Route table growth and hardware to the filter

bmanning at bmanning at
Tue Sep 11 09:15:00 UTC 2007

On Mon, Sep 10, 2007 at 10:16:17AM -0500, Stephen Sprunk wrote:
> Thus spake "Jon Lewis" <jlewis at>
> >The trouble is, it turns out there are a number of networks where
> >CIDR isn't spoken.  They get their IP space from their RIR, break
> >it up into /24s, and announce those /24s (the ones they're using
> >anyway) into BGP as /24s with no covering CIDR.
> IMHO, such networks are broken and they should be filtered.  If people 
> doing this found themselves unable to reach the significant fraction of the 
> Net (or certain key sites), they would add the covering route even if they 
> were hoping people would accept their incompetent/TE /24s.

	well, your assumptio n about how prefixes are used might be 
	tempered with the thought that some /24s are used for 
	interconnecting ISP's at exchanges...

	and for that matter it seems a lazy ISP to pass the buck 
	on "routability" to an org that runs no transit infrastructure.
	RIR's (Well ARIN anyway) has NEVER assured routability of
	a delegated prefix.  Tracking /filters based on RIR delegation
	policy seems like a leap to me...


> Stephen Sprunk         "God does not play dice."  --Albert Einstein

More information about the NANOG mailing list