Re: Distribution CPG Protocol - Some Thoughts

[Oliver Spatscheck <spatsch@research.att.com>]

Stephen Thomas writes:
 > At 12:26 PM 2001-01-05 -0500, brad cain wrote:
 > > >Proposal 1: The protocol should advertise the availability of content.
 > >
 > >I partially agree with this design decision... However, I also
 > >believe that MINIMAL surrogate information should also be passed
 > >between CDNs with a very simple metric.  Let me explain:
 > >
 > >Advertising surrogates is problematic for the following reasons:
 > >         1. CDNs don't want to share intimate knowledge of their
 > >         networks (and this is coming from someone who used to work
 > >         for one).
 > >         2. Exchanging meaningful QoS between providers has proven
 > >         in other worlds (i.e. layer-3) to be extremely difficult.
 > >         This is why I propose a very generic metric that would be
 > >         CDN to CDN specific.
 > >         3. Treating CDNs as a "black box" for now is the most
 > >         pragmatic approach and one that I believe is necessary
 > >         to get something started.  Enhancements can be made
 > >         later as necessary (analogy: inter-provider diff-serv).
 > >
 > >However, I do think that advertising a tiny bit of surrogate
 > >information is useful.  My proposal is to advertise IP prefixes
 > >with a generic metric between providers.  This proposal isn't
 > >geared at "classic cdns" (i.e. akamai) because they are complete
 > >Internet overlays.  It is intended for ISPs who deploy their
 > >own CDNs and want to advertise POPs that have surrogates.
 > 
 > I'm rapidly turning into a broken record, here, (and I'll really try to 
 > shut up on this), but it is necessary for CDNs to advertise prefixes, or 
 > can a CDN just post its list on its Web site? Potential customers (or 
 > peering partners) have a look at this list before they sign up with the 
 > CDN. I'm not trying to be a pest because I have any particular notion of 
 > what the market will or will not accept. I'm just trying to push back on 
 > anything that might complicate the initial protocol. (And I am only 
 > worrying about the initial protocol; there's always ng, or, as folks have 
 > taken to lately, bis.)
 > 
 
Actually if you look at the CDN peering document Fred emailed out a while back
you will see that we use a Web based protocol to get this information.
However, it is important for us to get this information in pseudo real time.
Surrogates for particular regions break, surrogates for particular regions are
added, surrogates for particular regions are overloaded this are all events
the other CDN has to know about. You can't expect a CDN to gather this
information by hiring somebody who constantly looks at the other CDNs Web
page. There has to be some standard and automation here. As I stated by now
also to many times I am not sure anymore if the right place to gather this
information is the distribution part of the architecture. I would really like
to know what other people think about it.

Oliver