Consistent routing policy?

Tue Sep 17 11:41:57 UTC 2019

On 16/Sep/19 20:26, Töma Gavrichenkov wrote:

>
>
> Not always.

No, longest match ALWAYS wins.

>
> E.g. imagine an ISP who has two connections to the outside world: one
> through a major ISP and the other through an IX.
>
> Such an ISP would be quite inclined both financially and technically
> to import routes just from the IX and set the default to the upstream
> ISP link.  Therefore, an advertisement from the IX would always win no
> matter the length.

Which is why I included, in my previous message:

    So, for example, if the upstream to whom you are sending the /21 doesn't
    do anything about how they learn the /22 from another source, (for their
    network)...

Mark.