An ethernet frame may carry one of several types of data.

Ethernet was developed at Xerox PARC between 1973 and 1974.[4][5] It was inspired by ALOHAnet, which Robert Metcalfe had studied as part of his PhD dissertation.[6] The idea was first documented in a memo that Metcalfe wrote on May 22, 1973, where he named it after the luminiferous aether once postulated to exist as an "omnipresent, completely-passive medium for the propagation of electromagnetic waves."[4][7][8] In 1975, Xerox filed a patent application listing Metcalfe, David Boggs, Chuck Thacker, and Butler Lampson as inventors.[9] In 1976, after the system was deployed at PARC, Metcalfe and Boggs published a seminal paper.[10][a] Yogen Dalal,[12] Ron Crane, Bob Garner, and Roy Ogus facilitated the upgrade from the original 2.94 Mbit/s protocol to the 10 Mbit/s protocol, which was released to the market in 1980.[13]

Metcalfe left Xerox in June 1979 to form 3Com.[4][14] He convinced Digital Equipment Corporation (DEC), Intel, and Xerox to work together to promote Ethernet as a standard. As part of that process Xerox agreed to relinquish their 'Ethernet' trademark.[15] The first standard was published on September 30, 1980 as "The Ethernet, A Local Area Network. Data Link Layer and Physical Layer Specifications". This so-called DIX standard (Digital Intel Xerox)[16] specified 10 Mbit/s Ethernet, with 48-bit destination and source addresses and a global 16-bit Ethertype-type field.[17] Version 2 was published in November, 1982[18] and defines what has become known as Ethernet II. Formal standardization efforts proceeded at the same time and resulted in the publication of IEEE 802.3 on June 23, 1983.[19]

Ethernet initially competed with Token Ring and other proprietary protocols. Ethernet was able to adapt to market needs and with 10BASE2, shift to inexpensive thin coaxial cable and from 1990, to the now-ubiquitous twisted pair with 10BASE-T. By the end of the 1980s, Ethernet was clearly the dominant network technology.[4] In the process, 3Com became a major company. 3Com shipped its first 10 Mbit/s Ethernet 3C100 NIC in March 1981, and that year started selling adapters for PDP-11s and VAXes, as well as Multibus-based Intel and Sun Microsystems computers.[20]: 9  This was followed quickly by DEC's Unibus to Ethernet adapter, which DEC sold and used internally to build its own corporate network, which reached over 10,000 nodes by 1986, making it one of the largest computer networks in the world at that time.[21] An Ethernet adapter card for the IBM PC was released in 1982, and, by 1985, 3Com had sold 100,000.[14] In the 1980s, IBM's own PC Network product competed with Ethernet for the PC, and through the 1980s, LAN hardware, in general, was not common on PCs. However, in the mid to late 1980s, PC networking did become popular in offices and schools for printer and fileserver sharing, and among the many diverse competing LAN technologies of that decade, Ethernet was one of the most popular. Parallel port based Ethernet adapters were produced for a time, with drivers for DOS and Windows. By the early 1990s, Ethernet became so prevalent that Ethernet ports began to appear on some PCs and most workstations. This process was greatly sped up with the introduction of 10BASE-T and its relatively small modular connector, at which point Ethernet ports appeared even on low-end motherboards.[citation needed]

Since then, Ethernet technology has evolved to meet new bandwidth and market requirements.[22] In addition to computers, Ethernet is now used to interconnect appliances and other personal devices.[4] As Industrial Ethernet it is used in industrial applications and is quickly replacing legacy data transmission systems in the world's telecommunications networks.[23] By 2010, the market for Ethernet equipment amounted to over $16 billion per year.[24]

In February 1980, the Institute of Electrical and Electronics Engineers (IEEE) started project 802 to standardize local area networks (LAN).[14][25] The "DIX-group" with Gary Robinson (DEC), Phil Arst (Intel), and Bob Printis (Xerox) submitted the so-called "Blue Book" CSMA/CD specification as a candidate for the LAN specification.[17] In addition to CSMA/CD, Token Ring (supported by IBM) and Token Bus (selected and henceforward supported by General Motors) were also considered as candidates for a LAN standard. Competing proposals and broad interest in the initiative led to strong disagreement over which technology to standardize. In December 1980, the group was split into three subgroups, and standardization proceeded separately for each proposal.[14]

Delays in the standards process put at risk the market introduction of the Xerox Star workstation and 3Com's Ethernet LAN products. With such business implications in mind, David Liddle (General Manager, Xerox Office Systems) and Metcalfe (3Com) strongly supported a proposal of Fritz Röscheisen (Siemens Private Networks) for an alliance in the emerging office communication market, including Siemens' support for the international standardization of Ethernet (April 10, 1981). Ingrid Fromm, Siemens' representative to IEEE 802, quickly achieved broader support for Ethernet beyond IEEE by the establishment of a competing Task Group "Local Networks" within the European standards body ECMA TC24. In March 1982, ECMA TC24 with its corporate members reached an agreement on a standard for CSMA/CD based on the IEEE 802 draft.[20]: 8  Because the DIX proposal was most technically complete and because of the speedy action taken by ECMA which decisively contributed to the conciliation of opinions within IEEE, the IEEE 802.3 CSMA/CD standard was approved in December 1982.[14] IEEE published the 802.3 standard as a draft in 1983 and as a standard in 1985.[26]

