On Thu, Aug 12, 2021 at 10:39 AM Amir Herzberg <amir.lists@gmail.com> wrote:
On Thu, Aug 12, 2021 at 1:22 PM William Herrin <bill@herrin.us> wrote:
A originates 10.0.0.0/16 to paid transit C B originates 10.0.1.0/24 also to paid transit C
Bill, I beg to respectfully differ, knowing that I'm just a researcher and working `for real' like you guys, so pls take no offence.
Hi Amir, Why would I take offense? How do any of us learn except by trying to poke holes in claims to see what holds up and what doesn't?
I don't think A would be right to filter these packets to 10.0.1.0/24; A has announced 10.0.0.0/16 so should route to that (entire) prefix, or A is misleading its peers.
The alternative is that A has to disaggregate 10.0.0.0/16 into at least 8 prefixes on the -possibility- that some jackass might filter the one /24 that B announces. If trying to filter one route results in 7 extra routes being added to the table, that's net badness. Filtering may not even be intentional on A's part. If A's peering router only receives A's customer-originated routes (a common enough architecture) then the peering router won't even have a route to B while B's route only arrives from C. Regards, Bill Herrin -- William Herrin bill@herrin.us https://bill.herrin.us/