Re: [CDNi] CDNI FCI meeting at IETF-89

[Jan Seedorf <[e-mail]>]

Thanks to all who filled in the doodle so far, it seems that TUE 13:00-15:00 is the best slot; however, Daryl cannot make that one. Any chance you can make a slot before WED afternoon, Daryl?

The 2nd best slot is WED 15:30-17:30, but Kevin cannot make that one. Kevin?

Darly, Kevin, any chance that you guys can in fact make the respective slot above?

 - Jan

> -----Original Message-----
> From: CDNi [mailto:[e-mail]] On Behalf Of Jan Seedorf
> Sent: Thursday, February 27, 2014 3:30 PM
> To: [e-mail]
> Subject: [CDNi] CDNI FCI meeting at IETF-89
> 
> Dear all,
> 
> I took the liberty of setting up a doodle to have some discussions on how to
> continue with the two current FCI proposals during the IETF-89 week (the
> chairs allocated some time in the official CDNI slot on THU, but I am afraid it
> will not be enough if we want to make some progress):
> 
> http://www.doodle.com/xfn59dgm5nit9v4a#table
> 
> I also took the liberty of inviting the ALTO chairs (in cc), as they can hopefully
> enlighten us on the ALTO WG timeframe and re-chartering, as dependency
> on the progress of the ALTO WG has repeatedly been mentioned as being a
> drawback of an ALTO-based approach.
> 
> Please all fill in the doodle if you would like to participate in this meeting at
> IETF-89.
> 
>  - Jan
> 
> > -----Original Message-----
> > From: CDNi [mailto:[e-mail]] On Behalf Of Matt Caulfield
> > (mcaulfie)
> > Sent: Saturday, February 22, 2014 9:51 AM
> > To: [e-mail]
> > Subject: [CDNi] FCI Analysis
> >
> > As promised in Vancouver, I have read through the two current FCI
> proposals
> > (along with some of their normative references) and I have put together
> the
> > following analysis.
> >
> > The text below first reviews the CDNI Requirements for FCI as well as some
> > of the highlights from the FCI Semantics. Next, a short list of (what I feel
> are)
> > the key points from each draft. Finally, my analysis comparing the drafts
> > based on their approach to FCI (and not the quality or the level of detail in
> > the documents).
> >
> > If you have not done so already, then I would also  recommend reading Jon
> > Peterson's email from February 6 ("footprint and capabilities
> mechanisms").
> >
> > =======================================
> > FCI Requirements (draft-ietf-cdni-requirements)
> > -------------------------------------------------------------
> > The CDNI FCI must allow a dCDN to communicate the following to a uCDN:
> > 1) Ability/willingness of dCDN to handle requests from uCDN
> > 2) Information to facilitate selection of a dCDN by uCDN (e.g. capabilities,
> > resources, affinities)
> > 3) Aggregated versions of #1 and #2 in the cascaded CDN case
> > 4) Administrative limits and policies (e.g. max number of requests)
> > 5) Specific capabilities including:
> > 	a) delivery protocol
> > 	b) acquisition protocol
> > 	c) redirection mode (DNS vs HTTP)
> > 	d) logging options
> > 	e) metadata options
> > 6) Delivery authorization mechanisms (e.g. uri signing)
> >
> > The FCI must also support extensibility and versioning for new capabilities
> > and footprints.
> >
> > =======================================
> > FCI Semantics (draft-ietf-cdni-footprint-capabilities-semantics)
> > -------------------------------------------------------------
> > Design Decisions
> > 1) Advertising Limited Coverage - should footprints be binary or rated via
> > qualitative score?
> > 2) Capabilities and Dynamic Data - what capabilities are static vs dynamic? If
> > dynamic, how dynamic?
> > 3) Advertisement vs Queries - synchronous query response model (per
> end
> > client request) or state replication?
> > 4) Avoiding / Handling Cheating dCDNs - capabilities should be eventually
> > verifiable by the uCDN
> >
> > Mandatory footprint types:
> > 1) List of ISO Country Codes
> > 2) List of AS numbers
> > 3) Set of IP-prefixes
> >
> > FCI must be able to convey the entire footprint/capabilities and optionally
> > dynamic updates.
> >
> > Footprints and Capabilities are dependent and tied together. Certain
> > capabilities are only available for specific footprints.
> >
> > Important to note that most footprint information will be agreed upon out
> of
> > band (e.g. via contracts). FCI can be considered a means for providing
> > changes or updates to that previously agreed upon set of footprints and
> > capabilities.
> >
> > =======================================
> >  FCI using ALTO (draft-seedorf-cdni-request-routing-alto-06)
> > -------------------------------------------------------------
> > This proposal is based on the ALTO (Application Layer Traffic Optimization)
> > protocol (draft-ietf-alto-protocol), currently under development by the
> ALTO
> > working group. ALTO protocol specification is currently an Active Internet-
> > Draft in the "Submitted to IESG for Publication" state.
> >
> > Each dCDN hosts an ALTO server. The uCDN uses an ALTO client to
> determine
> > footprint and capabilities of dCDN.
