Re: any dangers of filtering every /24 on full internet table to preserve FIB space ?

[Owen DeLong via NANOG <nanog () nanog org>]

There are most definitely a number of organizations that have /24s that are not part of a larger aggregate.

If you don’t have a default route to some router that takes the full table on your behalf, then you will loose 
connectivity to/from those entities.

Owen


> On Oct 10, 2022, at 07:58 , Edvinas Kairys <edvinas.email () gmail com> wrote:
>
> Hello,
>
> We're considering to buy some Cisco boxes - NCS-55A1-24H. That box has 24x100G, but only 2.2mln route (FIB) memory 
> entries. In a near future it will be not enough - so we're thinking to deny all /24s to save the memory. What do you 
> think about that approach - I know it could provide some misbehavior. But theoretically every filtered /24 could be 
> routed via smaller prefix /23 /22 /21 or etc. But of course it could be a situation when denied /24 will not be 
> covered by any smaller prefix. 
>
> What do you think about this approach ?
>
> Also maybe you know - some advices for edge routers that have at least 8x100G interfaces and "good" memory for prefix 
> count ? Thanks