nanog mailing list archives

Re: maximum ipv4 bgp prefix length of /24 ?


From: Crist Clark <cjc+nanog () pumpky net>
Date: Wed, 4 Oct 2023 22:49:09 -0700

Been resisting adding to this thread...

But if the assumption is that networks will always eventually totally
deaggregate to the maximum, we're screwed. Routing IPv4 /32s would be
nothing. The current practice of accepting /48s could swell to about 2^(48
- 3) = 2^45 = 35184372088832.

What will prevent unrestricted growth of the IPv6 table if operators push
everything out to /48 "to counter hijacks" or other misguided reasons?

On Wed, Oct 4, 2023 at 8:14 AM Owen DeLong via NANOG <nanog () nanog org>
wrote:

If you maximally disaggregate to /24, you end up with about 12M fib
entries. At /25 this doubles and you double it again for every bit you move
right.

At /24, we are on borrowed time without walking right. Also, the CPU in
most routers won’t handle the churn of a 10M prefix RIB.

Owen


On Oct 4, 2023, at 03:15, Mark Tinka <mark@tinka.africa> wrote:



On 10/4/23 12:11, Musa Stephen Honlue wrote:

Which one is easier,

1. Convincing the tens of thousands of network operators and equipment
vendors to modify configs and code to accept more specifics than /24, or

Equipment vendors can already support 10 million entries in FIB. They
just ask for a little bit of cash for it.

Mark.




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