> >
> > An ALTO Network Map indicates coverage/reachability to groups of
> > endpoints. Endpoints are grouped into PIDs. All endpoints within a single
> PID
> > share the same capabilities.
> >
> > Each PID is associated with a set of properties. Each property corresponds
> to
> > a capability. The concept of a PID Property Map is defined by draft-roome-
> > alto-pid-properties (an active Internet-Draft). The same draft defines rules
> > for implicit inheritance of properties for overlapping PIDs (e.g. one PID may
> > correspond to a set of IP prefixes which is a subset of another PID; in this
> > case, properties in the PID Property Map for the bigger set (i.e. shorter IP
> > prefix) also apply to the smaller set (i.e. longer IP prefix)).
> >
> > Presumably the uCDN is configured with the URI for an ALTO IRD
> > (Information Resource Directory) per dCDN. The IRD in turn provides two
> > URIs. One for accessing the dCDN's Network Map and another for the
> > dCDN's PID Property Map. However, this is not described explicitly.
> >
> > The draft defines the same basic set of capabilities as defined in the
> > requirements but does not describe their encoding in depth.
> >
> > The ALTO protocol only registers IPv4 and IPv6 endpoint types. Assuming
> > that this draft would register ISO Country Codes and AS numbers as new
> > endpoint types, but not clear from the text.
> >
> > ALTO Cost Map could be used to determine the cost of the dCDN delivering
> > to each group of endpoints (PID).
> >
> > The PID concept offers a level of indirection between footprints and
> > capabilities allowing them to vary independently.
> >
> > ALTO also offers filtered querying in order to avoid fetching an entire
> > network map or pid property map.
> >
> > Future extensions to ALTO will include asynchronous notifications and
> > incremental updates as described by draft-schwan-alto-incr-updates
> > (currently an Expired Internet-Draft). Expecting progress soon in this area
> > from the ALTO WG.
> >
> > =======================================
> > FCI using HTTP and CDNI-specific Representation (draft-ma-cdni-
> capabilities-
> > 04)
> > -------------------------------------------------------------
> > This proposal is based on a CDNI-specific representation of footprints and
> > capabilities. Footprints and capabilities are encoded in JSON and
> transported
> > via HTTP.
> >
> > Stated objective is to distill dCDN resource knowledge into simple set of
> > capabilities and their footprints. That is, each capability has an associated
> > footprint.
> >
> > The draft defines the same basic set of capabilities as defined in the
> > requirements and provides some examples of their encoding.
> >
> > Each capability has a name, a list of values, and an optional list of footprints.
> > The list of values is specific to the capability name.
> >
> > The optional footprint list restricts its capability. Each footprint has a type,
> list
> > of values, and an optional mode. The list of values is specific to the
> footprint
> > type. A registry is defined for footprint types and includes country code, AS
> > number, and IP prefix.
> >
> > The footprint mode may be set to "replace", "include", or "exclude" which
> > indicates how the footprint should be treated with respect to "previous"
> > footprint information. In this context, "previous" refers to incremental
> > updates which are sent asynchronously from the dCDN to the uCDN. The
> > "replace" mode indicates that any previous information about the footprint
> > should be discarded and replaced entirely with the new information. The
> > "include" mode indicates an addition to the footprint while "exclude"
> > indications a subtraction.
> >
> > The draft does not provide a means for conveying footprint cost
> information.
> >
> > In practice, the dCDN FCI Server would return a full F&C document in
> > response to HTTP GET requests. An HTTP GET would be used to initialize
> the
> > state of the uCDN. In response to a GET, all modes are set to "replace".
> >
> > The proposal also allows the dCDN to send asynchronous HTTP POSTs to
> > uCDN for updating the F&C. Updates may use "include" and "exclude"
> > modes for partial updates. Each update includes a sequence numbers (via
> an
> > CDNI-FCI-seq HTTP header) in order to detect loss. Lost updates result in a
> > reset and a re-initialization.
> >
> > =======================================
> > Analysis
> > -------------------------------------------------------------
> >
> > Transport and Encoding: both proposals rely on HTTP transport and JSON
> > encoding. This is a good starting point and is in line with current CDNI WG
> > documents (e.g. triggers and metadata drafts).
> >
> > Data Representation: in the case of draft-seedorf, the existing ALTO
> > representations for network and property maps are leveraged. These data
> > structures clearly fit the CDNI use case and have the benefit of prior
> review.
> > In the case of draft-ma, a new CDNI-specific representation is defined.
