Re: Distribution CPG Protocol

[Alex French <afrench@vianetworks.com>]

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

That's absolutely minimal, I would say...

At 04:33 AM 10/01/2001, Phil Rzewski wrote:
>What would a "policy-based best-effort" system look like for Content 
>Distribution Internetworking?

--
Alex French
Consultant, Technical Services                     E: afrench@vianetworks.com
VIA NET.WORKS, Inc.                                T: +353 (86) 818 8118
12100 Sunset Hills Rd, Reston VA 20190      F: +353 (865) 818 8118