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IVE 'EM WHAT THEY WANT, when they want it.The strategy for serving up Web content reallyis that simple: Customers expect their pagesimmediately, and if they don't see them that soonthey'll waste no time searching elsewhere. Trouble
is, speedy delivery over today's sluggish InternetlinkS is a tall order. And every frustrated surfer whocuts to another site is another potential customer lost.
ANG ELA M. PUG H is associate editor, WAN services for Data Communications and is based in
New York. She can he reached at [email protected].
PHOTOGRAPH: HAROLD & ESTHER EDGERTON FOUNDATION, 1999, COURTESY OF PALM PRESS, INC.
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Service
AderoworldCircle No. 471
Provider
Adero Inc.Cambridge, Mass., 617-868-1886www.aderocom
FreetlowCirde No. 472
Akamai Technologies Inc.Cambridge, Mass., 617-250-3000www.akamai.com
Sandpiper Networks Inc. FootprintThousand Oaks, Calif., 805-370-2100 Circle No. 473www.sandpiper.net
25 countries: Austra1ia, Brazil, Canada, Denmark,Egypt, France, Germany, Hong Kong, Hungary,India, Ireland, Israel, Kenya, Korea, Malaysia,the Netherlands; New Zealand, Poland, Singapore,South Africa, Spain, Sri Lanka, Sweden,Switzerland, u.S.7 countries: Austra1ia, Brazil, Germany, HongKong, Japan, U.K., U.S.
RAID = &dlmdant array of inJependmt discs
32 .DATA COMMUNICATIONS. www.data.com PHOTOGRAPH BY ANN STATES/SABA
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on how many ISP backbones). Pore over the architectural de-tails too; find out just how the agents, probes, and caching andmirroring features work to boost performance. Also ask the ob-vious question: Just what kind of content does the providerhandle? Look into the servers, too, and check whether the pro-vider changes URLs to affect customers' brand identity. Re-member that the availability of service-level agreements (SLAs)and the pricing specifics can playa big part in the fmal decision.
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TABLE OF CONTENTAside from Akamai, Adero Inc. (Cambridge, Mass.) and Sand-piper NetWorks Inc. (Thousand Oaks, Calif.) are now sellingcontent delivery services (see Table I). If statistics are to bebelieved, their timing is right. A survey conducted by researchfirm Jupiter CommunicationsLLC (New York) showed that 47percent of end-users who experience technical problems thefirst time they try connecting to a Web site will simply go toanother-and 9 percent of that number will never return.
The three providers have several things in common. First,they can deliver content to users in real time. Second, they fur-nish logs and traffic statistics. Third, they offer online monitor-ing via Web-based G UIs and allow customers to keep ~bs on .
the CDN. Finally, they allow customers to update content di-rectly and at will, rather than forcing them to schedule updates.
But that's about where the similarity ends. Geographic.coverage, for one thing, varies. Akamai claims coverage in 25countries, Adero in 19, and Sandpiper in 7. Akamai plans to bein 30 countries by the end of the year, and Sandpiper in 15.
Adero, which is hoping to expand to 30 countries, says it'sfocusing on the international market-either u.S. companiesthat have large amounts of traffic from overseas, or interna-tional companies that have a lot of Web traffic from the u.S.Why? The need for content delivery services is more pressing
.outside the U.S., according to Oliver Jones, vice president of
.,. engineering for Adero. u.S. netWorks are "hyperconnnected,"" meaning there are many routes from a Web server to an end-
user. But internationally, the 'Net is more hierarchical, Jonessays, and performance is lower. Adero thinks it can give thosecustomers a 20 percent to 300 percent performance increase.
cate their servers. Akamai is in the lead on this front, claiming1,200 servers on25 networks-with plans for "thousands" ofservers on 60 networks. Sandpiper claims 800 servers on 25networks, with plans to expand to 1,000 servers on 30. Aderohas 25 servers on 25 networks, with plans for 40 on 40 by theend of the year.
There's more to keep in mind. Potential customersshould also take into account the number of other customersa provider has. The more there are, the greater the number ofusers sharing the network. Akamai claims to have 40 corpo-rate customers; Sandpiper, 25; and Adero, 12.
1 costs.
~ctUral de-lching andlSk theob-~ provider~r the pro-mtity. Re-nts 1~',As)d dt ion.
