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Internet Content Delivery over Satellite

Internet Content Delivery over Satellite. NANOG October 1999 Evan Baer SkyCache, Inc. SkyCache Overview. History: The Internet is point to point Most data carried on the Internet is broadcast Web Content Usenet News Streaming A/V, FTP data, etc. One to many, not one to one

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Internet Content Delivery over Satellite

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  1. Internet Content Delivery over Satellite NANOG October 1999 Evan Baer SkyCache, Inc. Nanog October/1999

  2. SkyCache Overview • History: The Internet is point to point • Most data carried on the Internet is broadcast • Web Content • Usenet News • Streaming A/V, FTP data, etc. • One to many, not one to one • Satellite technology good fit for broadcast data • Data is transmitted to entire geographic area • Scales to an unlimited number of receivers • SkyCache: Transmit Internet data over satellite, broadcast, to the edge of the network • Work in conjunction with existing Internet infrastructure • Increased efficiency of bandwidth • Move broadcast data to a satellite broadcast overlay network Nanog October/1999

  3. SkyCache Architecture • Distribute Internet data via satellite to the edge of the network • Determine popular web objects by examining cache user requests, transmit popular objects to cache server at the ISP (reactive caching) • Deliver Usenet newsfeed to newsserver at the ISP • Transmit streaming a/v, ftp data, and other future data to servers at the ISP • Internet data collected and transmitted at the Master Control (MC) • MC collects web objects, newsfeed, other data for transmission • Cache miss stream user requests are examined at the MC via a rules system to determine web objects most likely to be cache hits to the SkyCache cache community • Data is aggregated into MC protocol (MCP) and sent to the uplink • Satellite feed received at the SkyCache Adaptor (CA) at the customer site • CA acts as a protocol engine, receiving MCP from the satellite, feeding data via http, nntp, and other protocols to servers at the ISP • Not directly involved in client redirection • SkyCache is a satellite overlay network • Client redirection handled by ISP in current service offerings • Services for content providers will require being involved in end user redirection Nanog October/1999

  4. Full System Architecture Customer Point of Presence (POP) Satellite Receiver SkyCache Adapter SkyCache Uplink GE-3 US GE-1E Europe KU Band 45 Mbs Fast Ethernet 4 Mbs Satellite Dish (on roof) 75-ohm RG6 coaxial cable (approximately. 1Ghz RF signal) Cache Server News Server FTP Server Streaming A/V Future Services Satellite Transmitter Internet L4 Switch Router Master Control Access Server Router Remote Server Dedicated / Dial-Up Customers

  5. Daily Transmit Rates • Transmit rates from September 15-22 • Currently 4MB/s feed • 45 MB/s pipe in testing • Cache turbocharging feed 6-7GB daily • Usenet newsfeed 20-25GB daily Nanog October/1999

  6. Reactive Caching • Internet users typically view the same web content, regardless of location • Mostly true, with some differences for time zone and geographic location • More complex outside of North America (more localized in Europe, for instance) • If the same url is seen from multiple caches, it is probably of interest to the entire community • For any given popular site on the net, someone clicks first • If the url coincidence occurs in a reasonable length of time, minutes or hours, not days • SkyCache rules system detects url coincidences at the MC • Potential win on both ends of web popularity spectrum • Top 10% of sites, which are popular day to day, popular pages from these sites are sent as they expire from the caches and get re-requested • Other 90% of sites, of which different sites may be popular from one day to the next, popular pages from these sites are sent as they are detected as popular • Cacheable content from Yahoo, Wired Magazine, etc. which is sent multiple times per day • Cacheable content from short-term popular sites, such as irs.ustreas.gov during the middle of April Nanog October/1999

  7. Preloading Web Caches • SkyCache CA peers as an ICP sibling with a cache to inject objects and listen to cache miss requests • CA sends the cache an ICP query for a given object • Cache then sends the CA an ICP hit or miss, if it has the object or not • If the CA received an ICP miss, the injection proceeds, and the CA sends the cache an HTTP GET request for the object • The cache then sends an ICP query to the CA for the object • The CA responds with an ICP hit • The cache sends the CA an HTTP GET for the object, and now has the object in cache SkyCache CA Cache ICP_OP_QUERY ICP_OP_MISS or ICP_OP_HIT HTTP GET ICP_OP_QUERY ICP_OP_HIT HTTP GET Nanog October/1999