Approval of Ethernet on the international level was achieved by a similar, cross-partisan action with Fromm as the liaison officer working to integrate with International Electrotechnical Commission (IEC) Technical Committee 83 and International Organization for Standardization (ISO) Technical Committee 97 Sub Committee 6. The ISO 8802-3 standard was published in 1989.[27]

Ethernet has evolved to include higher bandwidth, improved medium access control methods, and different physical media. The coaxial cable was replaced with point-to-point links connected by Ethernet repeaters or switches.[28]

Ethernet stations communicate by sending each other data packets: blocks of data individually sent and delivered. As with other IEEE 802 LANs, adapters come programmed with globally unique 48-bit MAC address so that each Ethernet station has a unique address.[b] The MAC addresses are used to specify both the destination and the source of each data packet. Ethernet establishes link-level connections, which can be defined using both the destination and source addresses. On reception of a transmission, the receiver uses the destination address to determine whether the transmission is relevant to the station or should be ignored. A network interface normally does not accept packets addressed to other Ethernet stations.[c][d]

An EtherType field in each frame is used by the operating system on the receiving station to select the appropriate protocol module (e.g., an Internet Protocol version such as IPv4). Ethernet frames are said to be self-identifying, because of the EtherType field. Self-identifying frames make it possible to intermix multiple protocols on the same physical network and allow a single computer to use multiple protocols together.[29] Despite the evolution of Ethernet technology, all generations of Ethernet (excluding early experimental versions) use the same frame formats.[30] Mixed-speed networks can be built using Ethernet switches and repeaters supporting the desired Ethernet variants.[31]

Due to the ubiquity of Ethernet, and the ever-decreasing cost of the hardware needed to support it, by 2004 most manufacturers built Ethernet interfaces directly into PC motherboards, eliminating the need for a separate network card.[32]

Shared medium

Ethernet was originally based on the idea of computers communicating over a shared coaxial cable acting as a broadcast transmission medium. The method used was similar to those used in radio systems,[e] with the common cable providing the communication channel likened to the Luminiferous aether in 19th-century physics, and it was from this reference that the name "Ethernet" was derived.[33]

Original Ethernet's shared coaxial cable (the shared medium) traversed a building or campus to every attached machine. A scheme known as carrier-sense multiple access with collision detection (CSMA/CD) governed the way the computers shared the channel. This scheme was simpler than competing Token Ring or Token Bus technologies.[f] Computers are connected to an Attachment Unit Interface (AUI) transceiver, which is in turn connected to the cable (with thin Ethernet the transceiver is usually integrated into the network adapter). While a simple passive wire is highly reliable for small networks, it is not reliable for large extended networks, where damage to the wire in a single place, or a single bad connector, can make the whole Ethernet segment unusable.[g]

Through the first half of the 1980s, Ethernet's 10BASE5 implementation used a coaxial cable 0.375 inches (9.5 mm) in diameter, later called thick Ethernet or thicknet. Its successor, 10BASE2, called thin Ethernet or thinnet, used the RG-58 coaxial cable. The emphasis was on making installation of the cable easier and less costly.[34]: 57 

Since all communication happens on the same wire, any information sent by one computer is received by all, even if that information is intended for just one destination.[h] The network interface card interrupts the CPU only when applicable packets are received: the card ignores information not addressed to it.[c] Use of a single cable also means that the data bandwidth is shared, such that, for example, available data bandwidth to each device is halved when two stations are simultaneously active.[35]

A collision happens when two stations attempt to transmit at the same time. They corrupt transmitted data and require stations to re-transmit. The lost data and re-transmission reduces throughput. In the worst case, where multiple active hosts connected with maximum allowed cable length attempt to transmit many short frames, excessive collisions can reduce throughput dramatically. However, a Xerox report in 1980 studied performance of an existing Ethernet installation under both normal and artificially generated heavy load. The report claimed that 98% throughput on the LAN was observed.[36] This is in contrast with token passing LANs (Token Ring, Token Bus), all of which suffer throughput degradation as each new node comes into the LAN, due to token waits. This report was controversial, as modeling showed that collision-based networks theoretically became unstable under loads as low as 37% of nominal capacity. Many early researchers failed to understand these results. Performance on real networks is significantly better.[37]

In a modern Ethernet, the stations do not all share one channel through a shared cable or a simple repeater hub; instead, each station communicates with a switch, which in turn forwards that traffic to the destination station. In this topology, collisions are only possible if station and switch attempt to communicate with each other at the same time, and collisions are limited to this link. Furthermore, the 10BASE-T standard introduced a full duplex mode of operation which became common with Fast Ethernet and the de facto standard with Gigabit Ethernet. In full duplex, switch and station can send and receive simultaneously, and therefore modern Ethernets are completely collision-free.

• Comparison between original Ethernet and modern Ethernet

•  

  The original Ethernet implementation: shared medium, collision-prone. All computers trying to communicate share the same cable, and so compete with each other.

•  

  Modern Ethernet implementation: switched connection, collision-free. Each computer communicates only with its own switch, without competition for the cable with others.

Repeaters and hubs

Main article: Ethernet hub

For signal degradation and timing reasons, coaxial Ethernet segments have a restricted size.[38] Somewhat larger networks can be built by using an Ethernet repeater. Early repeaters had only two ports, allowing, at most, a doubling of network size. Once repeaters with more than two ports became available, it was possible to wire the network in a star topology. Early experiments with star topologies (called Fibernet) using optical fiber were published by 1978.[39]

Shared cable Ethernet is always hard to install in offices because its bus topology is in conflict with the star topology cable plans designed into buildings for telephony. Modifying Ethernet to conform to twisted pair telephone wiring already installed in commercial buildings provided another opportunity to lower costs, expand the installed base, and leverage building design, and, thus, twisted-pair Ethernet was the next logical development in the mid-1980s.

