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

Jon Lewis jlewis at
Mon Oct 10 18:18:04 UTC 2022

You’ll need to be very selective about the IP ranges you apply that filter to, or more likely, just do it and make sure have one or more default routes to devices/providers that carry full tables. 

As for alternate devices, have you looked at Arista 7280, particularly the Jericho >1 versions. 

Sent from my iPhone

> On Oct 10, 2022, at 10:59 AM, Edvinas Kairys < at> 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

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