工程师 Mark Kempf 的无名创新改变了以太网，推动了交换的兴起

罗伯特·梅特卡夫和大卫·博格斯发明的以太网对世界产生了重大影响，导致了各种网络技术的发展和进步。然而，完整的故事涉及 Mark Kempf 在 1983 年创建的学习桥，它通过实现数据存储和转发交换彻底改变了 LAN 技术。这项创新使现有以太网能够轻松升级并提高其性能，从而逐渐从基于 CSMA/CD 的同轴电缆转向专用铜缆和光纤链路。 Kempf 的发明和随后的标准化工作为以太网的广泛采用和持续发展奠定了基础，以太网至今仍是占主导地位的 LAN 技术。

Ethernet's Evolutionary Journey: The Unsung Role of Mark Kempf and the Rise of Switching

以太网的演变之旅：Mark Kempf 的无名角色和交换的兴起

Ethernet, a ubiquitous technology that underpins the internet and countless other applications, celebrates its 50th anniversary this year. While the invention of Carrier Sense Multiple Access with Collision Detection (CSMA/CD) by Robert Metcalfe and David Boggs is widely recognized as a pivotal moment in Ethernet's history, the contributions of others who shaped its evolution are often overlooked. Among them, Mark Kempf stands out as a visionary engineer whose innovations transformed Ethernet from a shared media technology to the high-performance, switched network we know today.

以太网是一项支撑互联网和无数其他应用的无处不在的技术，今年迎来了它的 50 周年纪念。虽然 Robert Metcalfe 和 David Boggs 发明的带冲突检测的载波侦听多路访问 (CSMA/CD) 被广泛认为是以太网历史上的关键时刻，但其他塑造其发展的人的贡献却常常被忽视。其中，马克·肯普夫 (Mark Kempf) 作为一位富有远见的工程师脱颖而出，他的创新将以太网从共享媒体技术转变为我们今天所知的高性能交换网络。

The Quest for Speed and the Threat from FDDI

对速度的追求和来自 FDDI 的威胁

In the 1980s, the limitations of CSMA/CD Ethernet became increasingly apparent as the demand for faster network speeds grew. A coalition of companies, including Digital Equipment Corporation (DEC), embarked on the development of a new standard, Fiber Distributed Data Interface (FDDI), which promised speeds of 100 Mb/s over optical fiber. FDDI seemed poised to supplant Ethernet as the dominant LAN technology.

20 世纪 80 年代，随着对更快网络速度的需求增长，CSMA/CD 以太网的局限性变得越来越明显。包括数字设备公司 (DEC) 在内的公司联盟开始开发新标准光纤分布式数据接口 (FDDI)，该标准承诺通过光纤实现 100 Mb/s 的速度。 FDDI 似乎准备取代以太网成为占主导地位的 LAN 技术。

A New Approach: Store-and-Forward Switching

新方法：存储转发交换

However, Kempf, a principal engineer at DEC, believed there was a better way. Instead of developing a faster version of Ethernet or adopting FDDI, he proposed a novel approach: store-and-forward switching.

然而，DEC 的首席工程师 Kempf 相信有更好的方法。他没有开发更快的以太网版本或采用 FDDI，而是提出了一种新颖的方法：存储转发交换。

In a store-and-forward switch, each message is received and stored in a buffer before being transmitted to its destination. This eliminates the need for collision detection, enabling higher speeds and eliminating the need for a shared medium.

在存储转发交换机中，每条消息在发送到目的地之前都会被接收并存储在缓冲区中。这消除了碰撞检测的需要，从而实现了更高的速度并消除了对共享介质的需要。

The Birth of the Learning Bridge

学习桥的诞生

Kempf's idea took shape in a collaboration with Bob Shelly, a software engineer. Together, they developed the concept of a "learning bridge," a device that would connect multiple Ethernet LANs and selectively forward packets based on their destination MAC addresses.

肯普夫的想法是在与软件工程师鲍勃·谢利 (Bob Shelly) 的合作中形成的。他们共同开发了“学习桥”的概念，这是一种连接多个以太网 LAN 并根据数据包的目标 MAC 地址有选择地转发数据包的设备。

The learning bridge had several advantages. It allowed easy upgrades of existing Ethernet networks, isolated heavy traffic to specific segments, and doubled the effective cable length limit. Most importantly, it removed the performance bottlenecks inherent in shared media access protocols.

