Re: Distribution CPG Protocol

[Kobus van der Merwe <kobus@research.att.com>]

Alex French wrote:

> At 03:22 PM 10/01/2001, Kobus van der Merwe wrote:
> >I was thinking the order should be the other way around:
> >1) handshake
> >2) CPG advertise peer CDN capabilities (space, distribution methods supported)
> >3) Content provider sends content advertisement
> >4) CPG accepts or rejects
> >etc
>
> I don't know if CDN operators would want to advertise their total available
> space. In any case, this is likely to be governed by offline policy
> decisions, e.g. a contractual agreement that I will provide you with 3G per
> site for 10 sites. The protocol would need to know what the sites were
> before it could advertise the space available to them, which is similar to
> what I suggested.

The capacity advertised to a peer would reflect the capacity available
to the peer based on some contractual agreement (not the total capacity
of the CDN). Furthermore this advertisement should be per region
which could again be based on an off-line negotiated contract.

>
> >I.e. a content provider should decide how it wants its content to be
> >served and choose a CDN with the appropriate capabilities then
> >advertise to it.
>
> I would agree with those who have suggested that a CDN is (more or less) a
> black box as viewed from other CDNs. QoS is too hard to negotiate
> online.Apart from space, what other parameters would you say govern how the
> content is served?
>

I agree that internal details of a CDN should not be exposed. However, I don't
think treating a CDN as a complete black box is viable. We have to somehow
be able to distinguish between a CDN with local vs global footprint. And
this is I think what regions are giving us. Then I would like to see capacity
used (storage and bandwidth) per region advertised to a peering CDN
(on minutes timescale).  Negotiation of the total capacity available to a
particular
peer might well be done through off-line negotiation but feedback of actual
usage needs to be in real time (minutes).

Also, for some content (e.g. streaming) I might want to only use CDNs
that can handle push. Whereas for other content it might not matter.

Kobus

>
> --
> Alex French
> Consultant, Technical Services                     E: afrench@vianetworks.com
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