#CLUS Content Delivery Networks (CDN) Caching Principles, Architecture, and Resource Optimization Scott Wainner, Distinguished SE BRKSPV-2160 #CLUS Cisco Webex Teams Questions? Use Cisco Webex Teams (formerly Cisco Spark) to chat with the speaker after the session How 1 Find this session in the Cisco Events App 2 Click “Join the Discussion” 3 Install Webex Teams or go directly to the team space 4 Enter messages/questions in the team space Webex Teams will be moderated cs.co/ciscolivebot# BRKSPV-2160 by the speaker until June 18, 2018. #CLUS BRKSPV-2160 © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public 3 Agenda • Caching Principles • Caching Value Proposition Models • Content Delivery Functions • Content Delivery of Media Services • Platform Optimization and Management • Enabling Cloud Content Delivery #CLUS BRKSPV-2160 © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public 4 Objectives • Understand Principles of Caching • Understand System Architecture and Role of CDN • Distinguish Impact of Service Delivery Models • Assess Characteristics of Resource Optimization Content Caching Principles Relevance Many Media Types and Purposes • Commercial Video • Imagery • Production Training / Education Systems • Marketing / Mass Communication Systems • Notification Information Distribution • Telemetry Distribution to Subscribers • Software Distribution #CLUS BRKSPV-2160 © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public 7 Content Distribution Principles Efficiency Performance Resiliency #CLUS BRKSPV-2160 © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public 8 Content Distribution Architectural Models • Hierarchical • Distribution Tree from Origin C C • Often associated with an Authoritative Source • Tightly controlled distribution policies C • Peer to peer • Distributed Hash Table model C C C • Content can be cached anywhere • Appropriate in fully meshed topologies • Multiple sources C C C #CLUS BRKSPV-2160 © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public 9 Metadata Live Media Live ABR traffic System Architecture Video Control VOD Media VOD ABR traffic Content Management Offer Management Authentication Product Bundles Entitlement Catalog Personalization Live EPG And Navigation Workflows Policy Billing VoD IMDb Catalog Creation Digital Rights Offers Subscriptions Entitlement & Image Tags Asset Management Policy Session Management Session Control Policy Management Video Control Plane Clients Data Plane Credentials Transcoding Origin Servers Content Delivery Content Distribution Streams Live Live Origin Servers Mid-Tier Edge On Cache Cache VOD Origin Servers Images Demand Software Authorization Video Storage Cache Cache & Assignment Content Acquisition Our Focus Today #CLUS BRKSPV-2160 © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public 10 CDN Systems Architecture Published Internet Content Content Programming Centralized Content, Command and Control, Traffic Traffic Ingest, Routing Ops Content Library and Analytics (Origin) Routing, & Management Hierarchy of Origination, Mid-Tier and Edge Caching Traffic (Optional) Servers Management Plane, Caching Layer Content Routing Plane, Content Delivery Plane Traffic Optimized Resiliency Defined Servers Edge Cache at each Tier Cost Optimized Platform Selection Entertainment Services Entertainment Services Off-Net On-Net #CLUS BRKSPV-2160 © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public 11 Content Caching Techniques CDN - Introduction to Dynamic Caching • Concepts • CDN is a “Proxy” for Origin Content Delivery Network Servers • Redirecting clients to CDN Location Requests Traffic Routing Location Redirects • CDN Functional Cache Mid-Tier Edge Origin Content Content Elements Servers Cache Content Cache Requests Requests Requests Ingest • “Traffic Routing” Redirection Cache-Fill • “Origin Server” Library Cache Cache Streams • “Traffic Server” Caching Content Storage Storage • “Traffic Server” Edge Cache Library #CLUS BRKSPV-2160 © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public 13 CDN – Implementation Considerations • Storage Considerations Caching Characterization • Live Media (Finite Window) • VoD Media (Natural Expiration) • Cloud DVR (No Caching) Input Output • Content Affinity Cache-Fill or Ingest • Localization Cache-Fill • Mobile Main memory or Edge Cache • Pre-positioned Solid state disk • Mapping Methodology • File Handle in URL Spinning disk • Byte Offset in URL • Retention / Eviction Algorithms • Least Recently Used • First In / First Out • Metadata (Algorithmic Expiration) #CLUS BRKSPV-2160 © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public 14 HTTP Caching Transparent Caching • RFC2616 HTTP/1.1 Origin • RFC 6585 Status Codes Server • RFC 