Ethernet on unshielded twisted-pair cables (UTP) began with StarLAN at 1 Mbit/s in the mid-1980s. In 1987 SynOptics introduced the first twisted-pair Ethernet at 10 Mbit/s in a star-wired cabling topology with a central hub, later called LattisNet.[14][33]: 29 [40] These evolved into 10BASE-T, which was designed for point-to-point links only, and all termination was built into the device. This changed repeaters from a specialist device used at the center of large networks to a device that every twisted pair-based network with more than two machines had to use. The tree structure that resulted from this made Ethernet networks easier to maintain by preventing most faults with one peer or its associated cable from affecting other devices on the network.[citation needed]

Despite the physical star topology and the presence of separate transmit and receive channels in the twisted pair and fiber media, repeater-based Ethernet networks still use half-duplex and CSMA/CD, with only minimal activity by the repeater, primarily generation of the jam signal in dealing with packet collisions. Every packet is sent to every other port on the repeater, so bandwidth and security problems are not addressed. The total throughput of the repeater is limited to that of a single link, and all links must operate at the same speed.[33]: 278 

Bridging and switching

Main articles: Network bridge and Network switch

While repeaters can isolate some aspects of Ethernet segments, such as cable breakages, they still forward all traffic to all Ethernet devices. The entire network is one collision domain, and all hosts have to be able to detect collisions anywhere on the network. This limits the number of repeaters between the farthest nodes and creates practical limits on how many machines can communicate on an Ethernet network. Segments joined by repeaters have to all operate at the same speed, making phased-in upgrades impossible.[citation needed]

To alleviate these problems, bridging was created to communicate at the data link layer while isolating the physical layer. With bridging, only well-formed Ethernet packets are forwarded from one Ethernet segment to another; collisions and packet errors are isolated. At initial startup, Ethernet bridges work somewhat like Ethernet repeaters, passing all traffic between segments. By observing the source addresses of incoming frames, the bridge then builds an address table associating addresses to segments. Once an address is learned, the bridge forwards network traffic destined for that address only to the associated segment, improving overall performance. Broadcast traffic is still forwarded to all network segments. Bridges also overcome the limits on total segments between two hosts and allow the mixing of speeds, both of which are critical to the incremental deployment of faster Ethernet variants.[citation needed]

In 1989, Motorola Codex introduced their 6310 EtherSpan, and Kalpana introduced their EtherSwitch; these were examples of the first commercial Ethernet switches.[i] Early switches such as this used cut-through switching where only the header of the incoming packet is examined before it is either dropped or forwarded to another segment.[41] This reduces the forwarding latency. One drawback of this method is that it does not readily allow a mixture of different link speeds. Another is that packets that have been corrupted are still propagated through the network. The eventual remedy for this was a return to the original store and forward approach of bridging, where the packet is read into a buffer on the switch in its entirety, its frame check sequence verified and only then the packet is forwarded.[41] In modern network equipment, this process is typically done using application-specific integrated circuits allowing packets to be forwarded at wire speed.[citation needed]

When a twisted pair or fiber link segment is used and neither end is connected to a repeater, full-duplex Ethernet becomes possible over that segment. In full-duplex mode, both devices can transmit and receive to and from each other at the same time, and there is no collision domain.[42] This doubles the aggregate bandwidth of the link and is sometimes advertised as double the link speed (for example, 200 Mbit/s for Fast Ethernet).[j] The elimination of the collision domain for these connections also means that all the link's bandwidth can be used by the two devices on that segment and that segment length is not limited by the constraints of collision detection.

Since packets are typically delivered only to the port they are intended for, traffic on a switched Ethernet is less public than on shared-medium Ethernet. Despite this, switched Ethernet should still be regarded as an insecure network technology, because it is easy to subvert switched Ethernet systems by means such as ARP spoofing and MAC flooding.[citation needed][43]

The bandwidth advantages, the improved isolation of devices from each other, the ability to easily mix different speeds of devices and the elimination of the chaining limits inherent in non-switched Ethernet have made switched Ethernet the dominant network technology.[44]

Advanced networking

Simple switched Ethernet networks, while a great improvement over repeater-based Ethernet, suffer from single points of failure, attacks that trick switches or hosts into sending data to a machine even if it is not intended for it, scalability and security issues with regard to switching loops, broadcast radiation, and multicast traffic.[citation needed]

Advanced networking features in switches use shortest path bridging (SPB) or the spanning-tree protocol (STP) to maintain a loop-free, meshed network, allowing physical loops for redundancy (STP) or load-balancing (SPB). Shortest path bridging includes the use of the link-state routing protocol IS-IS to allow larger networks with shortest path routes between devices.

Advanced networking features also ensure port security, provide protection features such as MAC lockdown[45] and broadcast radiation filtering, use VLANs to keep different classes of users separate while using the same physical infrastructure, employ multilayer switching to route between different classes, and use link aggregation to add bandwidth to overloaded links and to provide some redundancy.[citation needed]

In 2016, Ethernet replaced InfiniBand as the most popular system interconnect of TOP500 supercomputers.[46]

Main articles: Ethernet physical layer and Ethernet over twisted pair

The Ethernet physical layer evolved over a considerable time span and encompasses coaxial, twisted pair and fiber-optic physical media interfaces, with speeds from 1 Mbit/s to 400 Gbit/s.[47] The first introduction of twisted-pair CSMA/CD was StarLAN, standardized as 802.3 1BASE5.[48] While 1BASE5 had little market penetration, it defined the physical apparatus (wire, plug/jack, pin-out, and wiring plan) that would be carried over to 10BASE-T through 10GBASE-T.

