Networks ignoring prepends?

Mon Jan 22 12:49:47 UTC 2024

Howdy,

Does anyone have suggestions for dealing with networks who ignore my
BGP route prepends?

I have a primary ingress with no prepends and then several distant
backups with multiple prepends of my own AS number. My intention, of
course, is that folks take the short path to me whenever it's
reachable.

A few years ago, Comcast decided it would prefer the 5000 mile,
five-prepend loop to the short 10 mile path. I was able to cure that
with a community telling my ISP along that path to not advertise my
route to Comcast. Today it's Centurylink. Same story; they'd rather
send the packets 5000 miles to the other coast and back than 10 miles
across town. I know they have the correct route because when I
withdraw the distant ones entirely, they see and use it. But this time
it's not just one path; they prefer any other path except the one I
want them to use. And Centurylink is not a peer of those ISPs, so
there doesn't appear to be any community I can use to tell them not to
use the route.

I hate to litter the table with a batch of more-specifics that only
originate from the short, preferred link but I'm at a loss as to what
else to do.

Advice would be most welcome.

Regards,
Bill Herrin

-- 
William Herrin
bill at herrin.us
https://bill.herrin.us/