Re: [babel] Warren Kumari's No Objection on draft-ietf-babel-v4viav6-07: (with COMMENT)

[Warren Kumari <[e-mail]>]

On Thu, Feb 17, 2022 at 12:13 PM Juliusz Chroboczek <[e-mail]> wrote:

> > Is it *always* safe for a babel router to ignore a route? I really
> haven't
> > thought about it enough (and the fact that it is DV based makes me think
> that
> > it should be fine) but I'd like some reassurance that it is, especially
> in the
> > case that a prefix is originated by multiple routers, and one of them
> gets
> > filtered/ignored.
>
> (I assume that by "safe" you mean "preserves Babel's loop-avoidance
> properties".)
>

Yup!


>
> Yes, dropping updates preserves Babel's loop-avoidance properties.  The
> proof of the loop-avoidance properties of Babel never assumes that
> a packet cannot be repeatedly lost (it only relies on the hypothesis that
> a packet is never received before it is sent, i.e. that the happens-before
> relation is acyclic).
>

Awesome, thank you.

An intuition that some people have found useful is that Babel is based on
> principles similar to BGP: if something is trivial in BGP, then it's
> probably easy in Babel; if something is tricky in BGP, then it's difficult
> or impossible in Babel (for example, we don't know how to do aggregation
> in Babel, since it's not clear how to map an AS-Set to a Babel feasibility
> distance).
>

Excellent, thank you -- that's a helpful bit of intuition / analogy  /
comparison / $something to know.
W


>
> -- Juliusz
>


-- 
The computing scientist’s main challenge is not to get confused by the
complexities of his own making.
  -- E. W. Dijkstra