OARtech

1. OARtech Patrick W. Gilmore pgilmore@akamai.com, patrick@ianai.net April 11, 2001

2. Agenda Who is Akamai? • Akamai’s Origins & Backgrounds • Content Distribution Network Edge Caches • Akamai Accelerated Network Program • Regions • Buddy System

3. Agenda Content Delivery • Object Delivery • Site Delivery • Video Streaming Mapping • DNS ä'•kuh•my

4. Who Is Akamai?

5. Akamai’s Origins and Background IPO on 10/29 raised $250M 4th best in 1999 • Based in Cambridge, MA • Founded by MIT research team • F. Thomson Leighton, Chief Scientist • Danny Lewin, CTO • Seeded in 1995 as an MIT research effort to improve Internet’s content distribution problem • Team of 1,300 world class professionals • Investors: Apple ($12M), Microsoft ($15M) and Cisco ($49M)

6. Current Akamai Customers

7. What is a Content Distribution Network? Akamai is a Content Distribution Network (CDN) That’s nice, but what is a CDN? • Three main components: • Edge caches • Content delivery • Mapping

8. What is a CDN? Edge Caches • Working with ISPs and networks all over the world to install edge caches • More is better Content Delivery • Getting content to the edge • Includes object, videos, and whole web sites

9. What is a CDN? Mapping • Akamai’s Secret Sauce • Finding the closest edge server for each user • Network proximity, not necessarily the same as geographical proximity

10. How does Akamai’s CDN work? How does a Akamai’s CDN work? • All content must be hosted on an “origin server” accessible to all edge caches • Working on Hierarchy, some customers using now • End users only speak to edge caches, not origin server, to get distributed content • Edge caches pull content once from origin server, then deliver content to many end users

11. How does Akamai’s CDN work? Why is this good? • Allows nearly infinite scalability (if deployed properly) • Good economies at large scales • Avoids congestion and long latency • Speed of light issues, undersea fiber, etc. • Extremely reliable • Mitigates some DoS attacks • Massive redundancy

12. Edge Caches

13. Akamai Accelerated Network Program (AANP) What is the Akamai Accelerated Network Program? • Gives free edge caches to qualified networks • Internet Service Providers • Educational Institutions (usually Universities and K-12) • Government networks • Anyone else with “eyeballs”

14. AANP Benefits Performance • Content served locally, increasing performance Bandwidth Savings • Saves money on upstream, reduces congestion Reliability • A cache on a local LAN is more reliable than a web server on the Internet Interoperability • No routing or DNS changes, already using it today

15. AANP Benefits No Cost – FREE!! • Akamai pays for all equipment, shipping, etc. Easy to implement • Each Cache is just another another host on the LAN Akamai Support • 24 x 7 NOC Co-Marketing • Logo use, press releases, trade shows, etc.

16. “Region” – set of edge caches All Regions • Intel based rack-mount PCs HTTP Regions • Linux based server • Proprietary HTTP server / cache Streaming Regions • Shrink wrapped software installed on our servers • Linux used for QT & Real • Win2K used for WMT

17. Regions Server Configuration • Dual Pentium III processors • Gigabyte of RAM • Two or four SCSI hard drives • Two 100BaseT network cards Additional Hardware • Ethernet switch(es) • 100BaseT or Gigabit ethernet uplinks • Patch Cables

19. Buddy System Each server has two public IP addresses • “Service” address • This is the address given to end users who want to retrieve content • “Physical” address • This is the address used to manage and test the server • If the physical address is not responding, the box is considered to be down

20. Buddy System Server Failure • Servers do fail occasionally • Each server has a “buddy” which is constantly trading hellos with the physical address • When a server stops responding to hellos, its buddy will respond to requests directed at the failed server’s service address • Users in the middle of a download may have to hit “reload” • No one else will notice any interruption

21. Content Delivery

22. Possible bottlenecks on the Internet Last MileProblem First Mile Problem End User Host Server Internet BackboneProblem PeeringProblem

23. Process Flow XYZ 1 1. User wants to download distributed web content

24. Process Flow XYZ 2 1 2. User is directed through Akamai’s dynamic mapping to the “closest” edge cache

25. Process Flow XYZ 2 3 1 3. Edge cache searches local hard drive for content

26. Process Flow XYZ 3a 2 3 1 3a 3b. If requested object is not on local hard drive, edge cache checks other edge caches in same region for object

27. Process Flow XYZ 3b 3a 2 3 1 3a 3b. If requested object is not cached or not fresh, edge cache sends an HTTP GET the origin server