2817 TLS • RFC 5785 Well-Known URI Internet get ([email protected]) • RFC 6266 Content-Disposition • Cache Types Intercept Transparent x x • Transparent Caches Cache • Proxy Caches get ([email protected]) #CLUS BRKSPV-2160 © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public 15 Transparent Caching • Unauthorized Intercept Catalog Origin Server 1 • Non Monetized • Dynamic Interpretation of Request Item: x GET Location (fqdn-y) • HTTP GET Analysis Internet ([email protected]) 2 • Authentication or Encryption Interference Item (x, Location (fqdn-y)) 6 STOP7 • Authentication • Token or HASH Validation Corrupted 5 Intercept • Payload Encryption Transparent x x Cache • (e.g. Media Headers, Opaque Objects) • Transport Encryption STOP8 4 9 • (e.g. TLS, SPDR) get ([email protected]) 3 DNS Location (fqdn-y.com) #CLUS BRKSPV-2160 © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public 16 HTTP Caching • RFC2616 HTTP/1.1 Proxy Caching • Origin RFC 6585 Status Codes Server • RFC 2817 TLS get ([email protected]) • RFC 5785 Well-Known URI • RFC 6266 Content-Disposition • Cache Types Rewrite • Transparent Caches Proxy z y Cache • Proxy Caches get ([email protected]) #CLUS BRKSPV-2160 © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public 17 Proxy Caching Origin Server Catalog • Authorized Delegation 1 • Explicit Interpretation Provided to Cache Item ([email protected]) 6 Item ([email protected]) • Optimized Payload is Known a priori get ([email protected]) 3 • Authentication or Encryption Viable 2 Location: • Authenticators Validated and (fqdn-a.com fqdn-b.com) Recalculated Proxy Cache • Tokens, HASH fqdn-a fqdn-b • Private Keys Shared • Payload Remains Encrypted • Substitution of Opaque Payload get ([email protected]) • Transport Encryption 5 • Public Certificates Exchanged DNS 4 FQDN (fqdn-a) #CLUS BRKSPV-2160 © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public 18 CDN Caching Basics Origin Server Catalog • Authorized Delegation 1 • Explicit Interpretation Provided to Item ([email protected]) Cache get ([email protected]) Item ([email protected]) 9 3 • Authentication or Encryption Viable CDN Traffic 2 • Redirection to Optimal Location Server Asset Mapping (Cache) ( [email protected] [email protected]) • Cache Hit Ratio Traffic 8 Router get ([email protected]) • Distributed Edge Traffic Server • Edge Cache (Caching) • Intermediate Layer 7 • Reverse Proxy Cache get ([email protected]) GET ([email protected]) 5 Redirect ([email protected]) 6 cdn.com DNS 4 #CLUS BRKSPV-2160 © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public 19 CDN Value Proposition Content Caching Principles Cost Optimized Costs Cache Costs Bandwidth Costs Cache Hit Rates Caching Sites Cost Inflection Point Content Popularity #CLUS BRKSPV-2160 © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public 21 Content Popularity Content Popularity Often Characterized by Zipf’s Law Library Described by Alpha (α) Each Library is Unique • Old Movies • Current Hits Views • Music Videos • Sports Highlights • TV Series Top 100 Bottom 100 Titles ranked by Demand Cache #CLUS BRKSPV-2160 © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public 22 Contributing Factors • CHR of Content Types • ABR more difficult to predict than for PDL • Cache Fill Traffic • Temporary content renewal Different Nodal • Triggered by revalidation • First Fill Request Cache Hit Rates !!! • Eviction • Popularity Profile • Least Recently Used • Topology Considerations • Hierarchical Caching gains • Geographical Content Affinity #CLUS BRKSPV-2160 © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public 23 Nodal Cache Hit Rates Content Requests • Probability of a Cache Hit 2 5 13 2/2 = PCHR 100% • Probability of a Nodal Cache Miss PCM = 1- PCHR • Node A Cache Miss Origin 3/5 = PCHRa = 3/5 = 0.60 or 60% 60% PCMa = 1 – 0.60 = 0. 4 New Content / Cache • Node B Cache Miss Unpopular Content (a) 8/13 = 61.6% PCHRb = 8/13 = 0.616 or 61.6% Some Popular Content Cache PCMb= 1 – 0.616 = 0.384 Very Popular Content (b) #CLUS BRKSPV-2160 © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public 24 System Cache Hit Rates Content Requests 2 5 13 • Probability of System Cache Miss 2/2 P = P * P SCM CMa CMb = • System Cache Miss Example 100% PCHRa = 3/5 = 0.60 or 60% P = 1 – 0.60 = 0. 4 CMa Origin 3/5 PCHRb = 8/13 = 0.616 or 61.6% = 60% PCMb= 1 – 0.616 = 0.384 Cache (a) 8/13 PSCM = 0.4 * 0.384 = 0.154 = 15.4% = • System Cache Hit Rate = 1- 15.4% = 84.6% 62% Cache (b) #CLUS BRKSPV-2160 © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public 25 Caching Cost : Bandwidth Cost Demand Contributions / Cache-fill Bandwidth Costs Source Data Network Network Access Home Center Core Edge Network Network #CLUS BRKSPV-2160 © 2018