DELIVERY DETAILSof course, coverage and servers are only part of the picture.Net architects would also be wise to learn exactly what theseprovige'rs do--and how they do it.
Akamai and Sandpiper offer tWo delivery options: deliv-ery of all Cllstomer content, or delivery of just the band-width-intensive material like graphics. (Customers deliverthe "lighter" text portion from their own Web servers.)Adero delivers all content.
So how do those options work in practice? Say a user isdownloading content from the Web site of a company thatdelivers its own text but leaves the graphics to a CD N operator(see Figure 1). The user's browser locates the company site bysending a request to the local DNS (domain name service)server, which returns the IP address of the site and transpar-ently makes the connection-just as with any ordinary Webrequest. When the user reaches the company Web site, the textportion of the content is delivered-but the browser is alsoredirected to a CDN, which delivers the nontext data.
It's worth noting that even when Akamai is delivering thefull mix of text and graphics, the Web request is still routed viaits customer's web server. But Adero and Sandpiper go about
SERVER SETUPBut geographic coverage is only one factor. Net architectsalso should find out on how many networks providers colo-
~;'~;,~;;,..it'tI
RewritesQJStDmer URLto affect brandidentityNo
~jflielary,peaive
Cache
lnktomiTrafficServer
Mirroring Type of serversYes Solaris 250 servers(Webspective) with dual 360-MHz
processors,IGbyteRAM, and 100 Gbytesof RAID storage
Proprietary No Intel-based serverssofrware with dual Pemiwn ill
processors and1 GbyteRAM(notcunently usingstorage)
Yes Sun Ultra II servers(proprietary with dual 300 MHzsofrware) processors,IGbyte
RAM, and over60 Gbytes of RAIDstorage
Service-level agreementsUptime and fe5ponse time(details not available at press time)
Monthly cost
$1,99510$3,195 perMbir/ S (depending onregion); $200 to $345per region
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Downloadable media,
.dynamic content,'..; grnphics, software!:&i downloads, streaming
media, text
AUthenticated content,dOWnloadable media, .
dyT.arnic content,graphics, softwaredownloads, streaming~~textAuthenticated content,
..downloadable media,
dynamic content,grnphics, softwaredownloads, streamingmedia, teXt
Yes 100 percent uptime; content delivery using $1,995 per Mbit/ s withFreeJloW will be faster than cusromers volume discountScould deliver it themselves
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TrafficServer
No 100 pen:ent uptime; content delivery using $2,000 per Mbit/ 5 WidtFootprint will be faster than cusromeB volume discountScould deliver it dtemselves; old contentwill never be served; customeB Will begiven daily traffic logs; CUStOmeB canmonitor activity on dte Footprint netWOrk
)11-.,'\TES/SARA DATA COMMUNICATIONS. OCTOBER 21, 1999 .33
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CONTENT DELIVERY NETWORKS--~
Software AuthenticatedProvider Service Text Graphics Downloadable media Streaming media downloads contentAdero Aderoworld HTML, AI, EPS, GIF, Jpeg, AIFF, AU, Midi, MP3, Quicklime, Real, RTSP, FTP, HTTP No
TXT PDF, PNG, Tiff Mpeg, Shockwave, Wav Vivo
Akamai Freeflow HTML, .M,EPS, GIF, Jpeg, AIFF; AU, AVI, MP3, Quicklime, Reai,RTSP, FTP,HTTP Cookies, digi1alcerrificates,TXT PDF,PNG,Tiff Mpeg, Shockwave, Wav Windows MediaPla~ passwords
Sandpiper Footprint HTML, AI, EPS, GIF, Jpeg, AIFF, AU, AVI, MP3, Quickrime, Real, RTSP, FTP, HTTP Cookies, digi1alcertificates,TXT PDF, PNG, Tiff Mpeg, Shockwave, Wav Wmdows Media Player passwords
FTP = File transfer protocol H1TP = Hypertext "-fer protocol Midi = Musical instntment digital interface Tiff = Tagged image file fonnatHTML = Hypertext markup language Jpeg = Joint plratograplric experu group Mpeg = Motion picture experu group RTSP = Real-time s"eaming protocal
it a bit differently. Yes, the initial request goes to the DNS ]server-but what's returned is the IP address of the server onthe CD N that can deliver the content. The origin server (thatis, the company's) is eliminated altogether, which both compa-nies claim augments performance.
