Re: [CDNi] New Internet Draft: draft-sopher-cdni-footprint-types-extensions

[Kevin Ma <[e-mail]>]

Hi All,

  It's been a while since we had the FCI debates, and FCI has a rather
complex history, so I've had to refresh my memory.

  wrt the text in question: "Multiple footprint constraints are additive:
the advertisement of different footprint types narrows the dCDN's candidacy
cumulatively." I believe that statement was referring to if multiple FCI
messages were sent for the same capability but the messages had different
footprints in them; I do not believe it was intended to apply to multiple
footprints in the same message.  (I believe it stemmed from a protocol
implementation question for how to override footprints and how to deal with
footprints in sequential messages, which I had addressed in my original
capabilities protocol draft:
https://tools.ietf.org/html/draft-ma-cdni-capabilities-04#section-2 and
https://tools.ietf.org/html/draft-ma-cdni-capabilities-04#section-3.2 .)

  In addition, I don't know that we should give any normative weight to a
non-normative statement in an appendix.  As the draft points out (
https://tools.ietf.org/html/draft-sopher-cdni-footprint-types-extensions-01#section-2.1
), applying the statement to the list of footprints in a single message
produces an absurd result (i.e., disjoint footprints produce an empty set
of footprints), and that was certainly not the intention (which I think we
can infer from the prevention of such a result in the protocol drafts).

> Frankly, this is very strange that the statement is almost hidden in a
kind of annex  whereas it could have been located in section 5 in a proper
dedicated section.

  Coming out of IETF 90 and 91, we had decided to focus the FCI semantics
draft on just the information that needed to be advertised and separate out
the protocol specifications (see:
https://mailarchive.ietf.org/arch/msg/cdni/3GVjUbBNsf2gV8fQUhcVBRID_mU/ ).
All of the less relevant material was moved to appendices (per:
https://mailarchive.ietf.org/arch/msg/cdni/2gLvfnlbpJjIo57bER72kIiSZsk/ ).
In hindsight we probably could've done more to clean up the appendices, but
as is always the case, we did not have the benefit of hindsight at the
time.  The decision was made to rely on ALTO as a transport protocol, which
defines its own footprint type and enforcement rules (see:
https://tools.ietf.org/html/draft-ietf-alto-cdni-request-routing-alto-14#section-4.1
).

  We probably also could have done more to specify the interpretation of
the footprint list, but I think that was just delegated to the protocol
specs.  At the time, there was contentious debate between advertising of
footprints vs advertising of capabilities (thus:
https://tools.ietf.org/html/rfc8008#section-3 ), and our focus was
clarifying the advertisement of capabilities with footprint restrictions
and completing the semantics draft so we could move forward with the
protocol draft(s).

  If folks feel strongly about the appendix being confusing, we could
consider filing an errata?

Sanjay/Nir,

  If we disregard the statement in the appendix and assume that within a
single message, multiple footprint types are allowed and are considered as
a set, does that negate the need for the proposed ipv4v6cidr footprint type?

  wrt the iso3166code footprint type, I don't see any issue with it if
folks feel it would be useful.

thanx!

--  Kevin J. Ma

On Sun, Jan 10, 2021 at 5:54 PM Guillaume Bichot <
[e-mail]> wrote:

