Content Distribution Internetworking IETF BOF December 12, 2000 Phil Rzewski Gary Tomlinson

Content Networking Using IETF “application layer” protocols as transport –e.g. HTTP, RTSP Routing & forwarding of requests & responses instead of packets

Example Content Network: Hierarchical caching ISP client “edge” / “access” caches “parent” cache(s) Typically static forwarding rules –HTTP parenting –ICP Example request forwarding –Single path –Redundant –URL partitioning foo.com bar.com

Example Content Network: Content Distribution Network (CDN)s CDN client “surrogates” “request-routing” system(s) Request routing systems map a client to a surrogate –e.g. DNS Example request forwarding –Ask another surrogate –Seek origin Local DNS

Content Distribution Internetworking CDN ISP Interconnect Content Networks Different administrative domains Different technologies

Content Distribution Internetworking Area of CDI interest lies in communication across these boundaries Details within each Content Network should be irrelevant ???

Key Terms & Concepts

Surrogate “A delivery server, other than the origin. Receives a mapped request and delivers the corresponding content.” client Content Network surrogate origin Delivery “The activity of presenting a publisher’s content for consumption by a client.” delivery

Distribution “The activity of moving a publisher’s content from its origin to one or more surrogates. CN origin CN Injection (aka “origin distribution peering”) “Publishing of content into one-or-more Content Networks by origins.” Content Signal “A message delivered through a distribution system that specifies information about an item of content.” e.g. to indicate the origin has a new version of some piece of content

Request-Routing “The activity of steering or directing a request from a client to a suitable surrogate.” CN client

Accounting “Measurement and recording of distribution and delivery activities, especially when the information recorded is ultimately used as a basis for the subsequent transfer of money, goods, or obligations” CN

Drafting teams Two design teams produced 8 of the 9 drafts The two teams were aligned with Content Bridge & Content Alliance Sharing and cooperation developed late so there is some overlap

Understanding the Strawman Drafts

draft-day-cdnp-model-04.txt Introduction, background, & vocabulary on CDNs –CDN examples provided Introduction & vocabulary on developing CDN interconnection technology –CDN peering examples provided –Content Peering Gateways (CPG) defined Some high-level operational considerations included

draft-day-cdnp-scenarios-02.txt Used to collect the communities of interest requirements Describes representative configurations that can be realized when internetworking CDNs. Framed by the concepts: –CONTENT has value –DISTRIBUTION has value –CLIENTS have value

draft-green-cdnp-gen-arch-02.txt Presents three main architectural elements –Request-Routing Peering System –Distribution Peering System –Accounting Peering System For each architectural element, presents: –Known requirements –Problems that need further investigation Security considerations

draft-green-cdnp-gen-arch-02.txt Conceptual View of Peered CDNs CPG CDN A Request-Routing Distribution Accounting CDN B Request-Routing Distribution Accounting CDN C Request-Routing Distribution Accounting surrogates clients

draft-green-cdnp-gen-arch-02.txt Request-Routing Peering System Architecture Surrogates CDN A client Authoritative Request-Routing System Request-Routing System CDN C Request-Routing CPG Request-Routing System Request-Routing CPG Request-Routing CPG SurrogateSurrogates CDN B Request-Routing CPG Request-Routing System SurrogateSurrogates (1st Level) (2nd Level) Inter-CDN Request-Routing Inter-CDN Recursive Request-Routing draft-cain-cdnp-known-request-routing-00.txt Presents known mechanisms to direct client requests to surrogate servers. –DNS request-routing –Transport-layer request-routing –Application-layer request-routing Discusses measurements, metrics, and feedback draft-deleuze-cdnp-dnsmap-peer-00.txt Proposes a DNS-based Mapping System Focused on determining the next hop toward the appropriate surrogate Describes an approach using CNAME Proposes naming criteria to describe –Delivery service –Delivery Footprint

draft-green-cdnp-gen-arch-02.txt Distribution Peering System Architecture Surrogates CDN A Origin Distribution System CDN C Distribution CPG Distribution System Distribution CPG Distribution CPG SurrogateSurrogates CDN B Distribution CPG Distribution System Surrogates Origin Distribution Peering Inter-CDN Distribution Peering Distribution CPG

draft-green-cdnp-gen-arch-02.txt Accounting Peering System Architecture Surrogates CDN A Origin Accounting System CDN C Accounting CPG Accounting System Accounting CPG Accounting CPG SurrogateSurrogates CDN B Accounting CPG Accounting System Surrogates Origin Accounting Peering Inter-CDN Accounting Peering Accounting CPG Billing Organization Billing Accounting Peering draft-gilletti-cdnp-aaa-reqs-00.txt Requirements for CDN Accounting Peering –Framed against ongoing work of AAA WG Details on CDN Accounting Peering models –Additional terminology –Transaction models –Accounting messaging Lists problems to be solved

draft-rzewski-oacp-00.txt Origin/Access Content Peering for HTTP Specific (“vertical”) implementation proposal of a way to pass control & accounting between origin & access endpoints. –Roles described for specific types of content networks (Hoster/CDN, Operator, Access Provider) Note Request- Routing is a “null case” in the implementation

 New Content Published by Content Provider  Content signals for changed URLs sent to Content Relay at Hoster/CDN  Content signals for changed URLs forwarded to Content Relay at Operator  Content signals for changed URLs forwarded to Content Relay Surrogate at Access Provider  Changed content may be retrieved by Content Relay at Access Provider (HTTP GET)  Content signals for changed URLs forwarded to Access Caches  Access clients request content from Access Caches, if it is not in Access Cache, content is pulled from Content Gateway Surrogate (parent cache) draft-rzewski-oacp-00.txt Access Provider (ISP) Hoster/CDN Content Relay Content Injector Content Relay Surrogate Access Caches Origin Content Relay Operator        www. com Access Clients draft-rzewski-cndistcs-00.txt Proposes specific content signals –HTTP DELETE method for “invalidation” –Also additional “CND: GET” header to kick off pre-load

 Log info is collected and summarized at Access Caches in regular intervals  Access log info is collated at Accounting Relay at Access Provider  Access log information centralized & passed through Operator for settlement and billing  Near real-time summaries are forwarded to Accounting Gateway at Hoster/CDN draft-rzewski-oacp-00.txt ISP 1 Hoster/CDN Accounting Relay Accounting Relay Summary Logging Access Caches Origin     ISP 2 Accounting Relay Summary Logging Access Caches Operator Accounting Relay Settlement & Billing   Access Providers (ISPs) Access Clients draft-rzewski-cnacct-00.txt Proposes SQUID-like summary log format Proposes using HTTP POST to pass log information between networks

Organization Going Forward

Possible Informal Structure Models Scenarios Architecture Framework “umbrella” Accounting Known methods Requirement specifications Proposed protocols Implementation debate Distribution Known methods Requirement specifications Proposed protocols Implementation debate Request-Routing Known methods Requirement specifications Proposed protocols Implementation debate “communities of interest” Other WGs AAAAAA WEBIWEBI DNSextDNSext......