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

["Dmitri Krioukov" <dima@krioukov.net>]

Has the IETF started voting? -- 1 :)

I missed the point when the metric was dismissed, though :(

Another thing is what work is being done -- on requirements
(loop free) or on methods/protocols (options below)? Anyway,
restriction of topology goes well beyond both up to the
inter-CDN architecture.
--
dima.

> -----Original Message-----
> From: owner-cdn@ops.ietf.org [mailto:owner-cdn@ops.ietf.org]On Behalf Of
> Oliver Spatscheck
> Sent: Tuesday, April 03, 2001 5:12 PM
> To: cdn@ops.ietf.org
> Subject: Executive summary of: RE: hard questions: request routing
>
>
>
> Enclosed the executive summary of the discussion about loop avoidance in
> request routing. I think I finally understood Abbie's solution
> after talking
> to him and we think it is time that the group agrees which method
> we should use
> to move on. The candidates which crystallized so far:
>
>
> 1. Restrict the topology.
>
>    This solution statically restricts the depth of request
> routing to one (or
>    maybe two). This avoids loops due to its static limitation,
> however, it is
>    the most restrictive one. On the other hand the protcol
> overhead is zero.
>
> 2. Recursive request routing
>
>    The request is handled by the first CDN contacted by a client.  The CDN
>    will ask other CDN's recursively to resolve to an A record.
> This recursive
>    request includes a request path which can be used to prevent
> loops. This
>    avoids the DNS hack issue, however, it requires a new protocol (or DNS
>    extension) to carry the path information.
>
> 3. Abbie's proposal
>
>    A matrix is distributed to all participants representing the
> relationships
>    between individual CDNs for a particular set of content.  This
> matrix is
>    used to encode the path info as set of CNAMEs in a structured
> way. So this
>    solution is similar to Brad's suggestion, except it adds
> structure to the
>    CNAME encoding (see Abbie's email for more data).
>
> 4. Abbie's proposal as I understood it first..... .
>
>    A cycle free graph is generated based on the matrix every time
> a CDN starts
>    or stops serving a particular set of content. This cycle free graph is
>    distributed to all CDN's involved atomically. Request routing is now a
>    traversal of this cycle free graph. This is basically a
> variant of a link
>    state protocol, but the atomic requirement makes it rather expensive.
>
>
> I think we discarded already the path vector with common metric
> approach. So at this point we have to decide which way we want
> to go. PLEASE VOTE NOW!
>
> Oliver