(12) United States Patent
`Leighton et a1.
`
`(10) Patent N0.:
`(45) Date of Patent:
`
`US 7,693,959 B2
`Apr. 6, 2010
`
`US007693959B2
`
`(54)
`
`(75)
`
`(73)
`
`(*)
`
`(21)
`(22)
`(65)
`
`(63)
`
`CONTENT DISTRIBUTION SYSTEM USING
`AN ALTERNATIVE DOMAIN NAME SYSTEM
`(DNS) AND CONTENT SERVERS
`
`Inventors: F. Thomson Leighton, Newtonville, MA
`(US); Daniel M. LeWin, Cambridge, MA
`(Us)
`
`Notice:
`
`Assignee: Massachusetts Institute of Technology,
`Cambridge, MA (US)
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 831 days.
`Appl. N0.: 11/515,171
`Filed:
`Sep. 1, 2006
`
`Prior Publication Data
`
`US 2007/0005689 A1
`
`Jan. 4, 2007
`
`Related US. Application Data
`
`Continuation of application No. 10/417,607, ?led on
`Apr. 17, 2003, now Pat. No. 7,103,645, which is a
`continuation of application No. 09/604,878, ?led on
`Jun. 28, 2000, now Pat. No. 6,553,413, which is a
`continuation of application No. 09/314,863, ?led on
`May 19, 1999, now Pat. No. 6,108,703.
`
`(60)
`
`(51)
`
`(52)
`
`(58)
`
`Provisional application No. 60/092,710, ?led on Jul.
`14, 1998.
`
`Int. Cl.
`(2006.01)
`G06F 15/16
`(2006.01)
`G06F 15/173
`US. Cl. ..................... .. 709/217; 709/219; 709/229;
`709/238
`Field of Classi?cation Search ............... .. 709/217,
`709/219, 229, 238
`See application ?le for complete search history.
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`EP
`
`4,922,417 A
`
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`(Continued)
`Primary ExamineriWilliam C Vaughn, Jr.
`Assistant ExamineriKristie D Shingles
`(74) Attorney, Agent, or FirmiDavid H. Judson
`
`ABSTRACT
`
`(57)
`The present invention is a network architecture or framework
`that supports ho sting and content distribution on a truly global
`scale. The inventive framework allows a Content Provider to
`replicate and serve its most popular content at an unlimited
`number of points throughout the world. The inventive frame
`work comprises a set of servers operating in a distributed
`manner. The actual content to be served is preferably sup
`ported on a set of hosting servers (sometimes referred to as
`ghost servers). This content comprises HTML page objects
`that, conventionally, are served from a Content Provider site.
`In accordance with the invention, however, a base HTML
`document portion of a Web page is served from the Content
`Provider’s site while one or more embedded objects for the
`page are served from the hosting servers, preferably, those
`hosting servers near the client machine. By serving the base
`HTML document from the Content Provider’s site, the Con
`tent Provider maintains control over the content.
`
`58 Claims, 2 Drawing Sheets
`
`1
`
`Petitioner Limelight - LN1001
`
`

`
`US 7,693,959 B2
`Page 2
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`
`2
`
`

`
`US 7,693,959 B2
`Page 3
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`3
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`Malkin, “RIP Version 2,” Internet Engineering Task Force (IETF)
`Request for Comments (RFC) 2453, Nov. 1998.
`Deering et al, “Internet Protocol, Version 6 (IPv6) Speci?cation,”
`Internet Engineering Task Force (IETF) Request for Comments
`(RFC) 2460, Dec. 1998.
`Narten et al., “Neighbor Discovery for IP Version 6 (IPv6),” Internet
`Engineering Task Force (IETF) Request for Comments (RFC) 246 1,
`Dec. 1998.
`Eastlake et al, “Domain Name System Security Enhancements,”
`Internet Engineering Task Force (IETF) Request for Comments
`(RFC) 2535, Mar. 1999.
`* cited by examiner
`
`4
`
`

`
`US. Patent
`
`Apr. 6, 2010
`
`Sheet 1 of2
`
`US 7,693,959 B2
`
`1 4
`
`SERVER
`
`PROCESSOR /18
`
`OS
`
`20
`
`WEB SERVER
`
`22
`
`API
`
`\26
`
`L28
`
`FIG. 7
`
`F I G. 2
`
`39
`{:1
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`
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`US
`50
`
`CONTENT
`
`may J £0
`HOST I
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`DNS
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`LEVEL
`
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`LEVEL
`HOST
`38
`36/
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`é’???gii?ié
`
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`
`x
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`X
`
`FIG. 3 42
`
`36/ HOST
`
`36/ HOST
`
`36/ HOST
`
`HOST
`
`55
`
`5
`
`

