Re: [Sidrops] Robert Wilton's No Objection on draft-ietf-sidrops-rpkimaxlen-15: (with COMMENT)

[Ben Maddison <[e-mail]>]

Hi Robert,

Thanks for making the time to review.
Some thoughts below...

On 08/15, Robert Wilton via Datatracker wrote:
> I considered balloting this as a discuss (for a discussion), but this is
> outside my area of knowledge expertise.
> 
> Although the document indicates that the number of published ROAs should remain
> the same, since each ROA can list multiple prefixes, was any consideration to
> the potential increase in VRPs (if that is the right term) that this change
> will cause and whether this may negatively affect routers that are consuming
> the ROAs/VRPs?

I don't recall this coming up in the wider WG, but it was discussed
initially between the authors.

The consensus from that conversation was that, whilst your observation is
quite correct, the ability of the "global" VRP set to scale to DFZ-like
size is necessary for ROV to be successful in the long term, and that
this scaling requirement ought not to be met by sacrificing the
effectiveness of its protections.

I am not aware of any implementors having indicated that the
recommendations in the draft would pose a scale challenge if fully
implemented.

If a scaling problem presents in future, my best guess is that it comes
at the router-policy-evaluation layer (since bandwidth and cycles at the
RP are ~cheap). All the "serious" BGP implementations that I am familiar
with have solved the problem of efficiently applying large prefix-list
policies - of which ROV-policy is really just a variant. All said: I am
pretty sanguine about this!

Let me know if you think any of this needs to be in the draft itself? It
feels more like a topic for a different document to me.

> Am I right in assuming that the number of valid ROAs that can be announced
> should effectively be bound by the number of BGP prefixes advertised for an AS
> and hence this shouldn't be a problem?

That's true, but since de-aggregation continues a-pace, it's not a very
firm bound; it's not what I am betting on to allow us to scale.

> But other that the question above, I found this document to be very easy and
> pleasant to read.

Thanks, much appreciated.

Cheers,

Ben