# 10BASE2
**10BASE2** is a variant of Ethernet that carries 10 Mbit/s signals over thin 50-ohm coaxial cable, with stations daisy-chained along a shared bus. It is known as thin Ethernet, thinnet, or cheapernet, and it was standardized in the late 1980s as a cheaper, lighter alternative to the original 10BASE5 thick-coaxial system.[1](https://www-users.york.ac.uk/~dajp1/Docs/Old_Stuff/GSW_Ethernet.pdf) • [2](https://web.cs.wpi.edu/~rek/Nets2/D11/Ethernet_D11.pdf)
| Key fact | Detail |
|---|---|
| Speed and medium | 10 Mbit/s baseband Ethernet over thin RG-58 coaxial cable[3](https://goughlui.com/2015/11/01/tech-flashback-ethernet-10mbits-network-interface-card-collection/) • [4](https://s2.smu.edu/~nair/ftp/senior_design/scada/Practical_SCADA_for_Industry.pdf) |
| Cable type | RG-58 A/U or C/U with 50 ohm characteristic impedance[4](https://s2.smu.edu/~nair/ftp/senior_design/scada/Practical_SCADA_for_Industry.pdf) |
| Segment limits | Maximum segment length 185 m, maximum 30 nodes per segment[4](https://s2.smu.edu/~nair/ftp/senior_design/scada/Practical_SCADA_for_Industry.pdf) • [5](https://www.tiplord.com/networking/thin.htm) |
| Connections | BNC T-connectors at each station; 50-ohm BNC terminators at both cable ends[6](https://www.electronicsguide.net/foundations-and-theory/history/information-age-dawn-1985-1995/internet-and-networking-revolution/) • [5](https://www.tiplord.com/networking/thin.htm) |
| Purpose | Developed after 10BASE5 specifically to reduce installation costs[4](https://s2.smu.edu/~nair/ftp/senior_design/scada/Practical_SCADA_for_Industry.pdf) |
| Standardization | IEEE 802.3 variant dated 1985 in Ethernet evolution charts; described as a late-1980s and early-1990s standardization[2](https://web.cs.wpi.edu/~rek/Nets2/D11/Ethernet_D11.pdf) • [1](https://www-users.york.ac.uk/~dajp1/Docs/Old_Stuff/GSW_Ethernet.pdf) |
| Decline | Displaced by 10BASE-T twisted-pair Ethernet, first implemented with RJ45 connectors in 1990[7](https://www.tomshardware.com/networking/the-ethernet-spec-was-first-drafted-on-this-day-in-1980-dec-intel-and-xerox-defined-the-standard-several-years-before-the-internet-existed) |
## Origin and purpose
The original Ethernet media system was 10BASE5, specified in the DIX standard of 1980 by [Digital Equipment Corporation](https://www.edgepedia.org/digital-equipment-corporation), Intel, and Xerox. It used thick, stiff RG-8 style coaxial cable that required special vampire taps and expensive equipment, but offered low loss and a 500 m range.[8](https://www.oreilly.com/library/view/ethernet-the-definitive/1565926609/apb.html) • [3](https://goughlui.com/2015/11/01/tech-flashback-ethernet-10mbits-network-interface-card-collection/)
In response to customer demand for a cheaper system, 10BASE2 was standardized in the late 1980s and early 1990s era of Ethernet development, using a thinner coaxial cable that linked all the computers in a chain.[1](https://www-users.york.ac.uk/~dajp1/Docs/Old_Stuff/GSW_Ethernet.pdf) Ethernet evolution charts date the 10BASE2 "Cheapernet" variant to 1985.[2](https://web.cs.wpi.edu/~rek/Nets2/D11/Ethernet_D11.pdf) The design goal was stated plainly in contemporary descriptions: thin coaxial Ethernet was developed after 10BASE5 and designed to reduce the costs of installation.[4](https://s2.smu.edu/~nair/ftp/senior_design/scada/Practical_SCADA_for_Industry.pdf)
## Physical wiring
A 10BASE2 segment is a single run of flexible RG-58 coaxial cable, type A/U or C/U, with a 50 ohm characteristic impedance.[4](https://s2.smu.edu/~nair/ftp/senior_design/scada/Practical_SCADA_for_Industry.pdf) Each station attaches through a BNC T-connector, so the cable passes from one network interface card to the next along the bus. Both ends of the segment must be closed with 50-ohm BNC terminators; a missing or wrong terminator brings the whole segment down.[6](https://www.electronicsguide.net/foundations-and-theory/history/information-age-dawn-1985-1995/internet-and-networking-revolution/) • [5](https://www.tiplord.com/networking/thin.htm)
The limits per segment are a maximum length of 185 meters and a maximum of 30 nodes.[4](https://s2.smu.edu/~nair/ftp/senior_design/scada/Practical_SCADA_for_Industry.pdf) • [5](https://www.tiplord.com/networking/thin.htm) The name itself encodes the speed and approximate reach: 10 for 10 Mbit/s, BASE for baseband signaling, and 2 for roughly 200 meters (the actual limit, 185 m, falls just short of that round figure).[4](https://s2.smu.edu/~nair/ftp/senior_design/scada/Practical_SCADA_for_Industry.pdf)