`
`US. Patent
`
`Apr. 6, 2010
`
`Sheet 2 of2
`
`US 7,693,959 B2
`
`F I G. 4
`
`GET NEXT OBJECT K52
`‘
`[HASH VALUE INPUT
`PREPEND VIRTUAL [54
`SERVER HOST NAME
`‘
`PREPEND HASH
`VALUE AS FINGERPRINT \56
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`
`[HASH VALUE INPUT
`
`"TOP LEVEL"
`DNS SERVER
`
`NEARBY
`GHOST
`
`"LOW LEVEL"
`DNS SERVER
`
`6
`
`

`
`US 7,693,959 B2
`
`1
`CONTENT DISTRIBUTION SYSTEM USING
`AN ALTERNATIVE DOMAIN NAME SYSTEM
`(DNS) AND CONTENT SERVERS
`
`CROSS-REFERENCE TO RELATED
`APPLICATIONS
`
`This application is a continuation of prior application Ser.
`No. 10/417,607, ?ledApr. 17, 2003, now US. Pat. No. 7,103,
`645, Which application Was a continuation of prior applica
`tion Ser. No. 09/604,878, ?led Jun. 28, 2000, now US. Pat.
`No. 6,553,413, Which application Was a continuation of prior
`application Ser. No. 09/314,863, ?led May 19, 1999, now
`US. Pat. No. 6,108,703, Which application Was based on and
`claimed priority from Provisional Application 60/092,710,
`?led Jul. 14, 1998.
`
`BACKGROUND OF THE INVENTION
`
`1. Technical Field
`This invention relates generally to information retrieval in
`a computer network. More particularly, the invention relates
`to a novel method of hosting and distributing content on the
`Internet that addresses the problems of Internet Service Pro
`viders (ISPs) and Internet Content Providers.
`2. Description of the Related Art
`The World Wide Web is the Intemet’s multimedia infor
`mation retrieval system. In the Web environment, client
`machines effect transactions to Web servers using the Hyper
`text Transfer Protocol (HTTP), Which is a knoWn application
`protocol providing users access to ?les (e.g., text, graphics,
`images, sound, video, etc.) using a standard page description
`language knoWn as Hypertext Markup Language (HTML).
`HTML provides basic document formatting and alloWs the
`developer to specify “links” to other servers and ?les. In the
`Internet paradigm, a netWork path to a server is identi?ed by
`a so-called Uniform Resource Locator (URL) having a spe
`cial syntax for de?ning a netWork connection. Use of an
`HTML-compatible broWser (e.g., Netscape Navigator or
`Microsoft Internet Explorer) at a client machine involves
`speci?cation of a link via the URL. In response, the client
`makes a request to the server identi?ed in the link and, in
`return, receives a document or other object formatted accord
`ing to HTML. A collection of documents supported on a Web
`server is sometimes referred to as a Web site.
`It is Well knoWn in the prior art for a Web site to mirror its
`content at another server. Indeed, at present, the only method
`for a Content Provider to place its content closer to its readers
`is to build copies of its Web site on machines that are located
`at Web hosting farms in different locations domestically and
`internationally. These copies of Web sites are knoWn as mirror
`sites. Unfortunately, mirror sites place unnecessary economic
`and operational burdens on Content Providers, and they do
`not offer economies of scale. Economically, the overall cost
`to a Content Provider With one primary site and one mirror
`site is more than tWice the cost of a single primary site. This
`additional cost is the result of tWo factors: (1) the Content
`Provider must contract With a separate hosting facility for
`each mirror site, and (2) the Content Provider must incur
`additional overhead expenses associated With keeping the
`mirror sites synchronized.
`In an effort to address problems associated With mirroring,
`companies such as Cisco, Resonate, Bright Tiger, F5 Labs
`and Alteon, are developing softWare and hardWare that Will
`help keep mirror sites synchronized and load balanced.
`Although these mechanisms are helpful to the Content Pro
`vider, they fail to address the underlying problem of scalabil
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
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`55
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`60
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`65
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`2
`ity. Even if a Content Provider is Willing to incur the costs
`associated With mirroring, the technology itself Will not scale
`beyond a feW (i.e., less than 10) Web sites.
`In addition to these economic and scalability issues, mir
`roring also entails operational di?iculties . A Content Provider
`that uses a mirror site must not only lease and manage physi
`cal space in distant locations, but it must also buy and main
`tain the softWare or hardWare that synchronizes and load
`balances the sites. Current solutions require Content Provid
`ers to supply personnel, technology and other items necessary
`to maintain multiple Web sites. In summary, mirroring
`requires Content Providers to Waste economic and other
`resources on functions that are not relevant to their core
`business of creating content.
`Moreover, Content Providers also desire to retain control
`of their content. Today, some ISPs are installing caching
`hardWare that interrupts the link betWeen the Content Pro
`vider and the end-user. The effect of such caching can pro
`duce devastating results to the Content Provider, including (1)
`preventing the Content Provider from obtaining accurate hit
`counts on its Web pages (thereby decreasing revenue from
`advertisers), (2) preventing the Content Provider from tailor
`ing content and advertising to speci?c audiences (Which
`severely limits the effectiveness of the Content Provider’s
`Web page), and (3) providing outdated information to its
`customers (Which can lead to a frustrated and angry end user).
`There remains a signi?cant need in the art to provide a
`decentralized hosting solution that enables users to obtain
`Internet content on a more e?icient basis (i.e., Without bur
`dening netWork resources unnecessarily) and that likeWise
`enables the Content Provider to maintain control over its
`content.
`The present invention solves these and other problems
`associated With the prior art.
`
`BRIEF SUMMARY OF THE INVENTION
`
`It is a general object of the present invention to provide a
`computer netWork comprising a large number of Widely
`deployed Internet servers that form an organic, massively
`fault-tolerant infrastructure designed to serve Web content
`e?iciently, effectively, and reliably to end users.
`Another more general object of the present invention is to
`provide a fundamentally neW and better method to distribute
`Web-based content. The inventive architecture provides a
`method for intelligently routing and replicating content over
`a large netWork of distributed servers, preferably With no
`centralized control.
`Another object of the present invention is to provide a
`netWork architecture that moves content close to the user. The
`inventive architecture alloWs Web sites to develop large audi
`ences Without Worrying about building a massive infrastruc
`ture to handle the associated tra?ic.
`Still another object of the present invention is to provide a
`fault-tolerant netWork for distributing Web content. The net
`Work architecture is used to speed-up the delivery of richer
`Web pages, and it alloWs Content Providers With large audi
`ences to serve them reliably and economically, preferably
`from servers located close to end users.
`A further feature of the present invention is the ability to
`distribute and manage content over a large netWork Without
`disrupting the Content Provider’s direct relationship With the
`end user.
`Yet another feature of the present invention is to provide a
`distributed scalable infrastructure for the Internet that shifts
`the burden of Web content distribution from the Content
`
`7
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`

