Content Distribution Internetworking IETF BOF

1. Content DistributionInternetworkingIETF BOF December 12, 2000 Phil Rzewski Gary Tomlinson

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

3. 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

4. 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

5. Content Distribution Internetworking CDN ISP • Interconnect Content Networks • Different administrative domains • Different technologies

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

7. Key Terms&Concepts

8. 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

9. 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

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

11. 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

12. 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

13. Understandingthe StrawmanDrafts

14. 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

15. 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

16. 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

17. 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

18. 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

19. 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

20. 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

21. 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

22. 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

23. 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

24. OrganizationGoing Forward

25. 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