The most common forms used are 10BASE-T, 100BASE-TX, and 1000BASE-T. All three use twisted-pair cables and 8P8C modular connectors. They run at 10 Mbit/s, 100 Mbit/s, and 1 Gbit/s, respectively.[49][50][51]

Fiber optic variants of Ethernet (that commonly use SFP modules) are also very popular in larger networks, offering high performance, better electrical isolation and longer distance (tens of kilometers with some versions). In general, network protocol stack software will work similarly on all varieties.[52]

Main article: Ethernet frame

In IEEE 802.3, a datagram is called a packet or frame. Packet is used to describe the overall transmission unit and includes the preamble, start frame delimiter (SFD) and carrier extension (if present).[k] The frame begins after the start frame delimiter with a frame header featuring source and destination MAC addresses and the EtherType field giving either the protocol type for the payload protocol or the length of the payload. The middle section of the frame consists of payload data including any headers for other protocols (for example, Internet Protocol) carried in the frame. The frame ends with a 32-bit cyclic redundancy check, which is used to detect corruption of data in transit.[53]: sections 3.1.1 and 3.2  Notably, Ethernet packets have no time-to-live field, leading to possible problems in the presence of a switching loop.

Main article: Autonegotiation

Autonegotiation is the procedure by which two connected devices choose common transmission parameters, e.g. speed and duplex mode. Autonegotiation was initially an optional feature, first introduced with 100BASE-TX, while it is also backward compatible with 10BASE-T. Autonegotiation is mandatory for 1000BASE-T and faster.

Main article: Switching loop

A switching loop or bridge loop occurs in computer networks when there is more than one Layer 2 (OSI model) path between two endpoints (e.g. multiple connections between two network switches or two ports on the same switch connected to each other). The loop creates broadcast storms as broadcasts and multicasts are forwarded by switches out every port, the switch or switches will repeatedly rebroadcast the broadcast messages flooding the network. Since the Layer 2 header does not support a time to live (TTL) value, if a frame is sent into a looped topology, it can loop forever.[54]

A physical topology that contains switching or bridge loops is attractive for redundancy reasons, yet a switched network must not have loops. The solution is to allow physical loops, but create a loop-free logical topology using the shortest path bridging (SPB) protocol or the older spanning tree protocols (STP) on the network switches.[citation needed]

Jabber

A node that is sending longer than the maximum transmission window for an Ethernet packet is considered to be jabbering. Depending on the physical topology, jabber detection and remedy differ somewhat.

• An MAU is required to detect and stop abnormally long transmission from the DTE (longer than 20–150 ms) in order to prevent permanent network disruption.[55]
• On an electrically shared medium (10BASE5, 10BASE2, 1BASE5), jabber can only be detected by each end node, stopping reception. No further remedy is possible.[56]
• A repeater/repeater hub uses a jabber timer that ends retransmission to the other ports when it expires. The timer runs for 25,000 to 50,000 bit times for 1 Mbit/s,[57] 40,000 to 75,000 bit times for 10 and 100 Mbit/s,[58][59] and 80,000 to 150,000 bit times for 1 Gbit/s.[60] Jabbering ports are partitioned off the network until a carrier is no longer detected.[61]
• End nodes utilizing a MAC layer will usually detect an oversized Ethernet frame and cease receiving. A bridge/switch will not forward the frame.[62]
• A non-uniform frame size configuration in the network using jumbo frames may be detected as jabber by end nodes.[citation needed]
• A packet detected as jabber by an upstream repeater and subsequently cut off has an invalid frame check sequence and is dropped.[citation needed]

Runt frames

• Runts are packets or frames smaller than the minimum allowed size. They are dropped and not propagated.[63]

• 5-4-3 rule
• Chaosnet
• Ethernet crossover cable
• Fiber media converter
• ISO/IEC 11801
• Link Layer Discovery Protocol
• List of device bit rates
• LocalTalk
• PHY
• Point-to-point protocol over Ethernet (PPPoE)
• Sneakernet
• Wake-on-LAN (WoL)

1. ^ The experimental Ethernet described in the 1976 paper ran at 2.94 Mbit/s and has eight-bit destination and source address fields, so the original Ethernet addresses are not the MAC addresses they are today.[11] By software convention, the 16 bits after the destination and source address fields specify a "packet type", but, as the paper says, "different protocols use disjoint sets of packet types". Thus the original packet types could vary within each different protocol. This is in contrast to the EtherType in the IEEE Ethernet standard, which specifies the protocol being used.
2. ^ In some cases, the factory-assigned address can be overridden, either to avoid an address change when an adapter is replaced or to use locally administered addresses.
3. ^ a b Unless it is put into promiscuous mode.
4. ^ Of course bridges and switches will accept other addresses for forwarding the packet.
5. ^ There are fundamental differences between wireless and wired shared-medium communication, such as the fact that it is much easier to detect collisions in a wired system than a wireless system.
6. ^ In a CSMA/CD system packets must be large enough to guarantee that the leading edge of the propagating wave of a message gets to all parts of the medium and back again before the transmitter stops transmitting, guaranteeing that collisions (two or more packets initiated within a window of time that forced them to overlap) are discovered. As a result, the minimum packet size and the physical medium's total length are closely linked.
7. ^ Multipoint systems are also prone to strange failure modes when an electrical discontinuity reflects the signal in such a manner that some nodes would work properly, while others work slowly because of excessive retries or not at all. See standing wave for an explanation. These could be much more difficult to diagnose than a complete failure of the segment.
8. ^ This one speaks, all listen property is a security weakness of shared-medium Ethernet, since a node on an Ethernet network can eavesdrop on all traffic on the wire if it so chooses.
9. ^ The term switch was invented by device manufacturers and does not appear in the IEEE 802.3 standard.
10. ^ This is misleading, as performance will double only if traffic patterns are symmetrical.
11. ^ The carrier extension is defined to assist collision detection on shared-media gigabit Ethernet.

