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This paper by Micah Beck discusses the fundamental principles guiding the design of scalable Internet services. Emphasizing end-to-end arguments, it highlights key maxims, such as avoiding complexity at intermediate nodes and advocating for resource use only when necessary. The concept of deployment scalability—the ability to scale freely across boundaries—is explained, along with real-world applications like the Internet Backplane Protocol (IBP). The paper examines the balance between resource sharing, simplicity, and service specialization, aiming for robust network performance.
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Achieving Deployment Scalability Micah Beck Director & Associate Professor Logistical Computing and Internetworking Lab Computer Science Department University of Tennessee Cambridge University 9/27/2004
End-to-End Arguments • Principles that guided the design of the Internet • It took the form of a number of maxims, rules of thumb and “end-to-end arguments” • “Never implement a complex service at an intermediate node if the complexity can be moved to the endpoint” • “Never use the resources of intermediate nodes to implement services that are not ubiquitously required by applications” • The penalty for Violating End-to-End: “It won’t scale!”
Deployment Scalability • Scalability has many dimensions • number of users • attached devices • traffic volume • networks & admin domains subsumed • economic rationality • Correct operation & acceptable performance • We use the term deployment scalability to mean the ability to scale freely across boundaries • primary example: the Internet
A Scalability Principle • When designing a service that is implemented using a shared infrastructure, there is an inherent tradeoff between • the service’s scalability on that infrastructure, • and both • its specialization to a particular class of applications, and • the value or scarcity of the resource consumed to provide atomic services.
Applying the Scalability Principle to Server Resources • Consider intermediate nodes with server resources • Moore’s law makes server resources cheap • Sharing server resources may be a necessary cost of scalability • Networks share massive bandwidth resources • Scalability requirements, according to our scalability principle • Services must be simple, generic, unreliable • Any single service request must not give away resources that are too scarce or too valuable. • Can we fashion services that will scale?
Internet Backplane Protocol (IBP): Scalable Storage and Computation • Storage and processing implemented at IBP intermediate nodes called “depots” • IP limits the maximum size & time-to-live (in hops) of a datagram • IBP limits the maximum size and duration (in secs) of a storage allocation • IBP limits the maximum size and processing time (in CPU secs) of an operation parameter • IP datagram delivery is best-effort • IBP storage and computation are best-effort • IP routers are untrusted • IBP depots are untrusted
The Transnet: A Unified View of Data Transfer, Storage and Processing “… memory locations … are just wires turned sideways in time” Dan Hillis, 1982,Why Computer Science is No Good
Storage as “Movement” Through Time A A A M M M
Message as “Process” C B A M’’ M M’
Processing as “Movement” Through Space of Values A A A M3 M1 M2
Compute Nodes as Intermediate Nodes • Minimize state and trust • Distinguish hard and soft state clearly and manage the latter aggressively for resource sharing • Define primitive common interfaces at a low level in order to enable heterogeneity in OS services • Expose state of long-running “processes” to manipulation by “endpoints”
