Re: [Anima] Review draft-ietf-anima-reference-model-04

[Brian E Carpenter <[e-mail]>]

Artur,

Thanks for your review. Whoever takes up the editing pen next will certainly use your comments.

On one specific point:

> c) Later, the text in this section somehow confuses the high level requirements (=information distribution) with a specific implementation, notably flooding. Note that there is a subtle difference between the requirement to reach all recipients (indeed, the current text seems to equal flooding to that) and flooding, which technically usually means "unconstrained broadcast". [E.g. Wikipedia: "Flooding is a simple computer network routing algorithm in which every incoming packet is sent through every outgoing link except the one it arrived on"]. This will lead to explosive message number growth, as the ACP uses routing - which does not guarantee a tree structure - while the scale of an autonomic domain is, by definitions of RFC7575, only constrained by the Intent as such ("the autonomic domain is the set of nodes, to which the intent needs to be sent"). At the same time, there are better known algorithms for routing, which achieve "distribution to all recipients" without "sending on all links except the one it arrived on" (e.g. structured broadcast, etc).

I agree in general; the way the text uses "flood" is careless. However, the GRASP flooding mechanism is (a) of course limited to GRASP nodes and (b) contains specific measures to prune the distribution and prevent loops. While
that does not guarantee a strict tree structure, i.e. is not an idealised multicast routing algorithm, it doesn't require the ACP to support multicast routing and it is well adapted to low-frequency information distribution as we expect in an AN. 

Regards
   Brian