> There
> > is no clear technical deficiency with either approach given that a newly
> > defined representation can be as flexible as needed and the ALTO
> > representation is generic enough to support the CDNI use case. Leveraging
> > an existing protocol has obvious advantages but it is unclear to me whether
> > or not adding a dependency on the ALTO WG will be problematic in any
> way.
> >
> > Hierarchy: in the case of draft-seedorf, footprints have capabilities. In the
> > case of draft-ma, capabilities have footprints. In the single CDN case,
> neither
> > option is deficient. In the cascaded CDN case, the draft-seedorf approach
> > seems more intuitive. Aggregated footprint and capability information is
> > constructed simply by appending the footprints of all dCDNs.
> >
> > Cost Information: in the case of draft-seedorf, a loose description is
> provided
> > of how to apply ALTO Cost Maps to footprints. In the case of draft-ma, no
> > solution is described. Cost information is only useful when multiple dCDNs
> > can claim the same end clients in their footprint advertisements. However,
> > regardless of the use case, business logic is likely to kick in before such cost
> > metrics would be useful. Neither approach includes a definitive proposal in
> > this area.
> >
> > Extensibility and Versioning: Versioning of the FCI protocol is not discussed
> > by either draft. Extensibility is alluded to and is clearly possible. However,
> the
> > details are lacking in this area.
> >
> > Dependence on ALTO WG: In the case of draft-seedorf, a dependency is
> > introduced on the ALTO WG and a few drafts in progress. In the case of
> draft-
> > ma, no such dependency is required. The benefits of leveraging ALTO
> include
> > the ability to easily reuse the work that the ALTO WG has done in
> hardening
> > the error handling, security, encoding, and processing of the ALTO protocol.
> > However, the difficulty of these efforts is not insurmountable and could be
> > reproduced in a CDNI-specific proposal.
> >
> > Capability Inheritance: in the case of draft-seedorf, the PID Property Map
> > defines rules for implicit inheritance between multiple overlapping PIDs. In
> > the case of draft-ma, no special inheritance rules exist. These inheritance
> > rules may complicate implementation of FCI. Completely explicit
> capabilities,
> > such as in draft-ma, may be a better approach.
> >
> > Update Notifications: in the case of draft-seedorf, no strong story for
> update
> > notifications is provided. The ALTO Incremental Updates draft is
> referenced.
> > However, this draft is expired. In the case of draft-ma, an HTTP POST may
> be
> > sent from dCDN to uCDN which includes the incremental update. Assuming
> > that update notifications is a real requirement, then draft-ma has a more
> > concrete approach in this area. However, a bidirectional HTTP interface
> > breaks the RESTful nature of the interface.
> >
> > Incremental Updates: in the case of draft-seedorf, the ALTO Incremental
> > Update draft is referenced. This draft describes the use of JSON Patch for
> > encoding incremental changes to ALTO information. Additionally, ALTO
> allows
> > for filtered queries which could be used for obtaining partial information. In
> > the case of draft-ma, a scheme including sequence numbers, a new HTTP
> > header, and a "mode" is used for conveying incremental changes via HTTP
> > POST. Like the update notifications, the draft-ma proposal is more concrete
> > in this area. However, again, the ALTO approach is more RESTful.
> Additionally,
> > adding a new HTTP header for this purpose may not be workable.
> >
> > Draft Maturity: both draft-seedorf and draft-ma require another level of
> > detail. Neither describe versioning and extensibility. Neither discuss the
> > encoding of logging and metadata capabilities which may pose significant
> > challenges.
> >
> > =======================================
> > Conclusion
> > -------------------------------------------------------------
> > All in all, both drafts are well-written and viable candidates as a starting
> point
> > for our FCI standard.
> >
> > I would suggest that the working group must first decide whether the
> > benefits of reusing the ALTO syntax and semantics outweigh the costs or if
> > defining something CDNI-specific is a better option. As far as I can tell, the
> > data representation defined by ALTO meets the needs of CDNI. My only
> > concern is a dependency on the progress of the ALTO WG. Starting with a
> > CDNI-specific representation provides maximum flexibility.
> >
> > I would also recommend that we first focus on a simple HTTP GET interface
> > and then, once stable, turn our attention to incremental updates.
> >
> > Cheers,
> > Matt
> >
> >
> > _______________________________________________
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> > [e-mail]
> > https://www.ietf.org/mailman/listinfo/cdni
> 
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