美國斯坦福大學(Stanford University)工程教授 Nick McKeown 預期，未來十年將有一個新品種網(wǎng)絡處理器取代目前路由器與交換器中使用的ASIC；他表示他已經(jīng)深入研究過該種未來的通訊處理器：“而如果你努力瞇著眼睛看，它就像是網(wǎng)絡的RISC處理器?！? McKeown協(xié)助推動以 OpenFlow 通訊協(xié)議為基礎的軟件定義網(wǎng)絡，其目標是催生一系列全新的軟件應用程序，以管理各種簡化的交換器與路由器。如果他的任務成功，將可讓營運大型資料中心與企業(yè)網(wǎng)絡更為簡單且成本更低，并可望顛覆目前采用復雜ASIC與專屬程序代碼、成本高昂的網(wǎng)絡設備業(yè)務模式。 McKeown所預期的新品種商用芯片，將可取代目前包括Alcatel-Lucent、Cisco、 Ericsson、Juniper等大廠的ASIC方案；他表示，首批該類新芯片將會在接下來2~3年問世。 透 過與TI等廠商的合作，McKeown以論文形式完成了新品種組件的原型制作；它基本上包含用以轉譯每個資料封包中不斷增加的各種標頭(header)之 解析引擎(parsing engine)，然后將封包推進一個與標頭內(nèi)圖形匹配的執(zhí)行單元(execution unit)流水線，并使其動作(action)。 “這是一個強制性的匹配-動作、匹配-動作前饋流水線(feed-forward pipe)；”McKeown表示，其相關研究論文正在進行發(fā)表前的審查。 根據(jù)McKeown的論文，只要增加15%的芯片面積與功耗，該新型芯片就能以與目前僅支持特定通訊協(xié)議的ASIC之相同性能水準，處理今日或未來的任何一種通訊協(xié)議。他預期，那些大型路由器與交換器業(yè)者，在十年之內(nèi)就會以該類芯片取代他們的ASIC，并轉型為軟件公司。 “我 們在十年內(nèi)就能看到成果，那些廠商將會在最上層提供控制平面軟件(control plane software)與應用程序?！彼赋觯呀?jīng)有兩、三家業(yè)者在研究開發(fā)該類芯片，包括新創(chuàng)公司xPliant，以及TI或可能Cavium、 Mellanox 這類老牌公司。 “商用芯片會是OpenFlow計劃的主要推動力之一；”McKeown表示：“現(xiàn)有芯片供貨商包括Broadcom與Marvell的交換器芯片都已經(jīng)準備加入對OpenFlow的支持──這是他們應該做的，而且他們從一開始就有參與?！? 本文授權編譯自EE Times，版權所有，謝絕轉載 本文下一頁：技術的演進將會推動產(chǎn)業(yè)的革命

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{pagination} 隨著新一代軟件與硬件的誕生，技術的演進將會推動產(chǎn)業(yè)的革命。目前1.x版本的OpenFlow代表著一種妥協(xié)，McKeown指出：“理想上我們將讓它以 一種通用的匹配-動作工作流程來開始，但也得讓它映像(map)到現(xiàn)有的芯片上──下一代的技術將會是更不仰賴特定協(xié)議?！? 去年，負責監(jiān)管OpenFlow協(xié)議的開放網(wǎng)絡基金會(Open Networking Foundation，ONF)，忙著邀集ASIC供貨商成立Forwarding Abstractions工作小組；該工作小組的宗旨是將OpenFlow希望達成的目標與現(xiàn)有、計劃中ASIC的目標之間的鴻溝縮小。 現(xiàn)在，ONF正展開“芯片顧問委員會(chip advisory board)”的成立工作；McKeown表示：“我們將向他們學習芯片技術的可能性，從那里可以衍伸出下一代OpenFlow的可能性?！? OpenFlow 已開始采用內(nèi)容可尋址內(nèi)存(content-addressable memories)作為路由器與交換器ASIC的中間媒介，不過這種方法的功能有限制；因此最近該標準開始使用一種匹配多重窗體(matching multiple tables)技術。McKeown表示：“不僅支持單一種協(xié)議的OpenFlow版本還要好一段時間才會誕生?！? 在 軟件部分，催生軟件定義網(wǎng)絡(SDN)的程序代碼也陸續(xù)誕生中；新創(chuàng)公司包括Big Switch Networks與已經(jīng)被VMWare收購的Nicira，都已經(jīng)有它們的OpenFlow控制器軟件。在本月稍早，有18家大型通訊設備業(yè)者與軟件供應 商宣布合作推動一項Open Daylight計劃，旨在為SDN控制器、相關應用程序接口(API)等建立開放源碼環(huán)境。 產(chǎn)業(yè)觀察家預期，各大廠將爭相讓自家程序代碼成為Open Daylight計劃的一部分；一旦市場上出現(xiàn)夠可靠的產(chǎn)品，IBM這類大型業(yè)者將會愿意花錢采用，藉以提供整合型服務──不過恐怕要等到兩三年之后。 McKeown以一種后來變成Linux的API標準集Posix為比喻；他指出，該種有不同版本的操作系統(tǒng)花了十年的時間才安定下來到某個讓Posix應用程序接口能被撰寫出來的階段，同樣的情況可能也會發(fā)生在SDN的應用程序接口上。 本文授權編譯自EE Times，版權所有，謝絕轉載 編譯：Judith Cheng 參考英文原文：Will ASICs be replaced in comms gear?，by Rick Merritt

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{pagination} Will ASICs be replaced in comms gear? Rick Merritt Stanford’s Nick McKeown sees a new breed of merchant networking processors replacing ASICs in routers and switches over the next decade SAN JOSE, Calif. – Nick McKeown, an engineering professor at Stanford University, expects a new breed of merchant networking processors to replace ASICs in routers and switches over the next decade. McKeown says he has looked into the future of communication processors “and if you squint hard it looks like RISC for networking.” McKeown helped kick start the movement toward software-defined networking based on the OpenFlow protocol. Its goal is to enable a new class of software apps that manage gangs of simplified switches and routers. If the effort succeeds it could ease and lower the cost of running large data centers and business networks. It will also disrupt the current business model based on expensive network gear that uses complex ASICs and proprietary code. McKeown sees a new breed of merchant chips taking the place of the big ASICs companies such as Alcatel-Lucent, Cisco, Ericsson, Juniper and others design today. The