Re: Distribution CPG Protocol - Some Thoughts

[Martin May <Martin.May@activia.net>]

Oliver Spatscheck wrote:

> As of Gary's other comments and my follow up it seems still open if
> the content gateway or accounting gateway will provide this information.
> I would like to hear from more people how they feel about this.
> I think this decision is very important in our design in that
> we don't need a BGP like interface for the CPG if all information
> is gathered by the accounting system. In this case we know which CDNs
> will be used a priory and all we have to do is to inform them
> where to fetch content. We don't have to advertise the content to all
> CDNs (or surrogates as originally proposed).
>
> Anyway I think a total aggregate is not good enough. We have to be able
> to identify regions (or ASs or whatever else we call it). I think the
> case in which two CDNs are in the same region (from a network perspective)
> and the redirection system has to decide which one to use is an
> important one we have to address. It also is a open question if we
> should inform a CDN in the CPG that clients in some regions will
> not use its service or let the CDN figure that out by itself.

I agree with Oliver that we have to be able to address some specific
regions
inside each CDN. National content providers (e.g. in europe or asia)
want to
distribute their content only nationwide. Hence, without the notion of
regions, an
internationally acting CDN is not very suitable or probably too
expensive.
(here, region implied geographic region but can be replaced any other
definition such as "subset of surrogates").
Legal limitations should be also considered. It might be illegal to
distribute
content in countries like China or Iraq. We need mechanisms to exclude
these surrogates from the distribution.

>
>
> Overall it is a fine balance between allowing a CDN to manage/operate
> its surrogates by itself and to gather enough detailed information
> on the gateways to make any intelligent decision. I don't
> think a single number for all surrogates per CDN will cut it. I also
> agree that information on a per surrogate basis while desirable
> is probably unrealistic. However, aggregated information for
> meaningful network regions seems like a reasonable approach to me.

regional does not mean that we have to be able to address each
surrogate.
Each CDN can define the regions (I prefer the term footprint or subset
of
surrogates) that it can serve.
I prefer a model where a CDN first advertises its surrogates/footprints
and then the CP advertises the content to the subset (follow Olivers
proposal).
  > >PhaseI: the surrogates (or groups of surrogates) advertise
themselves
  > >         to the content provider.
  > >PhaseII: the content provider advertises the content to a subset of
  > >         surrogates.
  > >PhaseIII: the surrogates accept


Martin

>
>
> Oliver