RE: Query re request routing

["Tomlinson, Gary" <gary.tomlinson@cacheflow.com>]

On Monday, March 05, 2001 @3:57 PM Phil Rzewski wrote:

>At 09:00 AM 3/5/01 +0000, Steve Rudkin wrote:
>> [Omitted text]
>>Whilst there is a need to interconnect distribution systems of the source
>>and destination CDNs (and any intermediaries) and to do the same for
>>accounting systems,  is it necessary for the RRS of the destination CDN to
>>interact with other RRSs? If so, why? If not, should the statement that
>>there is a single authoritative RRS for each *content unit* be
>>modified/qualified in some way. Would it be better to say there is a
single
>>authoritative RRS for each *request* ?

>I agree with this distinction. It's one of the types of things I am trying 
>to capture in Scenarios by enumerating something called an "Access Content 
>Network" (ACN).

>[Omitted text]

>There's still plenty of room for the CDI model we've worked with up until 
>today (that the Authoritative Request-Routing system, near the publisher, 
>has ultimate control). That's because there's going to be plenty of 
>Internet "edge" that won't be covered by avatars, but will be covered by 
>CDNs. There might be two CDNs with surrogates in that neighborhood, it's 
>just a case of choosing the "best" at that moment.

I need to clarify and reaffirm the requirement "Single AUTHORITATIVE
REQUEST-
ROUTING SYSTEM for PUBLISHER object URI name space".  What this means, is
there
only one authoritative party for the URI name space containing objects being
distributed.  All Content Networks in the distribution chain MUST have
authority to operate on the name space granted to them by this AUTHORITATIVE
REQUEST-ROUTING SYSTEM.  The granting of this authority is done via
delegation, which can be done either on-line via protocols or off-line via
SLAs or something contractually equivalent.  For the ACN model, in order for
ACN network elements to participate in the REQUEST-ROUTING SYSTEM, the ACN
must have received this delegated authority.  

That said, there are a couple of cases that come to mind here; 
1) ACN delivers the content acting as a SURROGATE; 
In this model, the ACN is peering {DISTRIBUTION & ACCOUNTING} with one or
more  CDNs to extend the reach to its own SURROGATES. Since is a priori
knows that it will be delivering from one of its own SURROGATES, it can
bypass the AUTHROITATIVE REQUEST-ROUTING SYSTEM and use its own internal
mechanisms to select the correct SURROGATE.

2) ACN delivers the CONTENT acting as a AVATAR;
In this model, the ACN is not peering with any CDN and simply providing
AVATAR services to its CLIENTS.  What this means is, the AVATARs are acting
as caching proxies, outside the transitive administrative domain scope of
ORIGINs and thus are not authorized to act in behalf of ORIGINs; which is to
say, they are not within the CDN distribution boundary.  Thus, the AVATARs
assume the CLIENT role as proxies and MUST use the AUTHORITATIVE
REQUEST-ROUTING SYSTEM to select the correct CDN SURROGATE for delivery of
content to the AVATAR.  Logically, the distribution from the ORIGINs point
of view has terminated at the SURROGATE and delivery has been performed to
the AVATAR acting as a CLIENT.

Gary