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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.
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Content DistributionInternetworkingIETF 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 “parent” cache(s) ISP foo.com bar.com “edge” / “access” caches • Typically static forwarding rules • HTTP parenting • ICP client • Example request forwarding • Single path • Redundant • URL partitioning
Example Content Network:Content Distribution Network (CDN)s “request-routing” system(s) CDN “surrogates” • Request routing systems map a client to a surrogate • e.g. DNS Local DNS • Example request forwarding • Ask another surrogate • Seek origin client
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
Surrogate “A delivery server, other than the origin. Receives a mapped request and delivers the corresponding content.” Delivery “The activity of presenting a publisher’s content for consumption by a client.” origin Content Network surrogate delivery client
Distribution “The activity of moving a publisher’s content from its origin to one or more surrogates. Injection (aka “origin distribution peering”) “Publishing of content into one-or-more Content Networks by origins.” CN origin CN CN 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 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 CN 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
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.txtConceptual View of Peered CDNs CDN A CDN B Request-Routing Request-Routing CPG CPG Distribution Distribution Accounting Accounting CPG surrogates surrogates CDN C Request-Routing Distribution Accounting surrogates clients
draft-green-cdnp-gen-arch-02.txtRequest-Routing Peering System Architecture client Authoritative Request-Routing System Inter-CDN 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 (1st Level) Request-Routing CPG Request-Routing CPG 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 CDN A Request-Routing System CDN B Request-Routing System Request-Routing CPG Surrogates Surrogate Surrogates Inter-CDN Recursive Request-Routing Request-Routing CPG (2nd Level) CDN C Request-Routing System Surrogate Surrogates
draft-green-cdnp-gen-arch-02.txtDistribution Peering System Architecture Origin Origin Distribution Peering Distribution CPG Distribution CPG CDN A Distribution System CDN B Distribution System Surrogates Distribution CPG Distribution CPG Surrogates Inter-CDN Distribution Peering Distribution CPG CDN C Distribution System Surrogate Surrogates
draft-green-cdnp-gen-arch-02.txtAccounting Peering System Architecture Billing Organization Origin Billing Accounting Peering Origin Accounting Peering Accounting CPG Accounting CPG CDN A Accounting System CDN B Accounting System 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 Surrogates Accounting CPG Accounting CPG Surrogates Inter-CDN Accounting Peering Accounting CPG CDN C Accounting System Surrogate Surrogates
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
Operator draft-rzewski-oacp-00.txt Hoster/CDN Access Provider (ISP) Access Caches Origin www.com Access Clients Content Relay Surrogate Content Relay Content Injector Content Relay 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-cndistcs-00.txt • Proposes specific content signals • HTTP DELETE method for “invalidation” • Also additional “CND: GET” header to kick off pre-load
draft-rzewski-oacp-00.txt Hoster/CDN Access Providers (ISPs) Access Caches Operator Accounting Relay ISP 1 Origin Summary Logging Access Clients Accounting Relay Accounting Relay Access Caches ISP 2 Settlement & Billing draft-rzewski-cnacct-00.txt • Proposes SQUID-like summary log format • Proposes using HTTP POST to pass log information between networks 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 Accounting Relay Summary Logging
Possible Informal Structure Models Scenarios Architecture Framework “umbrella” Other WGs A A A W E B I D NS e x t . . . “communities of interest” 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