PROBING QUESTIONSNext up in the content delivery decision process aretbe spe-cific methods providers use to improve performance oncerequests have reached the CDN.
All three say they use proprietary softWare algorithms-running either on server agents or standalone probes-toroute incoming requests for content over the most efficient
path on the Internet, and to the server that is best able to han-dle them. (Probes sit on such ISP devices as routers, whileagents typically reside on servers.)
Their algorithms base their routing decisions on threetypes of information. First, they measure the load and avail-ability of their own servers. Second, they measure the geo-graphical proximity of users to the available servers in theCDN. Third, they monitor the'Net for congestion and out-ages, using that data to build a weather map of performance."You need probes' on ISPs outside of your own network togain a more realistic view of real performance on the Inter-net,"says Leo Spiegel, CEO_of Sandpiper.
Adero uses both probes and agents to gather informa-tion. Its 25 probes use dial-up accountsto measure response times for end-users; its agents gather information onsuch metrics as latency, as well as dataculled from public databases that gatherstats on the Internet, to form its map.
Sandpiper's probes do the samething by gathering data on about 25variables, ranging from packet loss andlatency to static network topology andpeering relationships. Akamai calls itsagents "monitors," and says they gatherdata on the performance of the publicInternet as well as the performance of
~ its own network. Akamai claims to havemonitors on all 1,200 of its servers.Sandpiper has 150 probes. Adero has 25probes and 25 agents.
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publishers so they can see howpeople are requesting their sites.
Many ISPs cache content,Joe Laszlo, : ~ ".
held perception otsatelliteiechnology as something that just hasn't proven itself."The industry hasn't embraced satellite [as a transport medium] yet," admitsRanguSal~me, president and chiefex~UtiV~ of Edgix. But he's hopeful, assertingh h O Mt at'ullslSC anglng:'-A. .P.':,'.'- ,
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34 .DATA COMMUNICATIONS. www.data.com
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StlAAPaten1the CJAdero uses a mirroring product from Webspective Soft-
ware Inc. (Needham, Mass.), while Sandpiper uses propri-etary algorithms (and says it will look into a possible partner-ship with a mirroring vendor in the future). Akamai doesn'toffer mirroring, saying it hasn't seen huge demand-but itnonetheless is considering supporting it later this year.
TALATES
THE CHARACTER OF THEIR CONTENTof course, the best performance in the world means nothing ifa provider doesn't handle the specific types of content a cus-tomer has. While all deliver graphics, downloadable media,streaming media, software downloads, and text, there aresome distinctions to make (see Table 2). Sandpiper and Aka-mai, for example, can both deliver authenticated content-including cookies, digital certificates, and password-protectedsites. Adero doesn't, but says it has plans to do so.
None of the vendors can process e-commerce transac-tions. They can deliver images for catalogs, but when it comesto making a credit card ttansaction, the end-user has to gothrough the Web site owner's transaction server. "They canbrowse arid do everything until checkout," says Adero's Jones."Then they would go to a transaction server."
So what's the problem? Actually, there are tWo. The flrsthas to do with se~ty: In order to process a transaction, aserver needs an authentication key, and that key would have tobe distributed to all of a content delivery provider's servers.
The second has to do with the customer's fmancial appli-cations (including billing and payment apps). In order fore-commerce transactions to be processed on multiple CDNservers, the apps would have to be running on all of the
"is a problem. Control of the content is taken out of the con-tent publisher's hands. They want everyone to get the samepicture, and with some ISP caches, it's unclear how often a siteis updated," he says. In addition, companies have no way to seehow many people have looked at their sites, information that'simportant when setting advertising rates.
But all of the content delivery providers say they canupdate content in real-time--so only the freshest content isserved. They do so by looking at traffic logs from inside theISP caches via proprietary algorithms. Adero says its cachesand ISP caches can be configured as peers, talking to eachother via I CP (Internet caching protocol).
