Dear Alberto and authors
Thank you for the good work on this doc. I fully support moving this
document as a proposed standard, however I have a few comments on the
document. See PPE below
1. Introduction
<...>
In general, when an ITR/RTR/PITR wants to be notified for mapping
changes for a given EID-prefix, the following steps occur:
(1) The ITR/RTR/PITR sends a Map-Request for that EID-prefix.
(2) The ITR/RTR/PITR sets the Notification-Requested bit (N-bit) on
the Map-Request and includes its xTR-ID and Site-ID.
(3) The Map-Request is forwarded to one of the Map-Servers that the
EID-prefix is registered to.
(4) The Map-Server creates subscription state for the ITR/RTR/PITR
on the EID-prefix.
(5) The Map-Server sends a Map-Notify to the ITR/RTR/PITR to
acknowledge the successful subscription.
(6) When there is a change in the mapping of the EID-Prefix, the
Map-Server sends a Map-Notify message to each ITR/RTR/PITR in
the subscription list.
(7) Each ITR/RTR/PITR sends a Map-Notify-Ack to acknowledge the
received Map-Notify.
This operation is repeated for all EID-prefixes for which ITR/RTR/
PITR want to be notified. The ITR/RTR/PITR can set the N-bit for
several EID-prefixes within a single Map-Request.
<...>
PPE - This section relies on section 6.1 of rfc 9301 and gives as an
example the simplest use case. The concluding paragraph also gives the
impression that this is the only processing pub sub needs to do. Both the
section 6.1 and here do not address all the use cases.
I suggest removing this from the introduction and instead clearly define
the scope and then define all the use cases as in a real deployment
scenario in section 3. See more about this below.
<...>
3. Deployment Assumptions
The specification described in this document makes the following
deployment assumptions:
(1) A unique 128-bit xTR-ID (plus a 64-bit Site-ID) identifier is
assigned to each xTR.
(2) Map-Servers are configured in proxy-reply mode, i.e., they are
solicited to generate and send Map-Reply messages for the
mappings they are serving.
The distribution of xTR-IDs (and Site-IDs) are out of the scope of
this document.
<...>
PPE - The section 3 is sparse and could define use cases in this section. In
a real life deployment, there may be a variety of use cases such as
1. an ITR/PITR/RTR joins an existing LISP network and subscribes to
specific existing EID prefixes updates (this is addressed in the intro)
2. an ITR/PITR/RTR joins "early" a growing LISP network and subscribes to
an EID prefix NOT YET present in the database ( covered by 8.4 in rfc 9301?
- more below)
3. an ITR/PITR/RTR sends multiple requests where the range of prefix/len is
removed and readded are slightly different or overlapping, how do we
cover the use case of "holes"?
4. scale - what if we have a large number of subscriptions - do we intend
them to be aggregated or rely on 5.5 in rfc 9301?
The document would be much clearer if the processing expected for each of
these use cases were described explicitly.
Consider, the pub sub mechanism is used to minimize the number of messages
exchanged and timing issues by using a triggered event solution. However,
it is unclear how it works for use case 2 when there is no existing EID
entry yet. Upon receiving a negative map reply should there be periodic
resend of SMR from the RTR/ITR/PITR? Or is the first SMR stored somewhere
on the Mapping System on a temporary entry and when the EID is added later
does it trigger the response? If the entry is temporary must the SMR
requestors renew their request- if so what periodicity? Can the two
behaviors coexist?
If there is periodic resend until the EID entry is present then the pub sub
is still polling for an event rather than being event driven for the first
part of the process then the MS and requestors should have a configuration
that accounts for the polling or timing out of an entry.
As different implementations may have specific behaviors (e.g retry when it
receives a negative map reply or assumption a subscription is
preprovisioned) there is an implicit assumption both endpoints are acting
in a cooperative manner. Perhaps there is another deployment
assumption that the mapping system and the RTR/ITR/PITR have a
collaborative behavior (periodicity, polling mechanism, event trigger) by
config or default config.
Thanks
Padma
On Fri, Dec 9, 2022 at 3:48 AM Jordi Paillissé <jordi.pailli...@upc.edu>
wrote:
> +1
>
> Jordi
>
> El 8/12/22 a les 22:18, Prakash Jain (prakjain) ha escrit:
> > +1
> > - Prakash
> >
> > On 12/8/22, 8:09 AM, "lisp on behalf of Sharon Barkai" <
> lisp-boun...@ietf.org on behalf of sharon.barkai=
> 40getnexar....@dmarc.ietf.org> wrote:
> >
> > ++
> >
> > --szb
> > Cell: +972.53.2470068
> > WhatsApp: +1.650.492.0794
> >
> > > On Dec 8, 2022, at 18:02, Dino Farinacci <farina...@gmail.com>
> wrote:
> > >
> > >
> > >>
> > >> Hi Luigi, all,
> > >>
> > >> I also think that it is reasonable to publish this spec as a
> proposed standard.
> > >
> > > +1.
> > >
> > > Dino
> > > _______________________________________________
> > > lisp mailing list
> > > lisp@ietf.org
> > > https://www.ietf.org/mailman/listinfo/lisp
> >
> > _______________________________________________
> > lisp mailing list
> > lisp@ietf.org
> > https://www.ietf.org/mailman/listinfo/lisp
> >
>
> _______________________________________________
> lisp mailing list
> lisp@ietf.org
> https://www.ietf.org/mailman/listinfo/lisp
>
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