Re: [Idr] I-D Action: draft-ietf-idr-rtc-hierarchical-rr-04.txt

[Robert Raszuk <[e-mail]>]

Hi Alex,

I am not actually aware of implementations supporting best external on IBGP
per this paragraph:

*Quote
from https://datatracker.ietf.org/doc/html/draft-ietf-idr-best-external
<https://datatracker.ietf.org/doc/html/draft-ietf-idr-best-external>*


*When selecting the path to add to the Adj-RIB-OUT, this document specifies
that the path that originate from the same mesh MAY be excluded from
consideration.  This results in an Adj-RIB-OUT selection per mesh (the set
of non-client peers or a specific cluster).*

But you are right that this will/would address the issue. In fact our draft
is pretty much proposing the very same as the second option:

*Quote
from https://datatracker.ietf.org/doc/html/draft-ietf-idr-rtc-hierarchical-rr
<https://datatracker.ietf.org/doc/html/draft-ietf-idr-rtc-hierarchical-rr>*

*When advertising an RT membership NLRI to a route-reflector peer (either
client or non-client), if the best path as selected by the path selection
procedure described in Section 9.1 of [RFC4271] is the path received from
this peer, and there are alternative paths received from other peers, then
the most disjoint alternative route SHOULD be advertised to this peer. The
most disjoint alternative path is the path whose CLUSTER_LIST and
ORIGINATOR_ID attributes are diverse from the attributes of the best path.*

Except we specify this further and include not only different mesh criteria
but also ORIGINATOR_ID difference when selecting a different path.

Many thx,
Robert


On Tue, Mar 5, 2024 at 11:09 AM Alexander Okonnikov <
[e-mail]> wrote:

> Hi Robert,
>
> Yes, initially 'best external' addressed eBGP, but later it was
> generalized for RR clusters as well.
>
> BR
> Alexander Okonnikov
>
> 5 марта 2024 г., в 12:53, Robert Raszuk <[e-mail]> написал(а):
>
> Alex,
>
> The draft applies to reflected IBGP routes.
>
> Best external draft you are quoting - which is extremely useful and
> deployed proposal - is applicable to ASBRs/PEs learning BGP routes over
> EBGP.
>
> Thx,
> R.
>
>
>
> On Tue, Mar 5, 2024 at 10:45 AM Alexander Okonnikov <
> [e-mail]> wrote:
>
>> Hi authors,
>>
>> We have already more generic alternative for the second solution - 'Best
>> external route' described in
>> https://datatracker.ietf.org/doc/html/draft-ietf-idr-best-external-05.
>> What about choosing one of two solutions - I lean towards 'best external'
>> based solution. It seems lightweight and doesn't require Add-paths support.
>>
>> Thanks.
>>
>> BR
>> Alexander Okonnikov
>>
>> 4 марта 2024 г., в 13:27, [e-mail] написал(а):
>>
>> Internet-Draft draft-ietf-idr-rtc-hierarchical-rr-04.txt is now
>> available. It
>> is a work item of the Inter-Domain Routing (IDR) WG of the IETF.
>>
>>   Title:   Extensions to RT-Constrain in Hierarchical Route Reflection
>> Scenarios
>>   Authors: Jie Dong
>>            Mach(Guoyi) Chen
>>            Robert Raszuk
>>   Name:    draft-ietf-idr-rtc-hierarchical-rr-04.txt
>>   Pages:   6
>>   Dates:   2024-03-04
>>
>> Abstract:
>>
>>   The Route Target (RT) Constrain mechanism specified in RFC 4684 is
>>   used to build a route distribution graph in order to restrict the
>>   propagation of Virtual Private Network (VPN) routes.  In network
>>   scenarios where hierarchical route reflection (RR) is used, the
>>   existing RT-Constrain mechanism cannot guarantee a correct route
>>   distribution graph.  This document describes the problem scenario and
>>   proposes a solution to address the RT-Constrain issue in hierarchical
>>   RR scenarios.
>>
>> The IETF datatracker status page for this Internet-Draft is:
>> https://datatracker.ietf.org/doc/draft-ietf-idr-rtc-hierarchical-rr/
>>
>> There is also an HTMLized version available at:
>>
>> https://datatracker.ietf.org/doc/html/draft-ietf-idr-rtc-hierarchical-rr-04
>>
>> A diff from the previous version is available at:
>>
>> https://author-tools.ietf.org/iddiff?url2=draft-ietf-idr-rtc-hierarchical-rr-04
>>
>> Internet-Drafts are also available by rsync at:
>> rsync.ietf.org::internet-drafts
>>
>>
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