# How Engineers at Digital Equipment Corp. Saved Ethernet - IEEE Spectrum

<https://spectrum.ieee.org/how-dec-engineers-saved-ethernet>

- Host: [spectrum.ieee.org](https://links.thingelstad.xyz/hosts/spectrum.ieee.org/)
- Saved: April 11, 2024 (2024-04-12T00:18:21Z)
- Record: https://links.thingelstad.xyz/links/59025b125f3c/
- JSON: https://links.thingelstad.xyz/links/59025b125f3c.json

## What Jamie wrote

This is a great story about the creation of the very first Ethernet bridge, or what we now call a switch. I've got five switches in my house right now making sure my Ethernet network runs super fast. I didn’t realize that Ethernet and I are about the same age. 😊

> The next morning he came in with an idea for a learning bridge (also known as a Layer 2 switch or simply a switch). The bridge would connect to two Ethernet LANs. By listening to all traffic on each LAN, the device would learn the MAC addresses of the computers on both Ethernets (remembering which computer was on which Ethernet) and then selectively forward the appropriate packets between the LANs based upon the destination MAC address. The computers on the two networks didn't need to know which path their data would take on the extended LAN; to them, the bridge was invisible.

How amazing that DEC green-lit the project in a day!

> I took our idea to three levels of management, looking for approval to build a prototype of the learning bridge that Mark envisioned. Before the end of the day, we had a green light with the understanding that a product would follow if the prototype was successful.

I remember token ring networks and even remember Ethernet networks that were running on coax connections but I only saw the very end of that generation of technology. Frankly it is amazing how far Ethernet has evolved and innovated over the years.

> To me, Mark saved Ethernet.

Thank you Mark! 💙

## Facts

- Kind: [Page](https://links.thingelstad.xyz/kinds/page/)

## Appears in

- [WT283: Weekly Thing 283 / Betula, Blocky, Tables](https://weekly.thingelstad.com/archive/283/), Notable

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## Elsewhere

- Wayback Machine: https://web.archive.org/web/*/https://spectrum.ieee.org/how-dec-engineers-saved-ethernet