RE: Executive summary of: RE: hard questions: request routing

[DonE@activate.net]

> -----Original Message-----
> From: Francis Zane [mailto:francis@research.bell-labs.com]
> Sent: Wednesday, April 04, 2001 11:17 AM
> To: Cain, Brad
> Cc: 'Oliver Spatscheck'; cdn@ops.ietf.org
> Subject: Re: Executive summary of: RE: hard questions: 
> request routing 
> 
> 
> 
> Regarding the proposed solutions, I'm agnostic among solutions which
> don't do forwarding within the RRS.  I can see cases where small
> amounts of forwarding (eg, limited depth, or one-way between certain
> classes) could be quite useful, and so I'm happy to explore that as
> well.  I'm just very nervous about schemes that allow forwarding in
> its complete generality.
> 
> I very much like Brad's suggestions, though I would also support
> allowing some other trivially-safe cases.  For example, having some
> nodes identified as only outgoing or only incoming with forwarding
> allowed in the appropriate direction would handle Oliver's situation
> with many ISP destinations, but still be safe.  On the other hand,
> that proposal seems like (1) or (2), while leaving the door open for
> future development of forwarding, so maybe I'm not understanding the
> distinctions between all the cases.
> 
> My main concern with fully general forwarding mechanisms remains the
> ability to deal with different (particularly non-DNS) RRS mechanisms
> and all the cases which could arise.  As a (mostly thought-experiment)
> example, here's a weird case that concerns me: Suppose I have an RRS
> which spans two specific RR mechanisms: DNS (based on local DNS IP)
> and some form of L7 (based on client IP).  Is there a way to guarantee
> correct (ie, non-looping) behaviour?  (CDN A DNS redirects to CDN B
> based on local DNS, which HTTP redirects to CDN A based on client IP).

It sounds like you are talking about the intra-CDN RRSs.  The inter-CDN RRS
would be either DNS-based or L7-based.  The possibility of using them both
for inter-CDN RRS is not clear to me, but possibly something like DNS-based
RRS used for footprint and Internet distance metrics and L7-based RRS used
for load metrics.

Don

> Francis
> 
>