Robert,
On 23/04/2025 00:44, Robert Raszuk wrote:
All,
I have one more question in respect to the text in the draft ...
*/4. Generation of the UPA
UPA MAY be generated by the ABR or ASBR that is performing the
summarization, when all of the following conditions are met:
- reachability of a prefix that was reachable earlier was lost
- a summary address which covers the prefix is being advertised by
the ABR/ASBR/*
So with the above text in mind would we advertise UPA when:
A) Operator manually sets overload bit on an egress PE ? (Technically
the node is still reachable)
B) Operator manually forces to advertise within L1 max metric for its
router-LSA ? (Technically the node is still reachable)
In both cases the second condition is met - summary covers the egress
node of the sare L1 or non 0 area.
My reading of section 4 leads me to believe that the answer to both
(A) and (B) questions is "no" - and that would be perhaps something
worth revisiting.
yes, UPA would be advertised. The point is that you want the ingress PE
to reroute if there is an alternative egress PE that can reach BGP
prefix located behind the PE where (A) or (B) was done.
thanks,
Peter
Thx,
Robert
On Tue, Apr 22, 2025 at 11:29 PM Robert Raszuk <rob...@raszuk.net> wrote:
Hi Les,
Let's open a bit of imagination and assume one day we progress
https://datatracker.ietf.org/doc/html/draft-ietf-lsr-isis-extended-hierarchy-06
Do you think this is wise to blast UPAs everywhere in all 8 levels
when perhaps it is needed only on a few egress nodes sitting in
one specific area of say level 4 ?
I do understand your statement that since we are creating
summaries we are the problem and need to fix it but let's not
forget that summaries are created by operators and such operators
can use other tools to signal holes in them. Both droid and bgp
based models have been discussed yet UPA is being pushed.
It seems that UPAs are example of very good marketing skills :).
Cheers,
Robert
On Tue, Apr 22, 2025 at 4:35 PM Les Ginsberg (ginsberg)
<ginsberg=40cisco....@dmarc.ietf.org> wrote:
I support progression of the UPA draft.
It leverages an existing mechanism in the protocols to provide
needed functionality - which has been proven viable by
multiple implementations.
As I have commented in the past, I do wish the definition of
the flags was modified so they were not mutually exclusive.
This model leads to the inability to add additional related
flags in the future without creating a backwards compatibility
issue.
Regarding concerns expressed by other WG members as to the
appropriateness and scalability of the mechanism defined here:
I think the draft is careful in defining how the mechanism
should be used so
as to avoid scalability issues. I also think no one has
offered an alternative which is more scalable.
Given IGPs already advertise reachability, summaries, and
unreachability, this mechanism is clearly an appropriate use
of the IGPs.
Les
*From:*Yingzhen Qu <yingzhen.i...@gmail.com>
*Sent:* Thursday, April 17, 2025 11:13 AM
*To:* lsr <lsr@ietf.org>; lsr-chairs <lsr-cha...@ietf.org>
*Subject:* [Lsr] WG Last Call for
draft-ietf-lsr-igp-ureach-prefix-announce (4/17/2025 - 5/2/2025)
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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