`
`US 7,693,959 B2
`
`3
`Provider to a network of preferably hundreds of ho sting serv
`ers deployed, for example, on a global basis.
`In general, the present invention is a network architecture
`that supports hosting on a truly global scale. The inventive
`framework allows a Content Provider to replicate its most
`popular content at an unlimited number of points throughout
`the world. As an additional feature, the actual content that is
`replicated at any one geographic location is speci?cally tai
`lored to viewers in that location. Moreover, content is auto
`matically sent to the location where it is requested, without
`any effort or overhead on the part of a Content Provider.
`It is thus a more general object of this invention to provide
`a global hosting framework to enable Content Providers to
`retain control of their content.
`The ho sting framework of the present invention comprises
`a set of servers operating in a distributed manner. The actual
`content to be served is preferably supported on a set of hosting
`servers (sometimes referred to as ghost servers). This content
`comprises HTML page objects that, conventionally, are
`served from a Content Provider site. In accordance with the
`invention, however, a base HTML document portion of a Web
`page is served from the Content Provider’s site while one or
`more embedded objects for the page are served from the
`hosting servers, preferably, those hosting servers nearest the
`client machine. By serving the base HTML document from
`the Content Provider’s site, the Content Provider maintains
`control over the content.
`The determination of which hosting server to use to serve a
`given embedded object is effected by other resources in the
`hosting framework. In particular, the framework includes a
`second set of servers (or server resources) that are con?gured
`to provide top level Domain Name Service (DNS). In addi
`tion, the framework also includes a third set of servers (or
`server resources) that are con?gured to provide low level
`DNS functionality. When a client machine issues an HTTP
`request to the Web site for a given Web page, the base HTML
`document is served from the Web site as previously noted.
`Embedded objects for the page preferably are served from
`particular hosting servers identi?ed by the top-and low-level
`DNS servers. To locate the appropriate hosting servers to use,
`the top-level DNS server determines the user’s location in the
`network to identify a given low-level DNS server to respond
`to the request for the embedded object. The top-level DNS
`server then redirects the request to the identi?ed low-level
`DNS server t