first attempts at creating them likely will emerge over the next two or three years, he said. In a research effort with Texas Instruments and others, McKeown created a prototype on paper of the new device. It essentially consists of a parsing engine that interprets the increasingly wide set of headers on each packet then pushes the packet into a pipeline of execution units that match patterns in the headers and take actions on them. “It’s a brute force feed-forward pipe of match and action, match and action,” he said, relating work in a paper now under review for publication. The paper reports that for 15 percent more silicon area and power such a chip could handle any current or future protocol at the same performance levels as today’s protocol-specific ASICs. McKeown predicts that in a decade the big router and switch players will have replaced their ASICs with such merchant chips and morphed into software companies. “We’ll look back in 10 years and they will be providing control plane software and apps on top of it,” he said. Two or three companies are said to be exploring such chips already including startup xPliant and existing players such as TI and possibly Cavium and Mellanox. “Merchant silicon is one of the prime drivers of this movement,” said McKeown. “The incumbent chip vendors such as Broadcom and Marvell are adding OpenFlow support to their switches already--that’s what they should do, and they have been involved from the start,” he said. A chicken-and-egg dance It will be revolution by evolution as the new software and new hardware emerge in a chicken-and-egg dance. The current 1.x versions of OpenFlow represent a compromise. “Ideally we would have started it as a generic match-and-action flow, but it had to be mapped on to existing chips—the next generation will be more protocol independent,” McKeown said. Last year, the Open Networking Foundation (ONF) that oversees OpenFlow engaged ASIC makers in a so-called Forwarding Abstractions working group. It aimed to narrow the gulf between what OpenFlow wants to enable and what existing and planned ASIC do. Now ONF is starting a new effort it calls a chip advisory board. “We will learn from them what’s possible [in silicon], and out of that will emerge what’s possible for the next generation of OpenFlow,” he said OpenFlow began using content-addressable memories as an intermediary to interface to router and switch ASICs, but the approach limited its functionality. More recently it has used a technique of matching multiple tables. “The protocol independent version [of OpenFlow] will take awhile,” McKeown said. An evolving software stack On the software side, the pieces of the code to enable software-defined networks are still emerging as are the people who will write it. Startups including Big Switch Networks and Nicira, now part of VMWare, already have their own versions of OpenFlow controllers. Earlier this month, eighteen large comms and software vendors launched Open Daylight, an effort to create open source code for SDN controllers, the APIs for apps that ride on it and maybe more. Observers expect the giants to jostle over whose code becomes part of Open Daylight. If a solid product emerges they say companies such as IBM will make money selling integration and services using it—but that could be two or three years away. McKeown uses the metaphor of Posix, a standard set of APIs for what became Linux. It took a decade for the various flavors of the operating system to settle down to a stage that the Posix APIs could be written. The same may be true for the APIs the enable software-defined networking, he said.