bar is set at 10 gigabits per second (Gbps), or 10GbE, the standard ratified in 2002."

Ethernet summary
IEEE Name Year cable max segment distance
802.3i 10Base-T 1990 Cat 3 100m
802.3u 100Base-TX Fast Ethernet 1995 Cat 5 100m
802.3u 100Base-FX and -SX Fast Ethernet 1995 2 strands multimode fiber FX: 412m, 2km full duplex. SX: 300m
802.3z 1000BASE-X Gigabit Ethernet 1998 fiber. SX: multimode (short wavelength). LX: singlemode (long wavelength) or multimode SX: 220/500m. LX: singlemode 2km+, multimode 550m
802.3ab 1000Base-T Gigabit Ethernet 1999 Cat 5/5e/6 (all 4 pairs used) 100m
802.3an [-2005]? 10GBASE?? 10GbE (10 gigabit Ethernet) 2003 fiber various...
802.3an 10GBASE-T 10GbE (10 gigabit Ethernet) 2006 Cat 6/6a/7 6: 56m. 6a: 100m
802.3bz 2.5GBASE-T 5GBASE-T 2016 Cat 5e/6/6a
802.3ba bg,bj,bm,cd 40GbE, 100GbE 2010-2018 fiber fiber: ≤80km, twinax:7m, "Cat 8":30m(40GBASE-T)
802.3bs ... TbE (>100GbE) 400GbE 2017 fiber

1000BASE-ZX and LH singlemode reach 70-100 km.

10BaseT was half-duplex, only one station/node transmitting at a time, CSMA/CD, hub as concentrator and active repeater of UTP cables (analogy: party line / conference call). Transmitted frame essentially broadcast to all other nodes.
Full-duplex added with 100Mbps versions eliminates need for CSMA/CD (is disabled), can receive while transmitting thus 200Mbps bandwidth per station, concentrator must be full-duplex capable switch.
Trends: faster, stricter cabling requirements, complex encoding and electronics.

Jumbo 9KB, 16KB frames non-standard? non-interoperable?
Used in SAN and? NAS for greater efficiency.

CSMA/CD: (carrier-sense multiple-access with collision detection). obsolete.
Node wanting to transmit a frame first listens to (shared) medium, if link busy then wait.
until link is unused, then transmit frame, listening for collision
if collision, both transmitters stop, backoff (i.e. wait) for random timeout, then goto start again.
Because each of the two transmitting/colliding nodes wait for different backoff (by randomness), one will timeout before the other and probably be able to get the medium.


PSE: switch. PDs: WAP, security camera, VoIP, smart clock, LED lighting, POS, signage, locks, ...
Midspan injector.
Heat: Smaller cable bundles. Shielded cable.
Active: negotiate with PD using LLDP (or Cisco CDP). Passive: always-on, 24V.

Backbone switches
Campus network