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


From: Andrey Kostin <ankost () podolsk ru>
Date: Fri, 14 Oct 2022 08:47:24 -0400

David Conrad писал(а) 2022-10-12 11:39:
Andrey,

There was a period in the mid- to late-90s where some of RIRs
allocated longer than /24s, i.e., to match the amount of address space
justified by the requester, even if that meant (say) a /29. This
didn’t last very long as one of the (at the time) 800 lb gorillas
(Sprint) decided to start filtering at /19 (which IIRC was the default
prefix length RIPE-NCC chose to allocate to LIRs) to keep their
routers from falling over.

I'm looking at it only from a practical side. I worked for different ISPs in RIPE region in 2000-s and never saw anything like that. There was a requirement from RIPE to create an object for any assigned /29 subnet and larger for IP space usage documentation, but from allocated block. Anyways, even is it's true, it doesn't change anything. There are /24 PI blocks and if /24s are filtered, default route must be in use to have functional Internet connectivity.

Thanks,
Andrey


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