Cachet Technologies 1998 Cachet Technologies Technology Overview February 1998

Cachet Technologies 1998

Cachet TechnologiesCachet Technologies

Technology OverviewTechnology Overview

February 1998February 1998


OutlineOutline

Our Technology FocusOur Technology Focus First Application: Caching at the Edge of the First Application: Caching at the Edge of the

InternetInternet Comparison with Competing ProductsComparison with Competing Products Some Details of the TechnologySome Details of the Technology

– A new hashing protocolA new hashing protocol Other Potential ApplicationsOther Potential Applications Current PlansCurrent Plans


Technology FocusTechnology Focus

General:General:– Development of applications and infrastructure Development of applications and infrastructure

for distributed networks such as the Internet.for distributed networks such as the Internet. Current Emphasis:Current Emphasis:

– A solution to the A solution to the Resource Location ProblemResource Location Problem in in distributed networks.distributed networks.


Resource Location ProblemResource Location Problem

Where to put “it”Where to put “it” and and how to find “it”how to find “it” in a in a rapidly changing environment where there rapidly changing environment where there is no centralized control and information is is no centralized control and information is imperfect.imperfect.


First ApplicationFirst Application

Construction of large distributed caches at Construction of large distributed caches at the edges of the Internetthe edges of the Internet– Keeps commonly accessed items close to usersKeeps commonly accessed items close to users– Results in improved performance (e.g. latency) Results in improved performance (e.g. latency)

for users and decreased cost (e.g. bandwidth for users and decreased cost (e.g. bandwidth utilization) for service providersutilization) for service providers

– Can be sold to service providers and/or user Can be sold to service providers and/or user groups (e.g. companies) with 10-10M membersgroups (e.g. companies) with 10-10M members


ExampleExample

ISP

Internet

CNN

MIT

IBM

Users


ExampleExample

ISP

Internet

CNN

MIT

IBM

Cache

Users


Different ApproachesDifferent Approaches

Proxy Caches Proxy Caches (Microsoft, Cacheflow)(Microsoft, Cacheflow)

Monolithic Caches Monolithic Caches (Cisco, Inktomi)(Cisco, Inktomi)

– Large caches made up of clusters of machines Large caches made up of clusters of machines under under centralized controlcentralized control and placed at a and placed at a specific specific pointpoint in the network in the network

Distributed Caches Distributed Caches (NetCache)(NetCache)

– Large cache made up of Large cache made up of loosely coupledloosely coupled machines that are machines that are spread throughout the networkspread throughout the network


Monolithic vs. DistributedMonolithic vs. Distributed

Need faster response time for usersNeed faster response time for users– Caches should be close to the users at the edges Caches should be close to the users at the edges

of the network (Distributed)of the network (Distributed) Need reduced traffic out of networkNeed reduced traffic out of network

– Cache should have large capacity (Monolithic?)Cache should have large capacity (Monolithic?) Cachet’s Vision: Cachet’s Vision: DistributedDistributed caches that caches that

cooperatecooperate to form a cache with to form a cache with large large aggregate capacityaggregate capacity..


Necessary ComponentsNecessary Components

Resource LocationResource Location– Where do I put it and how do I find it?Where do I put it and how do I find it?

Resource DiscoveryResource Discovery– Who else is out there that will cooperate with Who else is out there that will cooperate with

me?me? Preventing Hot SpotsPreventing Hot Spots

– How do I cooperate without being overloaded How do I cooperate without being overloaded by requests?by requests?


Our Key TechnologiesOur Key Technologies

Invention of Invention of Consistent HashingConsistent Hashing to solve to solve resource location problemresource location problem

Discovery of protocols that enable caches to Discovery of protocols that enable caches to learn about the networklearn about the network

Development of a novel replication strategy Development of a novel replication strategy to prevent hot spotsto prevent hot spots– i.e. when to make more copies?i.e. when to make more copies?


Our AdvantagesOur Advantages

No special purpose hardwareNo special purpose hardware No centralized controlNo centralized control

– Very loosely coupled network of cachesVery loosely coupled network of caches Perfect information on status of caches is Perfect information on status of caches is

not needednot needed Fully scaleable and fault tolerantFully scaleable and fault tolerant Automatic load balancing Automatic load balancing Prevents swamping and hot spotsPrevents swamping and hot spots


Some of the DifficultiesSome of the Difficulties

Standard Way: Hashing h(x) = ax+b mod nStandard Way: Hashing h(x) = ax+b mod n

X

Where do I put file X?Where do I put file X? 1

2

3 4

5


Standard Hashing: The GoodStandard Hashing: The Good

Balanced loadBalanced load

Fast to compute Fast to compute

Local controlLocal control


Standard Hashing: The BadStandard Hashing: The Bad

Perfect information is neededPerfect information is needed

ax+b mod 4 = 2




ax+b mod 4 = 2




ax+b mod 4 = 2





Standard Hashing: The UglyStandard Hashing: The Ugly

Small changes in the system cause drastic Small changes in the system cause drastic changes in the cachechanges in the cache

1 2 3 4 5 6 7 8 9 10 11

A

B

C

Caches

Pages


Standard Hashing: The UglyStandard Hashing: The Ugly

Small changes in the system cause drastic Small changes in the system cause drastic changes in the cachechanges in the cache

1 2 3 4 5 6 7 8 9 10 11

A

B

C

Caches

Pages

D


Standard Hashing: SummaryStandard Hashing: Summary

Useless for large and/or evolving distributed Useless for large and/or evolving distributed networksnetworks


Consistent HashingConsistent Hashing

Consistency under changing rangesConsistency under changing ranges

1 2 3 4 5 6 7 8 9 10 11

A

B

C

Caches

Pages


Consistent HashingConsistent Hashing

Consistency under changing rangesConsistency under changing ranges

1 2 3 4 5 6 7 8 9 10 11

A

B

C

Caches

Pages

D


Consistent Hashing: FeaturesConsistent Hashing: Features

Continuous balanced loadContinuous balanced load Fast to computeFast to compute Local controlLocal control Scales without any catastrophic updatingScales without any catastrophic updating Users need only partially correct view of the Users need only partially correct view of the

network. Enables network. Enables “lazy” resource discovery“lazy” resource discovery.. Enables resource location to take into account Enables resource location to take into account

load balancingload balancing and and geographic information.geographic information.


Related ApplicationsRelated Applications

Eliminating hot spots on the web (same Eliminating hot spots on the web (same technology on larger scale)technology on larger scale)

Distributed file serversDistributed file servers Swamping protection as a serviceSwamping protection as a service Distributed e-mail serversDistributed e-mail servers On-line moviesOn-line movies


Current PlansCurrent Plans

Implement Demo 1.0 at LCSImplement Demo 1.0 at LCS– Software package installed by user Software package installed by user – Program integrates automatically into loosly-coupled Program integrates automatically into loosly-coupled

distributed cachedistributed cache– Distributed cache performs as if a large virtual cache Distributed cache performs as if a large virtual cache

existed between LCS and the Internetexisted between LCS and the Internet

Development of market strategy and business Development of market strategy and business planplan

Secure VC funding and identify CEO for Secure VC funding and identify CEO for companycompany

Documents

Cachet Technologies 1998 Cachet Technologies Technology Overview February 1998