Hi Acee:
In the scenario mentioned by Robert, the section 6.1 solution doesn't work.
When BGP needs to detect the reachability of the next hop to trigger BGP
convergence.
Thanks
Zhibo Hu
-----Original Message-----
From: Acee Lindem (acee) [mailto:a...@cisco.com]
Sent: Tuesday, July 28, 2020 9:24 PM
To: Huzhibo <huzh...@huawei.com>; Aijun Wang <wang...@chinatelecom.cn>;
lsr@ietf.org
Cc: Xiaoyaqun <xiaoya...@huawei.com>
Subject: Re: [Lsr] New Version Notification for
draft-wang-lsr-prefix-unreachable-annoucement-03.txt
See my response to Aijun... Please provide topologies where the section 6.1
solution doesn't work.
Acee
On 7/27/20, 10:03 PM, "Huzhibo" <huzh...@huawei.com> wrote:
Hi Acee:
In fact, we have meet some scenarios where redundant paths cannot be
deployed within a area. Especially when the access area uses the nearby access
principle, ABRs form disordered combinations, which makes it difficult to
deploy physical or tunnel connections. In addition, advertising unreachable
prefixes can prevent traffic detours. Of course, This draft also has some other
attempts to use Segment Routing to automatically establish connections between
ABRs.
Thanks
Zhibo Hu
-----Original Message-----
From: Acee Lindem (acee) [mailto:a...@cisco.com]
Sent: Tuesday, July 28, 2020 1:51 AM
To: Aijun Wang <wang...@chinatelecom.cn>; lsr@ietf.org
Cc: Huzhibo <huzh...@huawei.com>; Xiaoyaqun <xiaoya...@huawei.com>
Subject: Re: [Lsr] New Version Notification for
draft-wang-lsr-prefix-unreachable-annoucement-03.txt
Speaking as an LSR Working Group member:
Asking the WG precisely how to advertise prefix unreachability is the wrong
question - it is analogous to asking whether to use a car or truck to drive off
the edge of a cliff. Rather than messing up OSPF and IS-IS with these complex
and unnecessary mechanisms, it would be better to address the requirement in
your network design. Note that the unreachability of a given summarized prefix
is only relevant if it is reachable through another ABR. In this case, the
network design should provide adequate intra-area redundancy to provide
communications between the ABRs. If this cannot be accomplished, an intra-area
adjacency should be established over a tunnel between the ABRs in the backbone.
Contrary to section 6.1, Looping is normally not a problem as ABRs should add
back hole routes for their advertised summaries.
Acee
On 7/26/20, 9:34 PM, "Lsr on behalf of Aijun Wang" <lsr-boun...@ietf.org on
behalf of wang...@chinatelecom.cn> wrote:
Hi, LSR experts:
We have uploaded the new version of this PUA(Prefix Unreachable
Announcement) draft. The main updates are the followings:
1) Describes the solution that using tunnel to redirect traffic among
ABRs, when all ABRs reaches the PUA limit.
2) Describe fast rerouting to avoid routing black hole.
3) Defining PUA capabilities announcements for OSPFv2/OSPFv3 and ISIS.
There are also some arguments about the current solution for PUA, for
example:
1) Is it suitable to set the "Prefix Originator" sub-TLV to NULL to
indicate the prefix is unreachable?
2) if not, what's the consideration? What's the other convincible
solution?
Wish to hear comments and suggestions on the above issues. We will also
have the presentation on the coming IETF LSR meeting.
Best Regards
Aijun Wang
China Telecom
-----Original Message-----
From: internet-dra...@ietf.org [mailto:internet-dra...@ietf.org]
Sent: Monday, July 27, 2020 9:16 AM
To: Zhibo Hu <huzh...@huawei.com>; Aijun Wang
<wang...@chinatelecom.cn>; Yaqun Xiao <xiaoya...@huawei.com>
Subject: New Version Notification for
draft-wang-lsr-prefix-unreachable-annoucement-03.txt
A new version of I-D,
draft-wang-lsr-prefix-unreachable-annoucement-03.txt
has been successfully submitted by Aijun Wang and posted to the IETF
repository.
Name: draft-wang-lsr-prefix-unreachable-annoucement
Revision: 03
Title: Prefix Unreachable Announcement
Document date: 2020-07-27
Group: Individual Submission
Pages: 11
URL:
https://www.ietf.org/internet-drafts/draft-wang-lsr-prefix-unreachable-annoucement-03.txt
Status:
https://datatracker.ietf.org/doc/draft-wang-lsr-prefix-unreachable-annoucement/
Htmlized:
https://tools.ietf.org/html/draft-wang-lsr-prefix-unreachable-annoucement-03
Htmlized:
https://datatracker.ietf.org/doc/html/draft-wang-lsr-prefix-unreachable-annoucement
Diff:
https://www.ietf.org/rfcdiff?url2=draft-wang-lsr-prefix-unreachable-annoucement-03
Abstract:
This document describes the mechanism that can be used to announce
the unreachable prefixes for service fast convergence.
Please note that it may take a couple of minutes from the time of
submission until the htmlized version and diff are available at tools.ietf.org.
The IETF Secretariat
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