Networks ignoring prepends?

Tue Jan 23 20:34:41 UTC 2024

* bill at herrin.us (William Herrin) [Tue 23 Jan 2024, 21:02 CET]:
>On Tue, Jan 23, 2024 at 11:45 AM Owen DeLong via NANOG <nanog at nanog.org> wrote:
>>The catch to all of that, however, is that he’s not directly 
>>peered with 3356 and many AS operators strip communities.
>
>And even if I didn't, the problem isn't just one ISP localprefing to 
>prefer distant routes. Centurylink most directly impacts me, but as 
>others have pointed out: many ISPs do the same darn thing. The only 
>workable solution available to me appears to be tripling my presence 
>in the DFZ tables.

Why do you buy from ISPs when you don't want to receive traffic via 
them?

Have you tried asking that upstream to interconnect more locally with 
certain other networks?

Why do you buy from ISPs that strip TE communities from your 
announcements that don't affect them in the first place?

>Because big operators think it reasonable to localpref distance 
>routes ahead of nearby ones so long as the distant routes arrive 
> from customers. I'll remember that the next time folks complain 
>about the size of the routing table. This one you did to yourselves.

BGP, while a distance vector protocol, famously does not take 
latency into account when making routing decisions.

	-- Niels.