On 23/04/2025 11:18, Aijun Wang wrote:
Hi, All:
I read carefully again the WGLC draft, and OBJECT strongly for its
forwarding.
The reasons are the followings:
_Section I: Decent IETF Behaviors_
1)The scenario, initial solution and intense discussions are
described, initiated, organized by the authors of
https://datatracker.ietf.org/doc/html/draft-wang-lsr-prefix-unreachable-annoucement-00
(From October 2019), there is no any mentions in this document for
these experts’ efforts. This is not the decent behavior within IETF.
2)The idea of
https://datatracker.ietf.org/doc/html/draft-ietf-lsr-igp-ureach-prefix-announce-04#section-4
is first describe in
https://datatracker.ietf.org/doc/html/draft-wang-lsr-prefix-unreachable-annoucement-06#section-7
(March, 2021), ONE YEAR Earlier than the initial draft of the WGLC
document.(https://datatracker.ietf.org/doc/html/draft-ppsenak-lsr-igp-ureach-prefix-announce-00)
(March, 2022). This is another non-decent behavior within IETF.
_Section II: Technical Analysis_
you keep repeating the same arguments over and over. These have been
responded to numerous times during the adoption call and during the
existence of the draft as a WG document.
I'm going to put my responses below just to satisfy the IETF process,
but I'm NOT going to continue the discussion any further.
__
1)The WGLC provide two methods to label the unreachable prefixes, one
depends on LSInifinity setting of the advertised prefix, the other
depends on the newly defined flag.
They are redundancy and confusion. The meaning of LSinifinity is
already defined in the existing documents, and there is no necessary
to rephrase them. The solution needs only depend on one method.
the newly define flag is not to signal unreachability, it is rather to
signal a reason for it.
2)For the usage of LSInifinity, although RFC 2328 and RFC 5305 defines
its possible usage, if they are used in such way(I have not heard any
operator deploy such mechanics), their deployment should be gradually
disappearing, not enhance instead. There are three reasons for such
considerations:
a)The maximum metric value is often treated as the last resort of
reachability, not the unreachability. It will lead more confusions
for the setting of such metric in the network.
b)It states clearly in the RFC 2328 section 14.1, that “Premature
aging can also be used when, for example, one of the router's
previously advertised external routes is no longer reachable. In this
circumstance, the router can flush its AS- external-LSA from the
routing domain via premature aging. This procedure is _preferable to_
the alternative, which is to originate a new LSA for the destination
_specifying a metric of LSInfinity_."
c)During the SPF calculation, the final cost is the summary of every
segment cost. It is possible that the final cost exceed also the
LSinfinity, but the prefix is reachable.
LSInifinity is something that has been defined in a base protocol
specification and is part of the protocol. It's meaning is clearly
defined and it's usage is allowed whether you like it or not.
3)For the Signaling Method, it defines the additional flags based one
newly defined sub-TLV for OSPF, and existing sub-TLV for IS-IS.
Far complex than the usage of “Prefix Originator” directly. The
document just want to make some differences, not the efficiency.
Using “Prefix Originator" for signalling unreachability is a completely
broken idea and we have pointed that to you many times. You refused to
accept it, I can't help you with that.
4)The WGLC document doesn’t solve the area/domain partition scenaro,
which may appear in the network, and is already covered by
https://datatracker.ietf.org/doc/draft-wang-lsr-prefix-unreachable-annoucement/
(let’s call it Founder Document). It states, “UPA does not make the
problem of an area partition any worse. ”-----Actually, it does
worse----If one ABR can’t reach the egress router(PE1), but another
ABR can reach, there should be no switchover of the egress
router(PE2), which may be reachable, or may be unreachable.-----There
should be some coordinate mechanism among the ABRs, as that described
in the above Founder Document.
as I mentioned several times before, UPA is not trying to address the
area partition.
You are free to write a new draft that solves it, but please keep it
orthogonal to UPA.
5)There is no any consideration for the balance of reachable
information and unreachable information announcements. It will be
disaster in some critical condition.
I think the draft is careful in defining how the mechanism should be
used so as to avoid scalability issues.
Regards,
Peter
Best Regards
Aijun Wang
China Telecom
*发件人:*[email protected]
[mailto:[email protected]] *代表 *Aijun Wang
*发送时间:*2025年4月22日0:12
*收件人:*Yingzhen Qu <[email protected]>
*抄送:*lsr <[email protected]>; lsr-chairs <[email protected]>
*主题:*[Lsr] Re: WG Last Call for
draft-ietf-lsr-igp-ureach-prefix-announce (4/17/2025 - 5/2/2025)
I object its forwarding, from the beginning of its WG adoption.
Aijun Wang
China Telecom
On Apr 18, 2025, at 02:13, Yingzhen Qu <[email protected]>
wrote:
Hi,
This email begins a 2 week WG Last Call for the following draft:
IGP Unreachable Prefix Announcement
https://datatracker.ietf.org/doc/draft-ietf-lsr-igp-ureach-prefix-announce/
Please review the document and indicate your support or objections
by May 2nd, 2025.
Authors and contributors,
Please indicate to the list your knowledge of any IPR related to
this work.
Thanks,
Yingzhen
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