Re: [Idr] AD Review of draft-ietf-idr-bgp-bestpath-selection-criteria-12

[Alvaro Retana <[e-mail]>]

On May 4, 2020 at 2:10:14 PM, Rajiv Asati (rajiva) wrote:

[Explicitly adding draft-ietf-idr-tunnel-encaps to the distribution.]


Rajiv:

Hi!


> Thanks, Alvaro. While it would have been preferred to keep the (NH selection
> / verification) logic independent, it seems that there may perhaps be the
> following 2 means to solidify the logic -
>
> a- Tunnel Encapsulation Attribute (updating rfc5512)
> b- Cost Community
>
> It seems that (a) is somewhat more progressive than (b), and clearly conveys
> the encap preference that can be leveraged. Thoughts?
>
> If agreed, then section 3 could be updated to reflect something akin to the
> following -
...


As a matter of fact, §5 of draft-ietf-idr-tunnel-encaps lists

   *  The tunnel is specified in a TLV whose Tunnel Endpoint sub-TLV
      identifies an IP address that is reachable.

...as a condition for the tunnel to be considered feasible.  In my
review of that document [1] I wrote this:

   [major] How is reachability determined?  Where (which table) should
   the address be looked up in?  In the sequence above, the destination
   address of P and the address of the endpoint may be resolvable in
   different tables...

   [BTW, please also take a look at
   draft-ietf-idr-bgp-bestpath-selection-criteria, which I think tries to
   define a related, if not the same, concept.]


I think this is a good time for you and the authors of
draft-ietf-idr-tunnel-encaps to talk.


Thanks!

Alvaro.


[1] https://mailarchive.ietf.org/arch/msg/idr/S1nyz1sewA_Xqf63W_vz8c4L8Z0/