Hi Les,
Thanks for your comments.
This is an informational document which describes the applicability of existing
IS-IS MT mechanisms for building SR based NRPs. All the normative references
are either RFCs or stable WG documents. It is true that some informative
references are individual documents, while they just provide additional
information related to this topic, thus would not impact the stability and
maturity of the proposed mechanism.
The text you quoted from draft-ietf-teas-nrp-scalability are about the
considerations when the number of NRP increases, how to minimize the impact to
the routing protocols (e.g. IGP). While as described in the scalability
considerations section of this document, the benefit and limitation of using
this mechanism for NRP are analyzed, and it also sets the target scenarios of
this mechanism:
“The mechanism described in this document is considered useful for network
scenarios in which the required number of NRP is small”
Thus it is clear that this solution is not recommended for network scenarios
where the number of required NRP is large.
Please note section 3 of draft-ietf-teas-nrp-scalability also mentioned that:
“The result of this is that different operators can choose to deploy
things at different scales.”
And
“In particular, we should be open to the use of approaches that do not
require control plane extensions and that can be applied to deployments with
limited scope.”
According to the above text, we believe the mechanism described in this
document complies to the design principles discussed in
draft-ietf-teas-nrp-scalability and provides a valid solution for building NRPs
in a limited scope.
Hope this solves your concerns about the maturity and scalability of this
mechanism.
Best regards,
Chongfeng
From: Les Ginsberg \(ginsberg\)
Date: 2024-01-11 08:21
To: Joel Halpern; Acee Lindem; [email protected]; [email protected]
Subject: Re: [Lsr] [Teas] Fwd: Working Group Last Call for "Applicability of
IS-IS Multi-Topology (MT) for Segment Routing based Network Resource Partition
(NRP)" - draft-ietf-lsr-isis-sr-vtn-mt-06
(NOTE: I am replying to Joel’s post rather than the original last call email
because I share some of Joel’s concerns – though my opinion on the merits of
the draft is very different.
Also, I want to be sure the TEAS WG gets to see this email.)
I oppose Last Call for draft-ietf-lsr-isis-sr-vtn-mt.
It is certainly true, as Joel points out, that this draft references many
drafts which are not yet RFCs – and in some cases are not even WG documents.
Therefore, it is definitely premature to last call this draft.
I also want to point out that the direction TEAS WG has moved to recommends
that routing protocols NOT be used as a means of supporting NRP.
https://www.ietf.org/archive/id/draft-ietf-teas-nrp-scalability-03.html#name-scalabliity-design-principl
states:
“…it is desirable for NRPs to have no more than small impact (zero being
preferred) on the IGP information that is propagated today, and to not required
additional SPF computations beyond those that are already required.”
https://www.ietf.org/archive/id/draft-ietf-teas-nrp-scalability-03.html#name-scalabliity-design-principl
states:
“The routing protocols (IGP or BGP) do not need to be involved in any of these
points, and it is important to isolate them from these aspects in order that
there is no impact on scaling or stability.”
Another draft which is referenced is
https://datatracker.ietf.org/doc/draft-dong-lsr-sr-enhanced-vpn/ - which is not
a WG document and – based on the recommendations in
draft-ietf-teas-nrp-scalability – I would argue that the IGPs should NOT be
extended as proposed in this draft. So if a WG adoption call were to initiated
for draft-dong-lsr-sr-enhanced-vpn, I would oppose it.
This then puts draft-ietf-lsr-isis-sr-vtn-mt in the position of publishing
information about a solution which the IETF is discouraging. I do not know why
the IETF would want to do this.
If, despite all of the above, at some point it is judged not premature to
publish this draft, I think the draft should at least include statements
indicating that this approach is not a recommended deployment solution.
Les
From: Lsr <[email protected]> On Behalf Of Joel Halpern
Sent: Wednesday, January 10, 2024 3:22 PM
To: Acee Lindem <[email protected]>; [email protected]; [email protected]
Subject: Re: [Lsr] [Teas] Fwd: Working Group Last Call for "Applicability of
IS-IS Multi-Topology (MT) for Segment Routing based Network Resource Partition
(NRP)" - draft-ietf-lsr-isis-sr-vtn-mt-06
Given that the documents that provide the basic definitions needed for this are
still active Internet Drafts, it seems premature to last call this document.
As a lesser matter, it seems odd that draft-ietf-teas-ietf-network-slices,
which defines the terms needed to understand this draft, is an Informative
reference.
Yours,
Joel
PS: I considered not writing this email, as it seems quite reasonable to use MT
to support what I expect NRPs to be. So in principle I think the document is a
good idea.
On 1/10/2024 6:12 PM, Acee Lindem wrote:
Note that we are last calling this informational document relating to IS-IS
deployment of NRPs using multi-topology. If you have comments, please send them
to the LSR list.
Thanks,
Acee
Begin forwarded message:
From: Acee Lindem <[email protected]>
Subject: Working Group Last Call for "Applicability of IS-IS Multi-Topology
(MT) for Segment Routing based Network Resource Partition (NRP)" -
draft-ietf-lsr-isis-sr-vtn-mt-06
Date: January 8, 2024 at 5:50:21 PM EST
To: Lsr <[email protected]>
This begins a two week LSR Working Group last call for the “Applicability of
IS-IS Multi-Topology (MT) for Segment Routing based Network Resource Partition
(NRP)”. Please express your support or objection prior to Tuesday, January
23rd, 2024.
Thanks,
Acee
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