With Akan1ai and Sandpiper, the ISP caches essentiallybecome part of the content delivery netWork. The caches cantalk to each other via proprietary software. This integration ben-efits the CDN provider, the ISP, the Web site owner, and theend-user. CD N providers can update content for their customersin the ISP cache and can offer them hit statistics. The ISP bene-fits because it doesn't have to go all the way back to the originserver to update content (saving money on bandwidth). TheWeb site owner doesn't have to worry that old content is in ISPcaches, and end-users get the content faster. Adero and Sand-
per use Traffic Server from Inktomi Corp. (San Mateo,Calif.) for caching, while Akarnai uses its proprietary algo-rithms. "It costs less because it was developed internally," saysKieran Taylor, senior product manager for Akan1ai.
Net architects may also want to look into mirroring,which allows providers to send copies of content to multipleservers on their networks. They typically use mirroring topush content if it's popular or frequently requested.
36 .DATA COMMUNICATIONS. www.data.com~
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machines. According to Sandpiper, e-commerce softWare cur-rently runs on the back-end of networkS. He says that mas-sively distributed databases need to come into existence beforee-commerce transaCtions can be processed on CDNs.
That lack of support for e-commerce looms as a realdrawback, according to some observers. "It's nice to serve pic-tures, but at some point it will be equally important to supportthe business that supports the site," says Peter Christy, princi-pal analyst with Collaborative Research (Los Altos, Calif.).
Sandpiper and Adero say that over the long term, theywill focus on processing e-commerce transactions. Akamaidoesn't have the same aspirations. "We're not in the business..of transaCtion processing," says Akamai's Taylor. "We're inthe business of content delivery."
Even though their services can't process e-commercetransactions, Adero and Sandpiper say they can deliver formsfor interaCtive Web polls and time-sensitive information, suchas stock quotes. Akamai says it doesn't deliver stock quotes orinteractive polls because they're largely based on HTML(hypertext markup language )-which Akamai doesn't deliverfor many of its customers.. However, it says it could deliver agraphic display, such as a pie chart, with the poll results.
delivering speedy performance-and dedicated servers arefaster than shared. Trouble is, all three use shared servers.
Another important issue in choosing a content deliveryservice is whether the provider rewrites, or changes, Web siteURLs to affect the company's brand identity. This is a concernfor companies that don't want-end users to see the contentdelivery provider's name when they're viewing a Web page.For instance, sayan end-user is looking at the Web site of aAkamai customer; the URLs of the images will say "aka-maitech.net." If the images are delivered by Sandpiper orAdero, the end-user doesn't see the provider's name anywhere,since their customers give them partial control of their DNSs.
Akamai says it hasn't sensed that URL renaming is an is-sue-but at least one of its customers has. "We forced them tonot chagge it to 'Akamaitech,' " says CNN Internet's Mullig.
~
PROVIDER PROMISESGiven that one of the main benefits of content delivery ser-vices is better performance, net architects might be interestedin just what providers do to back up their promises. Fortu-nately, all three vendors offer SLAs. Both Sandpiper and Aka-mai guarantee 100 percent uptime. If the guarantee is not met,the customer is given one day's credit. In addition, both thoseproviders guarantee that they can deliver content with theirservices faster than customers can deliver it themselves.
Sandpiper's SLAs address three other areas as well. First,
,orateI server
SHARED PROBLEMS?, Potential customers also need to know what types of servers~.' the CDNs are using. Fast servers are an important part ofve Soft-
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DATA COMM DOES.TAKE OUR ONLINE, ,INTERACTIVE POLL AND LET US KNOW YOUR OPINION ABOUT THE
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ARE REALLY THINKING. JUST POINT YOUR WEB BROWSER AT \~!W\V.I)Al/\.(:()MAND CLICK ON THE INTERACTIVE POLL ICON.
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This way, a customer can utilize the volume discount and becharged a lower rate per Mbit/ s if its traffic level has increased.
the provider guarantees that it will never serve old content.Second, it promises customers that they will receive daily traf-fic logs. Third, Sandpiper guarantees that corporate customersalways will be able to monitor the activity on its Footprint net-work. If any of the SLAs are not met, the customer receives aone-day service credit.
So where is Adero on the SLA front? It offers them foruptime and response time, but it didn't have any other detailswhen this issue went to press.
