Re: Distribution CPG Protocol

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

Alex French wrote:

> Phil,
>
> I agree with your mail. QoS is pretty hard to enforce in this case -- if we
> allow surrogates to advertise things like "bandwidth", "latency", etc, I
> can see some major abuse happening if a spot market ever develops.
>
> There is one QOS-like parameter that I think *should* be included: disk
> space. This is perhaps something that the Content Provider needs to
> advertise, and the surrogate accept. I.e., the Content Provider should say
> "I have site x, and it uses 3G". The peer CDN can use this info to allocate
> resources, even if it does not pull (or allow to be pushed) the whole site
> up front.
>
> As for surrogates advertising their connectivity, proximity, etc, I don't
> think this is possible to do in a way that can be autonegotiated (unless we
> get the AI guys on board...). I would prefer to see this done offline, by
> humans.
>
> The only other thing that should go into the protocol, IMHO, is negotiation
> of the actual distribution method. One CDN might allow push and pull to
> prepopulate surrogates, another may only allow pull, and some may decide
> not to prepopulate surrogates at all, and do it on demand. All three of
> these scenarios need to be negotiated, and the Content Provider's system
> may need to modify access rules, etc, for all three scenarios.
>
> At its most basic form, therefore, I see the distribution protocol consiting of
>
> 1- Handshake when peering is (manually) set up
> 2- Content provider sending advertisements of the form
>          <URI_REGEXP>, <DISKSPACE>
> 3- Peer CPG sending
>          <REJECT> [MAX_SPACE] | <ACCEPT>, <[push] [pull] [on-demand]>
> 4- Content provider acks one or more methods or sends <REJECT>
> 5- Exchange of authentication data to be used to transfer content
>

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.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.

Kobus