How engineers at Digital Equipment Corp. saved Ethernet
Engineers at Digital Equipment Corporation are credited with “saving” Ethernet by introducing bridges and the spanning tree protocol, which made it practical to link multiple LAN segments without causing catastrophic loops. Commenters reflect on how this enabled simple, extensible networking for non-experts, trace the evolution from coax and shared hubs to switched twisted-pair and faster standards, and note how incremental improvements—rather than clean-slate designs—drove Ethernet’s dominance while alternative technologies and standards faded away.
Spanning Tree Protocol and Ethernet’s “Magic”
- Several commenters praise spanning tree for making Ethernet robust for non-experts, enabling ad‑hoc “extension-cord-style” cabling without physical disaster.
- Others note that STP seems magical at first but becomes straightforward once you see it as building an acyclic graph; one comment walks through a simple loop-detection example.
- Optimizing STP reconvergence is considered hard and “magical” even by technically literate participants.
Failures, Fire, and Power Strips
- Multiple anecdotes involve equipment “magic smoke”: blown capacitors from bad power and brownouts; lightning damage; misused passive PoE.
- A recurring theme is people misusing power strips: plugging a strip into itself, or yanking cords instead of using power buttons, sometimes destroying expensive AV gear.
- There’s debate over whether outlets in US/Europe typically have switches and how people actually power devices off.
Newer Layer‑2 Protocols (SPB, TRILL, EVPN)
- One commenter claims 802.1aq Shortest Path Bridging is a more robust, secure replacement for STP and criticizes how long it took to appear.
- A reply counters that SPB is effectively a “dead letter” standard; operators that would need it tend to use BGP EVPN or other L3 solutions instead.
- TRILL is mentioned as an earlier IETF alternative; IEEE’s later SPB decision is framed as a course correction, but both are said to have limited real-world uptake.
Incremental vs. Revolutionary Innovation
- A parallel is drawn between Ethernet bridges and a philosophy of small, local, incremental improvements leading to big wins.
- Another commenter pushes back, arguing network-layer bridges were a qualitatively new device, not a small tweak.
Ethernet Speed Evolution (10 → 100 → 1000 Mbps and Beyond)
- Several comments explain the long life of 10 Mbps: it was “good enough” relative to small disks, modems, and printers, and faster gear was costly.
- The 10→100 jump required new cabling (Cat 3→Cat 5, plus coax phase-out), making upgrades expensive and slow.
- The 100→1000 jump was faster because it could reuse existing Cat 5 and cheaper PHYs.
- Some note that consumer gear still mostly tops out at 1 Gbps despite affordable 10G-capable components; others argue 1 Gbps is still overkill for most.
Switches, Segments, and Operational Pain
- Early switches did not immediately mean one port per host; they often fronted shared coax segments.
- Over time, as costs fell, networks moved from shared media → hubs → per-host switched ports for reliability and performance.
- Older coax-based Ethernet is remembered as fragile: a bad terminator or user tampering could take down entire floors, making modern switched topologies a welcome tradeoff.
Historical and Practical Nostalgia
- Commenters reminisce about DEC hardware (e.g., Tulip NICs), early SynOptics/3Com gear, and the rapid shift from coax to twisted pair.
- There are memories of juggling DOS network drivers and memory extenders to run multiple protocols, and of early hubs saturating under modest traffic.