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43. ^ Wang, Shuangbao Paul; Ledley, Robert S. (October 25, 2012). Computer Architecture and Security: Fundamentals of Designing Secure Computer Systems. John Wiley & Sons. ISBN 978-1-118-16883-7. Archived from the original on March 15, 2021. Retrieved October 2, 2020.
44. ^ "Token Ring-to-Ethernet Migration". Cisco. Archived from the original on July 8, 2011. Retrieved October 22, 2010. Respondents were first asked about their current and planned desktop LAN attachment standards. The results were clear—switched Fast Ethernet is the dominant choice for desktop connectivity to the network
45. ^ David Davis (October 11, 2007). "Lock down Cisco switch port security". Archived from the original on July 31, 2020. Retrieved April 19, 2020.
46. ^ "HIGHLIGHTS – JUNE 2016". June 2016. Archived from the original on January 30, 2021. Retrieved February 19, 2021. InfiniBand technology is now found on 205 systems, down from 235 systems, and is now the second most-used internal system interconnect technology. Gigabit Ethernet has risen to 218 systems up from 182 systems, in large part thanks to 176 systems now using 10G interfaces.
47. ^ "[STDS-802-3-400G] IEEE P802.3bs Approved!". IEEE 802.3bs Task Force. Archived from the original on June 12, 2018. Retrieved December 14, 2017.
48. ^ "1BASE5 Medium Specification (StarLAN)". cs.nthu.edu.tw. December 28, 1996. Archived from the original on July 10, 2015. Retrieved November 11, 2014.
49. ^ IEEE 802.3 14. Twisted-pair medium attachment unit (MAU) and baseband medium, type 10BASE-T including type 10BASE-Te
50. ^ IEEE 802.3 25. Physical Medium Dependent (PMD) sublayer and baseband medium, type 100BASE-TX
51. ^ IEEE 802.3 40. Physical Coding Sublayer (PCS), Physical Medium Attachment (PMA) sublayer and baseband medium, type 1000BASE-T
52. ^ IEEE 802.3 4.3 Interfaces to/from adjacent layers
53. ^ "802.3-2012 – IEEE Standard for Ethernet" (PDF). ieee.org. IEEE Standards Association. December 28, 2012. Archived from the original on February 23, 2014. Retrieved February 8, 2014.
54. ^ "Layer 2 Switching Loops in Network Explained". ComputerNetworkingNotes. Retrieved January 8, 2022.
55. ^ IEEE 802.3 8.2 MAU functional specifications
56. ^ IEEE 802.3 8.2.1.5 Jabber function requirements
57. ^ IEEE 802.3 12.4.3.2.3 Jabber function
58. ^ IEEE 802.3 9.6.5 MAU Jabber Lockup Protection
59. ^ IEEE 802.3 27.3.2.1.4 Timers
60. ^ IEEE 802.3 41.2.2.1.4 Timers
61. ^ IEEE 802.3 27.3.1.7 Receive jabber functional requirements
62. ^ IEEE 802.1 Table C-1—Largest frame base values
63. ^ "Troubleshooting Ethernet". Cisco. Retrieved May 18, 2021.

• Digital Equipment Corporation; Intel Corporation; Xerox Corporation (September 1980). "The Ethernet: A Local Area Network". ACM SIGCOMM Computer Communication Review. 11 (3): 20. doi:10.1145/1015591.1015594. S2CID 31441899. Version 1.0 of the DIX specification.
• "Ethernet Technologies". Internetworking Technology Handbook. Cisco Systems. Retrieved April 11, 2011.
• Charles E. Spurgeon (2000). Ethernet: The Definitive Guide. O'Reilly Media. ISBN 978-1565-9266-08.
• Yogen Dalal. "Ethernet History". blog.

Wikimedia Commons has media related to Ethernet.

• IEEE 802.3 Ethernet working group
• IEEE 802.3-2015 – superseded
• IEEE 802.3-2018 standard

After reading an article on ALOHAnet, Robert Metcalfe became interested in computer networking. ALOHAnet was an over-the-air wide area network system in Hawaii using ultra high frequency radios and made several assumptions that Metcalfe thought would not be correct in practice. He developed his own theories of how to manage traffic, and began to consider an "ALOHAnet in a wire" networking system. In 1972, he joined Xerox PARC to develop these ideas, and after pairing up with David Boggs, the two had early 3 Mbit/s versions of Ethernet working in 1973. They then went on to build up a networking protocol known as PARC Universal Packet (PuP), with the entire system ready for build-out by late 1974.[4]

