Have you ever looked at soBGP or Path State Vectors. Happy to hang out
and explain if it would be helpful, but these are/were effectively BGP
security efforts that were ultimately driving to a DAG overlay.
They failed because the community became extremely focused on securing
"BGP operation" rather than securing the base topology information.
:-) /r
------ Original Message ------
From "Saku Ytti via NANOG" <[email protected]>
To [email protected]
Cc "North American Network Operators Group" <[email protected]>;
"Saku Ytti" <[email protected]>
Date 8/25/2025 02:04:15
Subject Re: Link-state EGP
On Mon, 25 Aug 2025 at 03:44, <[email protected]> wrote:
It has to be a shortest path or at least you have to know their shortest path
doesn't go back through you. Perhaps AS21's shortest path to AS23 is through
you. In a link-state protocol you can't do shit to stop them using you as
transit, besides outright blocking their traffic (breaking the internet) or
splitting your AS in 3.
How many times do I have to say it, maybe with big enough letters? ***A LINK
STATE ROUTING PROTOCOL IS A DISTRIBUTED CONSENSUS ALGORITHM. ALL NODES MUST RUN
THE IDENTICAL ALGORITHM ON IDENTICAL INPUT DATA OR THE NETWORK BREAKS.***
Perhaps you've invented a new type of algorithm where that's not the case. In this case
I suggest ceasing to call it "link state", and writing a detailed paper about
it instead of vague hints.
Oh I'm definitely not writing a paper. But I'm not sure a novel
algorithm is needed (nor am I sure it is not needed). Certainly the
graph cannot be a symmetric directed graph. That is the directions or
arrows represent direction. You have edges which are reachable through
you (customers) and you have edges which can be used to reach your
customers (upstreams).
So my link-state would have AS2[123] edges as reachable through me and
AS3[123] as edges that can be used to reach those AS2[123] edges. So
arbitrary node further down the network wouldn't use me to reach
AS2[123] because of the direction of the arrow.
Only in a link-state protocol! Luckily, BGP is not a link-state protocol.
Of course it is easy to end up with loopy BGP configurations. But then
we change the configuration and come up with something else.
--
++ytti
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