> Hi Sanjay & Nir.
>
>
>
> Here is the  statement from 8008 (Appendix B) : Multiple footprint constraints are additive: the advertisement of different footprint types narrows the dCDN's candidacy cumulatively.
>
> Frankly, this is very strange that the statement is almost hidden in a kind of annex  whereas it could have been located in section 5 in a proper dedicated section.
>
> Your proposal solves the issue but not completely. I guess nothing prevent me to add several footprint constraints of the same type like the example below. Strictly speaking, if I captured well that statement, we should end up with an empty list as well.
>
>
>
> {
>
>      "capabilities": [
>
>        {
>
>          "capability-type": <CDNI capability object type>,
>
>          "capability-value": <CDNI capability object>,
>
>          },
>
>          "footprints": [
>
>              {
>
>                  "footprint-type": "ipv4cidr",
>
>                  "footprint-value": ["192.0.20/24"].
>
>              },
>
>              {
>
>                  "footprint-type": "ipv4cidr",
>
>                  "footprint-value": [["192.0.21/24"]
>
>              }
>
>          ]
>
>        }
>
>      ]
>
>    }
>
>
>
> I have another proposal  that is the following: instead of creating a new footprint type that requires a change in RFC8006 as well, why not just changing that statement that looks strange and almost faulty.
>
>
>
> -remove that faulty statement in Appendix B.
>
> - create a new section 5.x about “footprints” and add a new statement (or just add that new statement in Appendix B) like the following:
>
> ”Several footprint constraints can be given of either the same type or not.   The uCDN MUST consider the resulting footprint as a set of geographical areas constrained with a set of IP address ranges if any. If several geographical areas overlap then the coverage zone corresponds to the cumulative areas.”
>
>
>
> Examples
>
> -          E1: a set of address ranges
>
> "ipv4cidr", ["192.0.2.0/24", “192.0.2.1/24”]
>
> “ipv4cidr”, [“192.0.2.2/28”]
>
> "ipv6cidr", ["2001:db8::/32"]
>
> -          E2: a set of geographical areas
> "iso3166code", ["ca", us-ny]
>
> -          E3: a mixed of geographical areas and address ranges
>
> "ipv4cidr", ["192.0.2.0/24"]
>
> "ipv6cidr", ["2001:db8::/32"]
>
> -          "iso3166code", ["ca", “us-ny”]
>
>
>
> Guillaume
>
>
>
> *Guillaume BICHOT, **Principal Engineer, Head of Exploration*
>
> [phone] | [e-mail]
>
>
>
>
>
> *From:* CDNi [mailto:[e-mail] <[e-mail]>] *On
> Behalf Of *Nir Sopher
> *Sent:* Wednesday, December 23, 2020 6:19 PM
> *To:* [e-mail]
> *Subject:* [E] [CDNi] New Internet Draft:
> draft-sopher-cdni-footprint-types-extensions
>
>
>
> Hi,
>
>
>
> We have submitted draft-sopher-cdni-footprint-types-extensions
> <https://eur02.safelinks.protection.outlook.com/?url=https%3A%2F%2Furldefense.proofpoint.com%2Fv2%2Furl%3Fu%3Dhttps-3A__datatracker.ietf.org_doc_draft-2Dsopher-2Dcdni-2Dfootprint-2Dtypes-2Dextensions_%26d%3DDwMFaQ%26c%3DudBTRvFvXC5Dhqg7UHpJlPps3mZ3LRxpb6__0PomBTQ%26r%3DXniVbishGiO2Ao9hKqSc-hTVIWCi3T-x6GdHR4ZTgoM%26m%3DTs5uj_nZmoHgi7pPldjWKsDPgmeeiO_RkotsI8zZD-E%26s%3DoWZZ4TjWJsq7Ao899RmyOUwUgAjNYeVlksfkKAy-UeA%26e%3D&data=04%7C01%7Cguillaume.bichot%40broadpeak.tv%7Cf6b67a86cc4b44ff6b7a08d8a83b82a1%7C0ebe44eac9c9438da0407e699f358ed4%7C0%7C0%7C637444320869999346%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=YxIzX3bst5GAicrOxFI%2BqfRZYO65%2Fwh07pDTwoYrrJg%3D&reserved=0>
> that extends RFCs 8006/8008 in order to address the following issue:
>
>    - Sections 4.3.5 and 4.3.6 of [RFC8006] specify the "IPv4CIDR" and
>    "IPv6CIDR" footprint types, respectively, for listing IP addresses blocks.
>    Using Footprint Objects of these types, one can define an FCI Capability
>    Advertisement Object footprint constraints that match IPv4 or IPv6 clients.
>    Also as described in section 5 of RFC 8008, the FCI
>    Capability Advertisement Object includes an array of such CDNI Footprint
>    Objects. The array of Footprint Objects has a "narrowing" semantic that
>    prevents the usage of IPv4/IPv6 objects together in order to create a
>    footprint constraint that matches IPv4 clients together with IPv6 clients.
>
>
>
> In the submitted draft:
>
>    1. We add a new usecase of dCDN advertising a footprint that consists
>    of both IPv4 and IPv6 client addresses, by defining a new "IPv4v6CIDR"
>    Footprint Type.
>    2. We also add support for ISO3166Code Footprint Type, based on ISO
>    3166 country codes and regions definition. This Footprint Type allows the
>    dCDN to advertise a footprint based on a specific region, for example a
>    state in the USA.
>
> We would highly appreciate it if folks can review and provide any feedback.
>
>
>
> Thanks and Happy Holidays,
>
> Sanjay & Nir
>
>
>
>
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