Robert,
On 24/09/2025 10:47, Robert Raszuk wrote:
Hi,
This text talks about filtering.
I was looking for any text which would indicate that UPA can be a
prefix with any mask.
UPA uses TLVs that are used for prefix advertisememt, which all have
prefix/mask. There is no text in the draft that would limit the mask to
any specific value. That gives you what you ask for.
thanks,
Peter
Thx
R.
On Wed, Sep 24, 2025, 06:44 Ketan Talaulikar <[email protected]>
wrote:
Robert, I didn't see anything in the document that restricts the
UPA to a /32 or a /128. However, you will find the text below in
https://www.ietf.org/archive/id/draft-ietf-lsr-igp-ureach-prefix-announce-09.html#section-2
that may be somewhat related to what you are looking for ?
Implementations MAY limit the UPA generation to specific prefixes,
e.g. host prefixes, SRv6 locators, or similar. Such filtering is
optional and MAY be controlled via configuration.
Thanks,
Ketan
On Wed, Sep 24, 2025 at 4:07 AM Robert Raszuk <[email protected]>
wrote:
All,
Reading the below I have a tiny question -
Can UPA be a (sub)summary route covering in one shot more than
one address which went down ? Or is there any mandate in the
draft that UPA MUST ALWAYS be /32 or /128 only ?
Apologies if I missed an answer to it in the text of the draft.
Thx,
R.
KT> Section 2 has the following text:
Implementations MAY limit the UPA generation to specific
prefixes, e.g. host prefixes, SRv6 locators, or similar.
Such filtering is optional and MAY be controlled via
configuration.
It is also RECOMMENDED that implementations limit the
number of UPA advertisements which can be originated at a
given time.
I assume the reason for this is to ensure that in some
pathological cases, there is not a storm of UPAs or a
large number of UPAs being generated. If we consider
access, aggregation, and core layers, then at each
progressive level the propagation involves the UPAs of the
lower level of hierarchy being sent towards the core. In
this case, the propagating ABR/ASBRs are also kind of
originating from the UPAs from the lower layer in its
LSAs/LSPs. So, shouldn't the same controls/limits apply at
those routers as well? Perhaps consider tweaking the
language in the above text to cover both origination and
propagation? I am not looking for mention of specific knobs.
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