Networks ignoring prepends?

Mon Jan 22 21:11:25 UTC 2024

On Jan 22, 2024, at 14:35, William Herrin <bill at herrin.us> wrote:
> 
> The best path to me from Centurylink is: 3356 1299 20473 11875
> 
> The path Centurylink chose is: 3356 47787 47787 47787 47787 53356
> 11875 11875 11875
> 
> Do you want to tell me again how that's a reasonable path selection,
> or how I'm supposed to pass communities to either 20473 or 53356 which
> tell 3356 to behave itself?

This certainly seems like a reasonable path selection, in the context that 47787 is likely a 3356 customer.

AS53356 (Free Range Cloud Hosting) appears to have some limited BGP communities that may help.

https://docs.freerangecloud.com/en/bgp/communities

implies that you sending 53356:19014 would block announcements to 47787.
That may turn into a game of whack a mole, but the knobs appear to be there to try something other than prepending to influence 3356’s selection.

—
Andrew Hoyos
hoyosa at gmail.com <mailto:hoyosa at gmail.com>

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