At this point, Xerox management did nothing with it, even after being approached by prospective customers. Increasingly upset by management's lack of interest, Metcalfe left Xerox in 1975, but he was lured back again the next year. Further development followed, resulting in the seminal Xerox Network Systems (XNS) protocol, which was completed by 1978. Once again, Metcalfe found that management was unwilling to actually do anything with the product, and he threatened to leave and in 1979 he left the company.[4]

Founding and early days (1979–1996)

Metcalfe subsequently co-founded 3Com in 1979.[1] The other co-founders were Metcalfe's college friend Howard Charney and two others.[1] Bill Krause joined as President in 1981 and became CEO in 1982 and led 3Com until 1992 when he retired. 3Com began making Ethernet adapter cards for many early 1980s computer systems, including the DEC LSI-11, DEC VAX-11 and the IBM PC. In the mid-1980s, 3Com branded their Ethernet technology as EtherSeries, while introducing a range of software and PC-based equipment to provide shared services over a local area network (LAN) using XNS protocols. These protocols were branded EtherShare (for file sharing), EtherPrint (for printing), EtherMail (for email), and Ether-3270 (for IBM host emulation).

The company's network software products included:

• 3+Share file and printer sharing.
• 3+Mail e-mail.
• 3+Remote for routing XNS over a PC serial port.
• NetConnect for routing XNS between Ethernets.
• MultiConnect (?) was a chassis-based multi-port 10BASE2 Ethernet repeater.
• 3Server, a server-grade PC for running 3+ services.
• 3Station, a diskless workstation.
• 3+Open file and printer sharing (based on Microsoft's LAN Manager).
• Etherterm terminal emulation.
• Etherprobe LAN analysis software.
• DynamicAccess software products for Ethernet load balancing, response time, and RMON II distributed monitoring.

3Com's expansion beyond its original base of PC and thin Ethernet products began in 1987 when it merged with Bridge Communications. This provided a range of equipment based on Motorola 68000 processors and using XNS protocols compatibly with 3Com's Etherterm PC software.

• CS/1, CS/200 communication servers ("terminal servers")
• Ethernet bridges and XNS routers
• GS/1-X.25 X.25 gateway
• CS/1-SNA SNA gateway
• NCS/1 network control software running on a Sun Microsystems computer

By 1995, 3Com's status was such that they were able to enter into an agreement with the city of San Francisco to pay $900,000 per year for the naming rights to Candlestick Park. That agreement ended in 2002.

1997–2000

In 1997, 3Com merged with USRobotics (USR), a maker of dial-up modems, and owner of Palm, Inc. USRobotics was known for its Sportster line of consumer-oriented modems, as well as its Courier business-class modem line. This merger spelled the beginning of the end of 3Com. In addition to consumer network electronics, USRobotics was a well-known manufacturer of a dialup access server, the "Total Control Hub", rebadged by 3Com as the "Total Control 1000", based largely on its Courier modem technology. This key business product competed against Cisco's AS5200 access server line in the mid-1990s as the explosion of the Internet led to service provider investment in dialup access server equipment. 3Com continued the development of the Total Control line until it was eventually spun off as a part of Commworks, which was then acquired by UTStarcom.[5]

In August 1998, Bruce Claflin was named chief operating officer. The modem business was rapidly shrinking. 3Com attempted to enter the DSL business, but was not successful.

In the lucrative server network interface card (NIC) business, 3Com dominated market share, with Intel only able to break past 3Com after dramatic price slashing. It started developing Gigabit Ethernet cards in-house but later scrapped the plans. Later, it formed a joint venture with Broadcom, where Broadcom would develop the main integrated circuit component and the NIC would be 3Com branded.

In 1999, 3Com acquired NBX, a Boston company with an Ethernet-based phone system for small and medium-sized businesses. This product proved popular with 3Com's existing distribution channel and saw rapid growth and adoption. As one of the first companies to deliver a complete networked phone system, and increased its distribution channel with larger telephony partners such as Southwestern Bell and Metropark Communications, 3Com helped make VoIP into a safe and practical technology with wide adoption.

3Com then tried to move into the smart consumer appliances business and in June 2000, 3Com acquired internet radio startup Kerbango for $80 million. It developed its Audrey appliance, which made an appearance on The Oprah Winfrey Show. It scrapped the Audrey and Kerbango products less than a year later.

In March 2000, in a highly public and criticized move, 3Com exited the high-end core routers and switch market to focus on other areas of the business.[6] The CoreBuilder Ethernet and ATM LAN switches, PathBuilder and NetBuilder WAN Routers were all discontinued June 2000. CoreBuilder products and the customer base was migrated over to Extreme Networks. The PathBuilder and NetBuilder were transitioned to Motorola. 3Com focused its efforts from 2000 to 2003 on building up the HomeConnect, OfficeConnect, SuperStack, NBX and Total Control product lines. Due to this perceived exit from the Enterprise market, 3Com would never gain momentum with large customers or carriers again.

In July 2000, 3Com spun off Palm as an independent company. After the IPO, 3Com still owned 80% of Palm, but 3Com's market capitalization was smaller than Palm's. U.S. Robotics was also spun out again as a separate company at this time.

2001 and beyond

In January 2001, Claflin became chief executive officer, replacing Éric Benhamou, CEO from 1990 to 2000. He was criticized for the costly diversification in the mobile handheld computer market. At this point, the company's main cash-cow, the network interface card business, was also shrinking rapidly, mainly because the functionality was integrated into the southbridge of many motherboards. The company started slashing or selling divisions and going through numerous rounds of layoffs. The company went from employing more than 12,000 employees to fewer than 2,000.

