Re: Link-state EGP

[William Herrin via NANOG <nanog () lists nanog org>]

On Sat, Aug 23, 2025 at 7:49 AM Saku Ytti via NANOG
<nanog () lists nanog org> wrote:
> Why do we use distance vector EGP? Why do we advertise prefixes?

Because we like to get paid.

The problem with a link-state protocol is that every link in the
system is a valid transit for every routed prefix. We can control the
link transit costs, prefer some paths over others, but there's no way
to express that even though a particular prefix is attached to a node
on the other side of this link, we're not under any circumstances
permitted to use this link to reach it. As a result, we can only use a
link-state protocol in a system where the subscriber has paid for the
right to use -all- of the links in the system.

Regards,
Bill Herrin


-- 
William Herrin
bill () herrin us
https://bill.herrin.us/
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