Hi all,

Just went through the many emails on local-pref. Thank you all for the 
discussion. Sorry it takes me so long to get to this. I intend to submit an 
update next week before the deadline. I see a couple options. 1) We can 
emphasize that the use of local-pref to locally override AS path selection 
should be avoided as David Farmer suggested. Or 2) we can remove all discussion 
of local-pref as Randy and Alegandro suggested. We will do whatever the wg 
recommends.

Thanks,
mike

 
-----Original Message-----
From: Alejandro Acosta <[email protected]> 
Sent: Wednesday, August 6, 2025 6:35 AM
To: [email protected]
Subject: [GROW] Re: I-D Action: draft-ietf-grow-as-path-prepending-16.txt

Hello,


On 5/8/25 5:06 PM, Randy Bush wrote:
>>> Move the use of Local-Prefrence to the last bullet of Section 4, 
>>> "Best Practice," and rewrite as follows
>>>
>>>     - If possible, the use of local-preference to locally override AS path
>>>     selection should be avoided. This can lead other networks to excessively
>>>     prepend their AS Paths to you in a futile attempt to influence your
>>>     network. Nevertheless, sometimes the use of local-preference is the only
>>>     way to achieve a desired traffic engineer policy.
>>>
>>> Does this strike the right balance for folks?
>> Sort of.  I would twist it a bit differently, something with more 
>> bias on "it's the largest hammer in your toolbox, so use with care" - 
>> can't find good wording right now.
> local pref may be the largest hammer in one's toolbox, but it deals 
> with a very different nail than path prepending.  it influences only 
> inbound routes, i.e. where you send packets.  this is the inverse of 
> as path prepending, which influences from where you receive packets.
>
> the largest hammer in the inbound packet toolbox is deaggregation.  as 
> with all hammers, skill and a bit of wisdom is advised.
>
> i am not sure local pref belongs in this document at all, as its title 
> is path prepending, not general traffic engineering.  but maybe 
> mission creep and corner cases are the foundation of the game.

I have to say that I agree with Randy's comment, the draft is about 
as-path-prepending.

In the document, I would say that there are numerous techniques for traffic 
engineering, and each of them has its pros and cons.


Alejandro,


>
> randy
>
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