Hi Padma,
Thanks a lot for your feedback! Let me spin out a new thread to better address
your comments.
We were about to submit version -10 of the document addressing (hopefully) all
the feedback received so far (which has been significant). If it is fine with
you, I’ll still proceed with submitting version -10 (today or tomorrow, likely)
in its current form. Then we can discuss your latest feedback here and any
potential changes coming from the discussion can go into -11, sounds good?
Also, given that there seems to be support for moving the document to Standards
Track, I’ll submit version -10 as Standards already, hoping this is fine.
Regarding your feedback below, I think you’re making some good questions. Let
me put together some text to address your comments. I’ll get back to you
shortly.
Thanks!
Alberto
From: lisp <lisp-boun...@ietf.org> on behalf of Padma Pillay-Esnault
<padma.i...@gmail.com>
Date: Thursday, January 5, 2023 at 8:29 AM
To: Alberto Rodriguez-Natal (natal) <natal=40cisco....@dmarc.ietf.org>
Cc: lisp@ietf.org <lisp@ietf.org>, Sharon Barkai
<sharon.barkai=40getnexar....@dmarc.ietf.org>, Jordi Paillissé
<jordi.pailli...@upc.edu>
Subject: Re: [lisp] LISP PubSub to Proposed Standard?
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
[Image removed by sender.]
On Fri, Dec 9, 2022 at 3:48 AM Jordi Paillissé
<jordi.pailli...@upc.edu<mailto: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<mailto:lisp-boun...@ietf.org> on behalf of
> sharon.barkai=40getnexar....@dmarc.ietf.org<mailto: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<mailto: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<mailto:lisp@ietf.org>
> > https://www.ietf.org/mailman/listinfo/lisp
>
> _______________________________________________
> lisp mailing list
> lisp@ietf.org<mailto:lisp@ietf.org>
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>
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