RE: DMARC ViolationAS21299 - 46.42.196.0/24 ASN prepending 255 times

[Adam Thompson <athompson () merlin mb ca>]

Tom, how exactly does someone “ride the 0/0” train in the DFZ?

I’m connected to both commercial internet and NREN, and unfortunately-long paths are not uncommon in this scenario, in 
order to do traffic steering.  If there’s another solution that affects global inbound traffic distributions, I’d love 
to hear about it (and so would a lot of my peers in edu).

If there were a usable way to “dump” the excessively-long path only as long as a better path was already known by at 
least one edge router, that might be workable, but you’d have to keep track of it somewhere to reinstall it if the 
primary route went away… at which point you may as well have not dropped it in the first place.

-Adam

Adam Thompson
Consultant, Infrastructure Services
[MERLIN]
100 - 135 Innovation Drive
Winnipeg, MB, R3T 6A8
(204) 977-6824 or 1-800-430-6404 (MB only)
athompson () merlin mb ca<mailto:athompson () merlin mb ca>
www.merlin.mb.ca<http://www.merlin.mb.ca/>

From: NANOG <nanog-bounces+athompson=merlin.mb.ca () nanog org> On Behalf Of Tom Beecher
Sent: Friday, March 25, 2022 4:13 PM
To: Paschal Masha <paschal.masha () ke wananchi com>
Cc: nanog <nanog () nanog org>
Subject: Re: DMARC ViolationAS21299 - 46.42.196.0/24 ASN prepending 255 times

The best practice with regards to as_path length is to have an edge filter that dumps any prefix with a length longer 
than say 10. Depending on the situation, might even be able to go smaller.

At a certain point, keeping that route around does nothing for you, just shoot it and ride the 0/0 train.

On Fri, Mar 25, 2022 at 4:09 AM Paschal Masha <paschal.masha () ke wananchi com<mailto:paschal.masha () ke wananchi 
com>> wrote:
:) probably the longest prepend in the world.

A thought though, is it breaking any standard or best practice procedures?

Regards
Paschal Masha | Engineering
Skype ID: paschal.masha

----- Original Message -----
From: "Erik Sundberg" <ESundberg () nitelusa com<mailto:ESundberg () nitelusa com>>
To: "nanog" <nanog () nanog org<mailto:nanog () nanog org>>
Sent: Friday, March 25, 2022 6:43:38 AM
Subject: DMARC ViolationAS21299 - 46.42.196.0/24<http://46.42.196.0/24> ASN prepending 255 times

If anyone from AS21299 is lurking on Nanog. Please reduce your AS prepends for 46.42.196.0/24<http://46.42.196.0/24> 
from 255 prepends to a more reasonable number of prepends let's say 20. Thanks!

This is a Kazakhstan register IP Block and ASN



Network Next Hop Metric LocPrf Weight Path

*> 46.42.196.0/24<http://46.42.196.0/24> x.x.x.x 0 100 0 2914 174 3216 3216 35168 21299 21299 21299 21299 21299 21299 
21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 
21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 
21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 
21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 
21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 
21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 
21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 
21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 
21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 
21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 
21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 
21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 21 299 21299 21299 21299 
21299 21299 21299 21299 21299 21299 21299 21299 21299 21299 i








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