Renovating the Internet
SkyCache[TM] White Paper
February 5, 1998

Introduction

   The Internet is fundamentally unbalanced.

   The click of a mouse button on a web page sends a 30 to 50 character URL - a web address, down an Internet connection. The response from the destination web server can be anywhere from 25 to 700K of web page information, between text, hypertext, and pictures, with audio and video thrown in for good measure.

   Multiply the one web click by a hundred, a thousand, ten thousand web surfers and one begins to see why Internet Service Providers are running multiple leased lines at white-hot capacity. One also begins to understand why the World Wide Web has earned the nickname "World Wide Wait," between overloaded communications links, congestion at National Access Points (NAPs), and overburdened popular web servers, such as the Mars Pathfinder Mission. Buying larger leased line "pipes" may provide short-term relief but not a long-term solution. Greater deployment of ISDN, cable modems, and xDSL services that increase bandwidth into the home will place expanding strains on ISPs, furthering the need for higher capacity.

Caching - A first step

   Caching - storing frequently accessed information on a local server - can help to ease the burden on overloaded leased lines. Popular web pages and other information are stored once on an ISP's local cache box, rather than the same copy of information requested and sent back down to the Internet Service Provider time after time. Since one copy of the most popular information is stored locally, web surfers experience faster response time because they access the copy across the ISP's local area network, rather than jumping through multiple hops across a NAP to a heavily loaded web server. The ISP wins because their connections to the Net are not burdened with the same information flogged down their lines hundreds and thousands of times per hour.

   However, a cache still needs to acquire the first copy through the leased line. Further, a local cache's hit rate will be dictated by the size of the number of users it has, or its "community." Assuming the same amount of disk, a few hundred people to a thousand people accessing a cache will typically have widely differing interests resulting in lower hit rates, but hundreds of thousands of people will develop patterns that translate into higher cache hit rates. For example, if we were going to statistically sample an office building of a thousand people, the results we would get would not be as revealing as statistically sampling a city of one hundred thousand people. The larger community size would produce better quality statistics. In a cache, better quality statistics - the most popular items accessed on a cache - translate to higher cache hit rates.

Terabyte Community Cache - Better

   Several companies are building large terabyte-sized "community" caches positioned at the NAPs that serve as hierarchical update caches. In theory, the community cache provides a localized means for an ISP cache to be updated in a small number of hops, cutting down the time the first copy of a web page arrives at the local cache. Local caches pull down updates through a traditional leased-line connection.

   However, the community cache itself becomes a bottleneck for local cache updating, since local caches must communicate with it at a NAP. Further, the community cache ends up generating a large amount of traffic ensuring that its copies of information are the most up to date. It remains unclear if the performance savings from using a hierarchical cache significantly outweigh the penalty imposed by having to traverse the NAP for updates.

SkyCache[TM] - Best

   SkyCache[TM] uses off-the-shelf satellite data broadcast and caching technologies to bypass bottlenecks imposed by the existing Internet infrastructure. A local cache at the ISP level constantly receives updates of the most popular web sites through a high-speed satellite link, avoiding leased line congestion and NAP bottlenecks. Since the information is broadcast directly through the satellite to all local caches in parallel, every ISP's cache is updated at the same time without delay. This scheme frees up bandwidth across the network.

   Each local ISP cache reports back hit/miss statistics to a "master cache" that aggregates the information into a large "virtual cache community." This virtual cache community provides a rich statistical win for all local ISP caches, whether or not the local ISP has a thousand or one hundred thousand customers using their cache.

   Existing Internet leased line performance is significantly improved for the ISP. The master cache has a large community that produces good data in order to optimize caching. Caching keeps frequently accessed information locally at the ISP level so customers benefit from faster performance. Bandwidth is freed up by both caching and by updating the cache's contents through the satellite broadcast link. Anywhere from 30-60% of bandwidth may be freed up by the use of SkyCache services, forestalling the need to purchase more leased lines.

   SkyCache operates as a service. The low monthly fee covers the cost of equipment, software, and maintenance as well as the satellite-based updating from the master cache. Bandwidth is freed, effectively adding capacity for the ISP while greatly reducing the ISP's bottom line when compared to the cost of additional leased lines. Because SkyCache is a service, no capital expenses are incurred by the ISP for hardware, software, service, or support. A service/leasing model allows ISPs to better manage cash flow.

Infrastructure for the future

   SkyCache is a satellite data delivery company whose first product has a cache at the end of the dish. Future products will have the capability to deliver databases, large software distributions, streaming audio and video, and push content. While IP multicast is being pitched as a "one size fits all" solution to Internet broadcast, many ISPs are looking for alternatives to deliver bandwidth-heavy applications without burdening expensive national leased line networks.

"SkyCache" and its logo are trademarked throughout the world; worldwide patents pending on certain technologies used by SkyCache, Inc., 312 Laurel Avenue, Laurel, Maryland 20707, USA.

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Questions and comments should be directed to:

Doug Mohney Director of Marketing e-mail moo@skycache.com (v) 301-598-0500