In May 2003, the company moved its Silicon Valley Santa Clara headquarters to Marlborough, Massachusetts. It also formed a venture called H3C with Huawei, whereby 3Com would sell and rebrand products under the joint venture.[7]

In 2003, 3Com sold its CommWorks Corporation subsidiary to UTStarcom, Inc. CommWorks was based in Rolling Meadows, Illinois, and developed wireline telecommunications and wireless infrastructure technologies.[8]

In January 2006, Claflin announced he would be leaving the company. In January 2006, R Scott Murray became CEO of 3Com and chairman of H3C Technology in China, the joint venture with Huawei Technologies. Murray voluntarily resigned from the company in August 2006 over his concerns about the questionable business ethics of Huawei and potential cyber security risks posed by Huawei. Edgar Masri returned to 3Com to head as president and CEO following Murray's departure.

In September 2007, Bain Capital agreed to buy the company for $2.2 billion, with minority equity financing from Huawei Technologies. However, the deal met with U.S. government regulatory opposition and it fell through early in 2008, following concerns over Huawei's risk of conducting cyber security threats against the United States Government and its allies, Huawei's former dealings in Iran, and Huawei being operated by a former engineer[9] in China's People's Liberation Army.[10][11] Edgar Masri left the company in April 2008, partially as a result of the failed Bain transaction.

In April 2008, Robert Mao was named chief executive, and Ron Sege president and chief operating officer.[12]

In fiscal year 2008 ended May 30, 2008, 3Com had annual revenue of $1.3 billion and more than 6,000 employees in over 40 countries. In September 2008, 3Com reported financial results for its fiscal 2009 first quarter, which ended August 29, 2008. Revenue in the quarter was $342.7 million compared to revenue of $319.4 million in the corresponding period in fiscal 2008, a 7 percent increase. Net income in the quarter was $79.8 million, compared with a net loss of $18.7 million in the first quarter of fiscal year 2008.[13]

The company reported that it had more than 2,700 engineers, with more than 1,400 United States patents and nearly 180 Chinese-issued patents, as well as more than 1050 pending Chinese applications. It also reported pending applications for 35 separate inventions outside of China covering a wide range of networking technologies.

Acquisition by HP

On November 11, 2009, 3Com and Hewlett-Packard announced that Hewlett-Packard would acquire 3Com for $2.7 billion in cash.[14] On April 12, 2010, Hewlett-Packard completed its acquisition.[3] When Hewlett-Packard split into Hewlett Packard Enterprise and Hewlett-Packard Inc., the 3Com unit continued with HPE and was ultimately integrated into Aruba Networks along with the rest of HP's networking portfolio.

Main article: 3Com Products

• Fixed configuration Ethernet switches including stackable switches: 3Com brand Gigabit switches Switch 5500G, 4800G, 4500G, 4200G, Baseline, OfficeConnect; 3Com brand Fast Ethernet switches Switch 5500, 4500, 4210, Baseline, OfficeConnect; H3C brand switches S5600, S5500, S5100, S3600, S3610, S3100.
• Modular Chassis switches: 3Com brand 8800, 7900E, 7500. H3C brand S9500, S7500, S7500E.
• Wide area network routers
• Wireless access points, adapters, and connectivity products
• Internet access gateways and firewalls, both wired and wireless
• Network management applications
• Network security platforms including the TippingPoint Intrusion Prevention System.
• IP Telephony applications including PBX and Computer Telephony Integration. Telecommunications products utilized Voice over Internet Protocol and Session Initiation Protocol (SIP). Voice platforms included VCX and NBX.
• Local area network interface cards
• IP Video Surveillance and Network Storage (marketed in China, South Africa, South America and other key markets)
• Consumer USB webcams and associated software (3Com HomeConnect)
• The 3Com Laser Library which, at the time, was a revolutionary CD based documentation and tech support tool (brain child of Dirk Martin)

3Com came close to merging with computer maker Convergent Technologies, abandoning the pact just two days before a vote was scheduled in March 1986.[15] Later, 3Com went on to acquire the following:

• Bridge Communications in 1987
• BICC Data Networks in 1992
• Star-Tek in 1993
• Synernetics in 1993
• Centrum in 1994
• NiceCom in 1994
• AccessWorks, Sonix Communications, Primary Access, and Chipcom in 1995
• Axon Networks and OnStream Networks in 1996
• USRobotics merger/acquisition in 1997 (included product lines: Sportster, Courier, Palm, Megahertz, Conferencelink, Audrey, and more)
• NBX in 1999
• Kerbango in 2000
• TippingPoint in 2005
• Huawei-3Com (H3C) in 2007 (Bought out Huawei's 49% stake for US$882 million from a 2003 joint venture)

Former subsidiaries

CommWorks Corporation was a subsidiary of 3Com Corporation, based in Rolling Meadows, Illinois. It was sold to UTStarcom of Alameda, California in 2003.

CommWorks was formerly the Carrier Network Business unit of 3Com, comprising several acquired companies: U.S. Robotics (Rolling Meadows, Illinois),[16] Call Technologies (Reston, Virginia),[17] and LANsource (Toronto, Ontario, Canada).[18] CommWorks was able to use technology from each company to create IP softswitch and IP communications software. U.S. Robotics provided media gateways (the Total Control 1000 product line, formerly used for dial-modem termination) and softswitch technology. Call Technologies provided Unified Messaging software. LANsource provided fax-over-IP software that was integrated with the Unified Messaging platform.