## Building larger networks
Segments can be joined with repeaters, which regenerate the signal and extend the network beyond a single 185 m run; multi-port repeaters could connect four or even eight cable segments.[5](https://www.tiplord.com/networking/thin.htm) More than one repeater is allowed, but the total topology is bounded by the 5-4-3 rule: between any two stations there may be at most five segments, four repeaters, and only three of those segments populated with stations. In this counting a 10BASE-T hub behaves like a repeater, and a 10BASE-T link counts as a cable with just two systems on it.[9](https://www.rigacci.org/docs/biblio/online/netrule/netrule.htm) The 5-4-3 restriction exists because the shared-medium collision domain of a 10 Mbit/s Ethernet is formally defined by a one-way propagation window of 25.6 microseconds.[10](https://www.sciencedirect.com/topics/computer-science/transparent-bridging)
## Operation as a shared medium
Like 10BASE5, 10BASE2 was a shared-medium system: all stations on a segment shared the 10 Mbit/s channel and arbitrated access by the Ethernet collision protocol.[3](https://goughlui.com/2015/11/01/tech-flashback-ethernet-10mbits-network-interface-card-collection/) This bus architecture had practical consequences for reliability. Because the cable run is continuous, a single break, a loose T-connector, or a removed terminator disabled the entire segment, and locating the fault meant tracing the coax through the office.
## Decline
Through the late 1980s and early 1990s 10BASE2 was extensively used, particularly where cost mattered.[1](https://www-users.york.ac.uk/~dajp1/Docs/Old_Stuff/GSW_Ethernet.pdf) Its replacement came from twisted pair. The first RJ45 implementation appeared in 1990 alongside the introduction of 10BASE-T twisted-pair cabling, still at 10 Mbit/s.[7](https://www.tomshardware.com/networking/the-ethernet-spec-was-first-drafted-on-this-day-in-1980-dec-intel-and-xerox-defined-the-standard-several-years-before-the-internet-existed) Structured wiring with a central hub removed the shared-bus failure mode, since a disconnected station no longer affected its neighbors, and falling adapter prices, driven by single-chip controllers and vendor competition, brought Ethernet cards from several hundred dollars in the late 1980s to under one hundred dollars for a 10BASE-T ISA card by the mid-1990s.[6](https://www.electronicsguide.net/foundations-and-theory/history/information-age-dawn-1985-1995/internet-and-networking-revolution/)
## References
1. [Communication Networks, University of York course notes (GSW Ethernet)](https://www-users.york.ac.uk/~dajp1/Docs/Old_Stuff/GSW_Ethernet.pdf)
2. [Ethernet Evolution, Advanced Computer Networks, WPI](https://web.cs.wpi.edu/~rek/Nets2/D11/Ethernet_D11.pdf)
3. [Tech Flashback: Ethernet (10Mbit/s) NIC Collection, Gough's Tech Zone](https://goughlui.com/2015/11/01/tech-flashback-ethernet-10mbits-network-interface-card-collection/)
4. [Practical SCADA for Industry, Southern Methodist University](https://s2.smu.edu/~nair/ftp/senior_design/scada/Practical_SCADA_for_Industry.pdf)
5. [Thin Ethernet (10BASE2), Tiplord](https://www.tiplord.com/networking/thin.htm)
6. [Internet and Networking Revolution, Electronics Guide](https://www.electronicsguide.net/foundations-and-theory/history/information-age-dawn-1985-1995/internet-and-networking-revolution/)
7. [The Ethernet spec was first drafted on this day in 1980, Tom's Hardware](https://www.tomshardware.com/networking/the-ethernet-spec-was-first-drafted-on-this-day-in-1980-dec-intel-and-xerox-defined-the-standard-several-years-before-the-internet-existed)
8. [Thick and Thin Coaxial Media Systems, Ethernet: The Definitive Guide, O'Reilly](https://www.oreilly.com/library/view/ethernet-the-definitive/1565926609/apb.html)
9. [Large Networks: 5-4-3 Rule, Rigacci](https://www.rigacci.org/docs/biblio/online/netrule/netrule.htm)
10. [Transparent Bridging, ScienceDirect Topics](https://www.sciencedirect.com/topics/computer-science/transparent-bridging)
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*Topic: Encyclopedia › Technology and the built world › Computing and digital systems › Networks and security › Ethernet › Ethernet standards and speeds › Classic Ethernet (pre-10 Mbps)*
*Initially written Sep 17, 2026 · Reviewed: Sep 30, 2026; Oct 15, 2026 · Edited: Oct 15, 2026; Oct 25, 2026 · Last review: Oct 15, 2026*
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License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license