Re: Distribution CPG Protocol - Some Thoughts

[brad cain <bcain@mediaone.net>]

Alex French wrote:
> 
> I think we may be straying into a discussion of the content routing system
> rather than the content distribution peering; valid discussion, but we need
> to be clear which problem we're dealing with.

I think there is confusion as to where the content specific
information needs to be exchanged in the model.  I believe
that in all three types of peering this needs to occur.  

Here's a summary:

[note: i'm using the term "content exchange protocol" to
refer to a generic protocol which exchanges information
about a specific URI]

Direction Peering: Requires a content exchange protocol to
exchange information regarding
	1. Where the content is located
	2. Metrics related to surrogate/CDN selection
	3. Other metrics related to load, etc

Distribution Peering: Requires a content exchange protocol
for:
	1. Exchanging content which should be pushed
	into surrogates
	2. Real time content signals (this is probably
	a separate protocol)

Accounting Peering: Requires a content exchange protocol
for:
	1. Exchanging sets of URIs which a given CDN is
	authoritative for so that logging and billing
	information can be aggregated back toward the
	authorititative entity


It seems as if all three of these cases need a protocol
which does a quick handshake and then exchanges:
	URI #1, Attribute #1, Attribute #2
	URI #2, Attribute #1, Attribute #3
	etc

The requirements in all cases are:
	1. Secure point-to-point protocol (i.e. TCP with
	IPSec)
	2. Capability negotiation
	3. Ability to prevent advertisements from looping
	4. Extensible for adding new attributes to content



-brad