The Carrier Network Business unit of 3Com developed an Inter-working function technology that became the first and dominant 2G CDMA wireless data gateway product. In partnership with Unwired Planet (now Openwave) and Qualcomm Quicknet connect allowed for 6 second connect times versus modems connecting the call in approximately 30 seconds.[19] This product was deployed in the United States, Japan,[20] and Korea covering the 2G CDMA market sample carriers included Sprint.[21] It led to follow on products that became core to CommWorks now UTStarcom offerings including the 2.5 and 3G packet data gateway products known as PDSN and Home Agents.

CommWorks/3Com co-developed an H.323-based softswitch with AT&T in 1998 for use in a "transparent trunking" application for AT&T's residential long-distance customers.[22] Long distance telephone calls were redirected from the LEC's ingress CLASS 5 switch to the Total Control 1000 media gateway, where it was converted from TDM to IP and transported across AT&T's WorldNet IP backbone. When it reached the destination, it was passed to the egress LEC's CLASS 5 switch as an untariffed data call.

CommWorks modified the gateway and softswitch software to support SIP for MCI/WorldCom's hosted business offering in 2000.[23]

Although 3Com sold CommWorks to UTStarcom,[24] they retained intellectual property rights to the softswitch technology. After modifying the software to enable enterprise PBX features, 3Com released this technology as VCX, the industry's first pure SIP PBX, in 2003.[25]

• 3Station
• Busy Override
• List of acquisitions by Hewlett-Packard

1. ^ a b c d e f Hedden, Heather Behn; Salamie, David E.; Meyer, Stephen (2010) [previous versions appeared in vol.11 and 34]. Jacques, Derek; Kepos, Paula (eds.). "3Com Corporation". International Directory of Company Histories. Farmington Hills, Michigan: St. James Press (Gale, Cengage Learning group). 106: 465–466. ISBN 978-1-55862-640-9.
2. ^ "Bob Metcalfe: Serial Innovator". The Henry Ford.
3. ^ a b "HP Completes Acquisition of 3Com Corporation, Accelerates Converged Infrastructure Strategy". News release. Hewlett-Packard. April 12, 2010. Retrieved August 27, 2011.
4. ^ a b Pelkey 2007, 6.7.
5. ^ "3Com / USR/ UTStar Total Control Access Server". ISPTrader web site. Archived from the original on 13 July 2011. Retrieved August 27, 2011.
6. ^ Jim Duffy (March 20, 2000). "3Com exits enterprise network stage". Network World. Archived from the original on 15 October 2012. Retrieved September 1, 2011.
7. ^ "3Com to Move Out of Silicon Valley". Los Angeles Times. 6 May 2003. Archived from the original on 2021-03-14. Retrieved 24 June 2021.
8. ^ Hooper, Larry (2003-03-06). "Partners Praise 3Com Growth Plan". CRN. Retrieved 2021-06-24.
9. ^ Sherisse Pham (2019). "Who is Huawei founder Ren Zhengfei?". CNN. Retrieved 2019-05-20.
10. ^ Bray, Hiawatha (29 September 2007). "3Com goes private in Bain, Huawei deal". The Boston Globe.
11. ^ Deal to Buy 3Com Falls Apart - About.com Archived February 18, 2012, at the Wayback Machine
12. ^ 3Com Announces Senior Leadership Changes to Accelerate Global Business Plan
13. ^ "News Releases". Archived from the original on 2015-09-04. Retrieved 2008-10-27.
14. ^ "Press Release". Hewlett-Packard. Archived from the original on 2011-03-13.
15. ^ Pollack, Andrew (27 March 1986). "CONVERGENT, 3COM FAIL IN MERGER PLAN". The New York Times. Retrieved 17 May 2021.
16. ^ "3Com acquires U.S. Robotics". news.cnet.com.
17. ^ 3Com Corporation Acquires Leading Unified Messaging Vendor, Call Technologies; Company Accelerates Delivery of Carrier-Class, CommWorks Architecture. - Business Wire - HighBeam Research Archived May 16, 2011, at the Wayback Machine
18. ^ "3Com Completes Acquisition of LANSource Technologies, Inc — Company Business and Marketing". Edge: Work-Group Computing Report. 1999. Archived from the original on 2012-06-29.
19. ^ Qualcomm Press Center- 3COM Corporation, Qualcomm and Unwired Planet Announce Quick Network Connect Technology: Internet Access For CDMA Networks
20. ^ "Motorola Provides 64Kbps WAP Access On cdmaOne Networks". MobileTechNews.
21. ^ "3Com Supplies Critical Wireless Technology for New Sprint Wireless Web Service — Sprint's PCS Wireless Web service — Company Business and Marketing". Cambridge Telcom Report. 1999. Archived from the original on 2012-06-29.
22. ^ [1] Archived December 16, 2006, at the Wayback Machine
23. ^ WorldCom. "WorldCom Presents Plans for Commercial IP Communications Services".
24. ^ "UTStarcom Cops CommWorks - Light Reading".
25. ^ [2] Archived July 16, 2011, at the Wayback Machine

• James Pelkey, "Entrepreneurial Capitalism and Innovation: A History of Computer Communications 1968-1988", 2007

Wikimedia Commons has media related to 3Com.

• HPE Networking
• Aruba Networks
• H3C Technologies
• "3Com: Routers, Switches, VoIP, Wireless, Network Management". Official web site. Archived from the original on 1996-10-23.

• Eric Benhamou and the Turnaround of 3Com - interview with Sramanamitra.com