Re: [Idr] IDR interim 25 September, -car type 2 - split to separate document?

[Jeffrey Haas <[e-mail]>]

Robert,


> On Sep 25, 2023, at 2:26 PM, Robert Raszuk <[e-mail]> wrote:
> As you recall, the ability to aggregate routes is a very important feature in any design. And the less we carry in the protocol the better. 

Aggregation is possible in type 1.

If aggregation is the only purpose for type 2 (I don't believe it is), that needs to be called out.

Minimally, clarity is needed for when type 1 and type 2 are used, especially when type 2 with LCM appears to be functionally identical to type 1 routes.  Implementations need to know when installing forwarding state, or doing resolution prioritization between route types what the intended semantics are.  This gets even messier in circumstances where route redistribution is intentionally done by the operator.

> 
> Then last to me Type 2 is the proposal which addresses many previous attempts to define separate next-hop SAFI (Ilya and I had one such attempt: https://datatracker.ietf.org/doc/html/draft-ietf-idr-bgp-nh-cost-01 <https://datatracker.ietf.org/doc/html/draft-ietf-idr-bgp-nh-cost-01>)  and as I recall we were not alone in trying to define it. 

This broadens the scope from color aware routing even past the "for srv6" justification.

> 
> As DJ reiterated today the entire idea behind CAR is to have easily extensible SAFI to carry various infrastructure routes. I am not sure what value is in splitting the document now other then just to delay the progress. This is specifically considering experimental nature of the draft where the bar by design is not as high as for standards track docs. 

Minimally, we got through a few years of process covering just type 1 for color-aware use cases.  Type 2 shows up literally at WGLC time.

Is it fundamentally necessary?  Perhaps.  The requested clarifications will help address this.

Is it scope creep, but desired scope creep?  Then it likely will push out the RFC publication time as we go through similar review for the new functionality. If it's not fundamental and it's important to ship -car type 1, splitting it out as an extension is an easy option.

If the authors want to go through similar review effort and reset the clock for type-3, type-4, etc. at a later date if the WG decides the scope creep is appropriate - so be it. 

-- Jeff