DELIVERY DOWNSIDEWhile CDN services may give net architects hope of betterperformance and cheaper bandwidth, there are a few prob-lems to keep in mind. While all three providers want toexpand coverage by entering as many ISP networks as possi-ble, right now they're not really in all that many. And thatmeans some end-users might be out of reach of a specific net-work-in which case they'll receive their content only fromtl1e nearest available server.
And while there's no doubt the services offer speedier con-tent delivery, observers aren't so sure about how much of amarket there can really be. "There seems to be a built-in limit tohow much they can grow," says Jupiter's Laszlo. "Once theyget past the top 20 or 50 Web sites, the value proposition to aweb site will be less clear. They need to make themselves at-tractive to smaller Web ventures." This is because traffic costsincrease dramatically once a site goes above a certain threshold."0 On top of that, the architecture of the public Internetmight even place limits on just how good performance can be.That's why S()me of the providers are looking to add satellitedelivery intlle future, which would bypass the public Internetaltogetl1er (see "The Space Case"). But "future" is the keyword here: Right now, none of them offer satellite delivery.
Nevertheless, proximity plays a major role in both per-formance and price-and that's the big benefit of contentdelivery services these providers are trumpeting. "If you canget content from a location closer to you, performance isalmost always faster, and usually cheaper," says Christy ofCollaborative Research. ~
Read
up on content delivery networks (CONs) and relatedtopics. Check out these URLs:
.www.caching.com The Web site for collaborative Research,an analyst firm specializing in e-commerce and e-businessinfrastructure, features papers on CD N s and satellite services, aswell as information on caching..wwwJup.com click here for ~e web site of research firm JupiterCommunications LLC (New York). Visitors can view reportson such topics as content hosting, online commerce, and whatconsumers want from a Web site..isp-lists.com/isp-caching This list contains information thatcan help net architects get up to speed on the types of caching ISPsare using-ranging from Squid and proxy server solutions to newsatellite caching systems..www.inktomi.com/products/traffic Net architects can visit thissite for the specifics on Inktomi's Traffic Server, which two ofthe three CDNs use. It also features the Traffic Server BandwidthCalculator, which shows net architects how much bandwidth theycan save by caching content on their networks.
THE COST OF CONTENTThe bottom line is a big part of the decision-making process fornet architects. That's why it's important to understand the pric-ing schemes for content delivery services.
Start with Sandpiper, which charges $2,000 per Mbit/ s permonth. Akamai charges $1,995 per Mbit/s per month. Bothoffer volume discounts. Adero, on the other hand, offers twotypes of pricing. In the first scheme, it charges per Mbit/ s; inthe second, it charges per region served. Bandwidth-based pric-ing ranges from $1,995 to $3,195 per Mbit/s per month, de-pending on the region served. Region-specific pricing rangesfrom $200 to $345 per month. The $200 per-region price in-cludes delivery of 5,000 page views a day and 50 Mbytes ofdownloads per day for one region. In this model, Web site own-ers can decide which regions they want to use the service for,and Adero will serve the content to those areas only.
All the providers base their bandwidth pricing on the 95thpercentile model. Here's what that means. Every 5 minutes (inthe c,ase of Sandpiper) or 12 minutes (in the case of Akamai),the provider gathers statistics on how much traffic is movingover its network for each of its customers. All of the samplesare compiled, and the top 5 percent are thrown out. The cus.-tomer's monthly charge is based on the next -number, Vfhich is at the 95th percentile mark.
N eei an example? Say Acme Corp. isusing AKamai's network to deliver content.Every 12 minutes, each of Akamai's serversmeasures how much of Acme's traffic is travel-ing over its network. All of those stats are fedback to a central location. At the end of themonth, all of the measurements are put indescending order (10 Mbit/s; 9 Mbit/s, 8Mbit/ s, 7. Mbit/ s, etc.). The top 5 percent areerased, and the company is charged based onthe next number, say 5 Mbit/ s.
All customers using this pricing schemesign up for a certain committed aggregate in-formation rate (CAIR), which is a guaranteeddata rate they will use each month. For instance,if a company signs up for a 10 Mbit/ s CAIR, itcommits to that level of traffic and is chargedbased on that number. All of the vendors letcustomers burst over their CAIR levels.
All three vendors also give customers theoption of increasing their CAIR on a daily basis.
38 .DATA COMMUNICATIONS. www.data.com
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