28. Process Flow XYZ 3b 3a 2 3c 3 1 3a 3c. Origin server delivers object to edge cache over optimized connection

29. Process Flow XYZ 3b 3a 2 3c 3 1 3a 4 4. Edge server delivers content to end user

30. The Old Internet

31. The New Internet with Akamai

33. Case Study on Reliability and Scalability: The 2000 Election 22 Crash ZoneWithout Akamai this site could not have served customers abovetheir crash zone 20 17 15 Customer Visits (Millions) 12 10 7 5 2 0 Time

34. How a Non-AkamaizedWebsite Works Customer Web Server End User 1 2 3 4 User enters standard URL Customer’s Web Server returns HTML with embedded URLs User’s browser requests embedded objects from customer Web server Objects served with round trips across the Internet www.customer.com <img src=/images/logo.gif>

35. FreeFlow – Akamai’s Object Delivery Service HTTP request user enters standard URL Client’s Servers HTML code contains Akamai URLs (ARL) HTTP requestfor embedded content Content Served Locally Akamai Server Example ARL: img src= a1000.g.akamai.net/…/www.customer.com/images/logo.gif

36. EdgeSuite – Akamai’s Site Delivery Service Customer CNAME’s (aliases) www.customer.com • Anyone looking up www.customer.com will be redirected to an Akamai hostname - “customer.d4p.net” • No, I do not know why we use “d4p.net”.  • customer.d4p.net is CNAME’d to aXXX.g.akamai.net • Standard Akamai mapping magic sends returns the closest edge server for aXXX.g.akamai.net

37. EdgeSuite – Akamai’s Site Delivery Service End user never communicates with origin server • Akamai retrieves content from private hostname • Something like “origin.customer.com” • High reliability • Thousands of servers backing each other up • If one geographic area is disabled, no other area will be affected • Mitigates some DoS attacks

38. EdgeSuite – Akamai’s Site Delivery Service Uncacheable content is tunneled back to origin • Can reduce need for tunneling with server-side scripts running on edge caches Persistent TCP connections increase performance • Helps with downloading of objects to end caches • Helps with tunneling to origin • (More on this later)

39. Video on Demand Akamai uses HTTP to transit content to edge caches • Allows lossless transport of content to edge • Origin server does not need streaming software, licenses, etc. • HTTP 1.1 byte-range request used to pull only required data User connects to edge cache with streaming protocol • Content is streamed in native format from cache to user • User experience is enhanced through “origin” file available on a “close” server

40. Live Akamai uses UDP to transit content to edge caches • Proprietary reflector network of servers • Akamai translates all streaming formats into UDP • Propagates live stream through reflector network Akamai Streaming Accomplishments: • First 1 Mbps stream live stream fed over public Internet • Single largest streaming event in Internet history • Broke own record 3 times

41. Live “SteadyStream” User connects to edge cache with streaming protocol • Edge cache “subscribes” to reflector network to receive live streaming content • Three streams are delivered to each edge cache • Packet loss is eliminated through redundancy • Content is streamed from edge cache to user

42. X X X X Entry Point Encoding Top-level refelectors 4 4 4 3 Dropped packets don’t degrade stream to regions X Lost connections don’t degrade stream to regions 3 3 2 2 2 X 1 1 1 Regions 4 Akamai SteadyStreamSM technology can deliver streams reliably to the edge with effectively 0% packet loss. 3 2 1 J J J

43. Live Pros: • Allows global distribution of real-time video • Users can connect anywhere and get good video quality over public Internet Cons: • Each region must have 3 users for effective bandwidth use • If streaming rate is > 1/3 access bandwidth to edge cache, congestion will occur • Reflector network uses bandwidth even if no users connect

44. QuickTime Streaming via HTTP Akamai can deliver Apple’s QuickTime files via HTTP • Delivered over HTTP caching network • HTTP network is more widely deployed than streaming networks • Packet loss is eliminated • Only good for VoD • More overhead than streaming protocols (uses TCP)

45. Live Streaming Over Satellite Network Satellite Uplink Facility Uplink platform Satellite Akamai Servers ISP/Network Datacenter Internet Satellite DVB Receiver Akamai Switch Akamai Streaming Servers IP Encoded Stream x To ISP Subscribers

46. Core Hierarchy Regions XYZ • User requests content and is mapped to optimal edge Akamai server

47. Core Hierarchy Regions XYZ 2. If content is not present in the region, it is requested from most optimal core region

48. Core Hierarchy Regions XYZ 3. Core region makes one request back to origin server

49. Core Hierarchy Regions XYZ 4. Core region can serve many edge regions with one request to origin server

50. Core Hierarch Features Reduces traffic back to origin server • Reduces infrastructure needs of customer • Provides best protection against flash crowds • Especially important for large files (e.g. Operating System updates or video files) Improved end-user response time • Core regions are well connected • Optimized connection speeds object delivery