Re: maximum ipv4 bgp prefix length of /24 ?

["Dale W. Carder" <dwcarder () es net>]

Thus spake Delong.com via NANOG (nanog () nanog org) on Tue, Oct 10, 2023 at 04:52:07PM -0700:
> However, IF YY is paying attention, and YY wants to advertise 2001:db8::/32 as well as allow 2001:db8:8000::/36 and 
> 2001:db8:f000::/36, I would expect AS YY would generate ROAs for
>       2001:db8::/32 with ORIGIN-AS=YY MAXPREFIXLEN=36
>       2001:db8:0::/33 with ORIGIN-AS=0 (no MAXPREFIXLEN needed)
>       2001:db8:8000::/36 with ORIGIN-AS=YY MAXPREFIXLEN=36
>       2001:db8:9000::/35 with ORIGIN-AS=0 (no MAXPREFIXLEN needed)
>       2001:db8:a000::/34 with ORIGIN-AS=0 (no MAXPREFIXLEN needed)
>       2001:db8:c000::/34 with ORIGIN-AS=0 (no MAXPREFIXLEN needed)
>       2001:db8:e000::/36 with ORIGIN-AS=0 (no MAXPREFIXLEN needed)
>       2001:db8:f000::/36 with ORIGIN-AS=YY MAXPREFIXLEN=36

Double check, but offhand I believe in this case you do not need all 
these AS0 ROA's.  Any validated ROA payload fully matching should be
all you need for it to be valid, and anything that is covered by a vrp
but not matching is invalid.

So, I think you can do
        2001:db8::/32 with ORIGIN-AS=YY MAXPREFIXLEN=32
        2001:db8:8000::/36 with ORIGIN-AS=YY MAXPREFIXLEN=36
        2001:db8:f000::/36 with ORIGIN-AS=YY MAXPREFIXLEN=36

Dale