Re: [Idr] WG LC on draft-ietf-idr-rpd-05.txt (7/15 to 7/29/2020)

[Ignas Bagdonas <[e-mail]>]

Hi there,

This document seems to propose something that has a substantial disconnect
with operational aspects of practical networks. Routing policy is not an
unordered set of prefixes, attributes, and actions, it is strictly ordered,
and ordered nontrivially based on the intended outcome of that policy, and
not based on some standalone sorting property of separate policy elements.
It is not enough to advertise a policy entry to a node, it needs to be
inserted into a specific place in the policy. For the case of Flowspec it
works fine as filtering eventually is based on a longest prefix and that is
an implied sorting property, whereas routing policy in a general case is
not. BGP is unidirectional, and a fact that an update is received by a
remote node does not imply that the policy change is applied and it is not
known when it is applied. Without a feedback mechanism there is no way to
have a consistent policy within a node, and also no way to have a
consistent policy across a set of nodes. Routing policy information is not
necessarily a very public type of information, and an overall approach of
distributing it as wide as possible and then trying to limit and segregate
it for intended recipients is just not practical.

The fact that Flowspec can do something and it works does not mean that
functionality that has inherently different applicability and different
propagation properties should use that same model. Routing policy is a
configuration level construct, and there are no principal obstacles in the
field for dynamic policy modifications. For controlled policy adjustments
there are existing point to point BGP signalling mechanisms that could be
more suitable if a configuration based mechanism is not enough.

The major problem with progressing this document in the form it is now is a
message to the operations community that IDR is quite disconnected from the
problems and realities of the field. Vendors certainly can implement any
functionality they see fit and it is for the market to decide, RFCs are not
needed for that.

For specific answers to WGLC questions:

> 1) Do you feel this draft has an solution that is acceptable With the IPR
as a WG RFC?

No. It is not evident that the problem itself is clear, or exists at all in
a form as stated, it is not evident that the proposed mechanism was
socialized with the operations community for a feedback, and it is not
evident that the proposed solution fits into the operational practices as
seen in the field.



> 2) Do you feel this draft is ready to publish?

Not at all. There is little content in the document, it is underspecified
for being suitable for an interoperable implementation, and a larger part
of it is a compilation and a plain copy of fragments from other documents.


> 3) Do you know of implementations of this draft?

No.



> 4) Do you know of deployments of this draft? If so, is this feature
useful in the deployments.

Not aware of any deployments. Whether such functionality might be of use
for deployments is best to be queried in operational communities.


> 5) Do you feel that Wide Communities is ready for Publication?

Possibly, although wide communities is a completely separate document, and
the fact that -rpd- document uses wide communities as a transport container
does not imply that one or the other are ready because of that. Those
should be two separate WGLCs.

Ignas



On Wed, Jul 15, 2020 at 2:11 PM Susan Hares <[e-mail]> wrote:

> This begins a 2 week WG LC on draft-ietf-idr-rpd
>
> from 7/15 to 7/29/2020.  You can obtain this draft at:
>
> https://datatracker.ietf.org/doc/draft-ietf-idr-rpd/
>
>
>
> This draft defines a new AFI/SAFI and new atoms
>
> for the Wide Communities.  This WG LC has been delayed
>
> as I waited for a resubmission of the Wide Communities draft.
>
> I had hoped to do these 2 WG LC in parallel.
>
>
>
> I’ve not received the Wide Communities draft, but we will
>
> start this WGLC to provide feedback to the authors.
>
> We may have to run a short follow-up to this WG LC
>
> If there are changes to the Wide Communities draft during
>
> Its WG LC.
>
>
>
> There is an IPR statement on this draft.
>
>
>
> In your responses please answer the following questions:
>
>
>
> 1) Do you feel this draft has an solution that is acceptable
>
>    With the IPR as a WG RFC?
>
>
>
> 2) Do you feel this draft is ready to publish?
>
>
>
> 3) Do you know of implementations of this draft?
>
>
>
> 4) Do you know of deployments of this draft?
>
> If so, is this feature useful in the deploy ments.
>
>
>
> 5) Do you feel that Wide Communities is ready for
>
> Publication?
>
>
>
> Cheerily, Susan Hares
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