  8. The Cache Miss Stream • SkyCache CA is queried as an ICP sibling for all cache miss requests • On a cache miss, the cache will send an ICP query to the CA for the requested object • The CA responds with an ICP miss • The cache retrieves the request from the origin server • The CA forwards these url requests to the MC, where they are analyzed • On a cache hit, the request is served from the cache, and the CA is never queried Origin Web Server HTTP GET Cache User Cache SkyCache CA HTTP GET ICP_OP_QUERY ICP_OP_MISS Nanog October/1999

  9. Finding popular web objects • US miss stream from September 15-22 • ~15 million urls daily, from ~75 unique US cache locations • Cache miss stream is comprised of all cache miss requests from all active SkyCache enabled caches • Popular objects defined as an object which has been seen multiple times from multiple caches • 10-15% of all urls in the miss stream are found to be popular • Nearly equal number of cacheable and noncacheable objects Nanog October/1999

  10. Cache Performance Increase • SkyCache injected objects only make an impact on the first hit • Example: 1 cache miss and 10 cache hits on www.foo.com, can only convert the first miss to a hit • Unique hits are tallied to determine the most benefit which could be made to a cache’s hit rates • Best suited to small and medium caches • Cache object hit rate can get to %50-55 with SkyCache, past that is more a function of user base • 10,000 users request 25,000 different urls • 100,000 users request 35,000 different urls, more hits on the same objects • Regional caches, servicing > 3M cache requests per day, have a cache community to large to make use of SkyCache’s virtual cache community Nanog October/1999

  11. Examining Unique Hits • Unique hits for 3 SkyCache enabled caches from September 15-22 • 40-50% of unique hits are on SkyCache injected objects Nanog October/1999

  12. Increased Cache Object Hit Rates • Increase in object hit rates on SkyCache enabled caches from September 15-22 • 15-20% increase of object hit rate due to hits on SkyCache objects • 8-12% points on top of standard cache hit rate Nanog October/1999

  13. Increased Cache Byte Hit Rates • Increase in byte hit rate on SkyCache enabled caches from September 15-22 • 25-30% increase of byte hit rate due to hits on SkyCache objects • 8-10% points on top of standard cache byte hit rate Nanog October/1999

  14. Usenet Newsfeed delivered over satellite, sustained 2.5-3MB/s SkyCache CA appears as a NNTP feeder Snapshot of 3 customers on September 24th, 1999 5 minute throughput rates in megabytes Feed rates depend upon other customer news peers, many other factors Fairly obvious when expirations / other server maintenance occurs Usenet News Nanog October/1999

  15. Issues in satellite delivery to edge servers • Determing effectiveness of delivered data no simple task • Currently requires post analysis of cache access logs • Cache misses are seen in the current ICP cache peering mechanism, not hits • Newsfeed impact is more straightforward, as news was built for feeds • Pushing protocols to do things they weren’t really intended to do • NNTP fairly simple, protocol meant to feed objects • Slight abuse of ICP and HTTP to inject objects into caches, currently no other standard protocols • Streaming A/V protocols also a bit tricky to deliver in broadcast fashion • For current ISP targeted services, client redirection handled by ISP • Future content provider driven services require managing client redirection Nanog October/1999

  16. Future • Broadcast data not on the Internet as we know it • Overlay networks to distribute content aimed at the masses • Alternative content delivery becomes more interesting and accepted as end users get high speed connectivity and become less tolerant of high latency • Content providers will be pushed to distribute content by the end user • Overlay networks, server distribution, and caching will all play a role • Growth of caching as accepted practice, more functionality • Better and more widely supported cache protocols • Passing of cache usage information to peers and content providers • More information about cacheable sites, cache breaking sites on the Net • Cacheable / Uncacheable web sites continue to be balanced • Some sites will continue to have uncacheable pages, some will make their pages cache friendly. Not all sites will become dynamic or uncacheable, nor will all sites become cacheable. Nanog October/1999

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