工程師 Mark Kempf 的無名創新改變了以太網，推動了交換的興起

羅伯特·梅特卡夫和大衛·博格斯發明的乙太網路對世界產生了重大影響，導致了各種網路技術的發展和進步。然而，完整的故事涉及 Mark Kempf 在 1983 年創建的學習橋，它透過實現資料儲存和轉送交換徹底改變了 LAN 技術。這項創新使現有乙太網路能夠輕鬆升級並提高其性能，從而逐漸從基於 CSMA/CD 的同軸電纜轉向專用銅纜和光纖鏈路。 Kempf 的發明和隨後的標準化工作為乙太網路的廣泛採用和持續發展奠定了基礎，乙太網路至今仍是主導的 LAN 技術。

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

乙太網路的演進之旅：Mark Kempf 的無名角色和交換的興起

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.

乙太網路是一項支撐互聯網和無數其他應用的無處不在的技術，今年迎來了它的 50 週年紀念。雖然 Robert Metcalfe 和 David Boggs 發明的帶有衝突檢測的載波偵聽多路訪問 (CSMA/CD) 被廣泛認為是以太網歷史上的關鍵時刻，但其他塑造其發展的人的貢獻卻常常被忽視。其中，馬克肯普夫 (Mark Kempf) 作為一位富有遠見的工程師脫穎而出，他的創新將乙太網路從共享媒體技術轉變為我們今天所知的高效能交換網路。

The Quest for Speed and the Threat from FDDI

對速度的追求和來自 FDDI 的威脅

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.

1980 年代，隨著對更快網路速度的需求增長，CSMA/CD 乙太網路的限制變得越來越明顯。包括數位設備公司 (DEC) 在內的公司聯盟開始開發新標準光纖分散式資料介面 (FDDI)，該標準承諾透過光纖實現 100 Mb/s 的速度。 FDDI 似乎準備取代乙太網路成為主導的 LAN 技術。

A New Approach: Store-and-Forward Switching

新方法：儲存轉送交換

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 的首席工程師 Kempf 相信有更好的方法。他沒有開發更快的乙太網路版本或採用 FDDI，而是提出了一種新穎的方法：儲存轉送交換。

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.

在儲存轉送交換器中，每個訊息在傳送到目的地之前都會被接收並儲存在緩衝區中。這消除了碰撞檢測的需要，從而實現了更高的速度並消除了共享介質的需要。

The Birth of the Learning Bridge

學習橋的誕生

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.

肯普夫的想法是在與軟體工程師鮑勃·謝利 (Bob Shelly) 的合作中形成的。他們共同開發了「學習橋」的概念，這是一種連接多個乙太網路 LAN 並根據封包的目標 MAC 位址選擇性地轉送封包的裝置。

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.

學習橋有幾個優點。它允許輕鬆升級現有乙太網路，將大量流量隔離到特定網段，並將有效電纜長度限制加倍。最重要的是，它消除了共享媒體存取協定固有的效能瓶頸。

Overcoming Obstacles and Gaining Acceptance

克服障礙並獲得認可

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.

肯普夫的創新面臨多項挑戰。其中之一是封包在配置錯誤的網路中無限循環的風險。然而，另一位 DEC 工程師 Radia Perlman 提供了一個解決方案：生成樹協議，它可以確保網橋形成樹狀拓撲，防止環路。

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.

另一個挑戰是需要高效能硬體以線速處理資料包。 Kempf 使用可程式陣列邏輯 (PAL) 裝置設計了客製化硬體引擎，以實現所需的效能。

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.

儘管面臨這些挑戰，Kempf 的電橋技術仍具有開創性。 1986 年，DEC 推出了 LANBridge 100，這是第一款商用學習橋。它允許現有的基於 CSMA/CD 同軸電纜的乙太網路升級到更高的速度。

The Gradual Migration to Switched Ethernet

逐步遷移到交換以太網

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 的橋接技術並沒有取代以太網，而是對其進行了補充。透過允許現有乙太網路之間的儲存轉送交換，網橋為從同軸電纜上的CSMA/CD 逐步遷移到單一電腦和專用交換器連接埠之間現在無處不在的銅纜和光纖鏈路鋪平了道路。

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.

鏈結的速度不再受到碰撞檢測的限制。隨著時間的推移，這項變革徹底改變了人們對乙太網路的看法。

The Impact of Switching Technology

交換技術的影響

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.

效能越來越高的網橋的存在有效地使新的共享媒體 LAN 存取協定變得過時。後來，面對更快的乙太網路版本，FDDI 從市場上消失了。

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.

橋接技術還促進了更高級網路功能的開發，例如虛擬 LAN (VLAN) 和對多種網路協定的支援。這些增強功能進一步促進了乙太網路的壽命和普及。

The Lasting Legacy of Mark Kempf

馬克肯普夫的持久遺產

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.

肯普夫發明的學習橋在乙太網路的發展過程中發揮了關鍵作用。它將乙太網路從共享媒體技術轉變為交換網絡，為我們今天使用的高速、可靠和高效的網路鋪平了道路。

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.

肯普夫的貢獻尚未得到應有的廣泛認可。然而，他的發明對互聯網和整個數位領域的發展產生了深遠的影響。

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.

乙太網路的持久成功證明了創新的力量和馬克·肯普夫等工程師的遠見。在我們慶祝成立 50 週年之際，重要的是要記住那些塑造了其歷史並繼續推動其發展的無名英雄。