nanog mailing list archives

Re: Route optimization using GPUs?


From: Tom Beecher <beecher () beecher cc>
Date: Fri, 6 Dec 2024 16:45:50 -0500

Ryan-

Unfortunately it doesn't appear that you have a solid understanding of core
BGP fundamentals.

I suggest starting with a read of RFC4271.

Have a great weekend and holiday season.


On Fri, Dec 6, 2024 at 1:19 PM Ryan Hamel <ryan () rkhtech org> wrote:

Tom,

The automotive industry has normalized "synthetic". It's motor oil that is
artificially created, vs pulled out of the ground and refined. It's a
perfect analogy for routes that were created by third-party software, vs
organically created/redistributed from the proper AS.

Ryan Hamel


------------------------------
*From:* Tom Beecher <beecher () beecher cc>
*Sent:* Friday, December 6, 2024 10:10 AM
*To:* Ryan Hamel <ryan () rkhtech org>
*Cc:* Nick Hilliard <nick () foobar org>; nanog () nanog org <nanog () nanog org>
*Subject:* Re: Route optimization using GPUs?

Caution: This is an external email and may be malicious. Please take care
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not properly prepending communities on synthetic routes


Let's not normalize 'synthetic route' as a term. It's not a thing that
exists.


On Fri, Dec 6, 2024 at 12:32 PM Ryan Hamel <ryan () rkhtech org> wrote:

Nick,

I understand there are rules and unspoken guidelines/rules for the DFZ,
but when it comes to each individual AS, that org/operator can run their AS
internally however they please, and maybe they have considered the risks
you have mentioned.

That said, I can argue that upstreams not filtering their customers
properly removes a safety guard, upstreams not implementing RPKI removes a
safety guard, not properly prepending communities on synthetic routes to
drop them on export again removes a safety guard. I can go on...

   - As an industry, we should be well beyond the point of having to tell
   people that this is a poor idea, in the same way that we don't need to tell
   people that bypassing electrical fuse boxes is a poor idea, or removing
   railings on stair-cases, or not wearing motorbike helmets, or anything else
   designed to mitigate the unfortunate consequences of entirely predictable
   accidents.

Where this statement falls short is, those are all regulated by building
codes, laws, etc. No laws exist dictating how BGP, routing protocols in
general, and topologies must be implemented, nor what safety guidelines
must be adhered to.

Ryan Hamel


------------------------------
*From:* Nick Hilliard <nick () foobar org>
*Sent:* Friday, December 6, 2024 8:34 AM
*To:* Ryan Hamel <ryan () rkhtech org>
*Cc:* Tom Beecher <beecher () beecher cc>; nanog () nanog org <nanog () nanog org>
*Subject:* Re: Route optimization using GPUs?

Caution: This is an external email and may be malicious. Please take care
when clicking links or opening attachments.


Ryan Hamel wrote on 05/12/2024 23:45:
What does "these devices don't follow standard BGP behaviors" have to do
with adding a NO_EXPORT or specific community on the import policy when
a route is accepted, and being belt & suspenders with matching those
communities to drop those routes on export to carriers/IX/PNI sessions?

Ryan,

BGP ensures loop-free interdomain path computation by inspecting the AS
path of each NLRI.  If a routing optimiser rewrites all the AS paths for
all the NLRIs it receives, then it's just pooped all over the primary
component of BGP that's designed to ensure that interdomain BGP actually
works in the way that it's supposed to do in the first place, which also
acts as an intrinsic safety guard against dfz hijacking.

Removing an intrinsic safety guard like this is an inherently risky
thing to do. When you elevate the inherent risk of a system, you
necessarily elevate either the likelihood of failure or the consequences
of a failure, or both.

As an industry, we should be well beyond the point of having to tell
people that this is a poor idea, in the same way that we don't need to
tell people that bypassing electrical fuse boxes is a poor idea, or
removing railings on stair-cases, or not wearing motorbike helmets, or
anything else designed to mitigate the unfortunate consequences of
entirely predictable accidents.

Nick



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