学习桥有几个优点。它允许轻松升级现有以太网网络，将大量流量隔离到特定网段，并将有效电缆长度限制加倍。最重要的是，它消除了共享媒体访问协议固有的性能瓶颈。

Overcoming Obstacles and Gaining Acceptance

克服障碍并获得认可

Kempf's innovation faced several challenges. One was the risk of packets looping indefinitely in misconfigured networks. However, Radia Perlman, another DEC engineer, provided a solution: the spanning tree protocol, which ensures that bridges form a tree-like topology, preventing loops.

肯普夫的创新面临着多项挑战。其中之一是数据包在配置错误的网络中无限循环的风险。然而，另一位 DEC 工程师 Radia Perlman 提供了一个解决方案：生成树协议，它可以确保网桥形成树状拓扑，防止环路。

Another challenge was the need for high-performance hardware to process packets at wire speed. Kempf designed a custom hardware engine using programmable array logic (PAL) devices to achieve the required performance.

另一个挑战是需要高性能硬件以线速处理数据包。 Kempf 使用可编程阵列逻辑 (PAL) 器件设计了定制硬件引擎，以实现所需的性能。

Despite these challenges, Kempf's bridge technology was groundbreaking. In 1986, DEC introduced the LANBridge 100, the first commercial learning bridge. It allowed existing CSMA/CD coax-based Ethernets to be upgraded to much higher speeds.

尽管面临这些挑战，Kempf 的电桥技术仍具有开创性。 1986 年，DEC 推出了 LANBridge 100，这是第一款商用学习桥。它允许现有的基于 CSMA/CD 同轴电缆的以太网升级到更高的速度。

The Gradual Migration to Switched Ethernet

逐步迁移到交换以太网

Kempf's bridge technology did not replace Ethernet but rather complemented it. By allowing store-and-forward switching between existing Ethernets, bridges paved the way for a gradual migration away from CSMA/CD over coax to the now ubiquitous copper and fiber links between individual computers and a dedicated switch port.

Kempf 的桥接技术并没有取代以太网，而是对其进行了补充。通过允许现有以太网之间的存储转发交换，网桥为从同轴电缆上的 CSMA/CD 逐步迁移到单个计算机和专用交换机端口之间现在无处不在的铜缆和光纤链路铺平了道路。

The speed of the links is no longer limited by the constraints of collision detection. Over time, the change completely transformed how people think of Ethernet.

链接的速度不再受到碰撞检测的限制。随着时间的推移，这一变化彻底改变了人们对以太网的看法。

The Impact of Switching Technology

交换技术的影响

The existence of bridges with increasingly higher performance effectively rendered new shared media LAN access protocols obsolete. FDDI later faded from the marketplace in the face of faster Ethernet versions.

性能越来越高的网桥的存在有效地使新的共享媒体 LAN 访问协议变得过时。后来，面对更快的以太网版本，FDDI 从市场上消失了。

Bridge technology also enabled the development of more advanced networking features, such as virtual LANs (VLANs) and support for multiple network protocols. These enhancements further contributed to Ethernet's longevity and popularity.

桥接技术还促进了更高级网络功能的开发，例如虚拟 LAN (VLAN) 和对多种网络协议的支持。这些增强功能进一步促进了以太网的寿命和普及。

The Lasting Legacy of Mark Kempf

马克·肯普夫的持久遗产

Kempf's invention of the learning bridge played a pivotal role in the evolution of Ethernet. It transformed Ethernet from a shared media technology into a switched network, paving the way for the high-speed, reliable, and efficient networks we use today.

肯普夫发明的学习桥在以太网的发展过程中发挥了关键作用。它将以太网从共享媒体技术转变为交换网络，为我们今天使用的高速、可靠和高效的网络铺平了道路。

Kempf's contributions have not received the widespread recognition they deserve. However, his invention has had a profound impact on the development of the internet and the entire digital landscape.

肯普夫的贡献尚未得到应有的广泛认可。然而，他的发明对互联网和整个数字领域的发展产生了深远的影响。

Ethernet's enduring success is a testament to the power of innovation and the foresight of engineers like Mark Kempf. As we celebrate its 50th anniversary, it is important to remember the unsung heroes who shaped its history and continue to drive its evolution.

以太网的持久成功证明了创新的力量和马克·肯普夫等工程师的远见。在我们庆祝其成立 50 周年之际，重要的是要记住那些塑造了其历史并继续推动其发展的无名英雄。