Re: ip prefix-list rfc1918-dsua - "Documenting Special Use

This could be considered "good" practice, but not "best" practice. The
actual list that should be used for non-valid routes on the Internet is
known as the Bogon list, which can be found here:
http://www.cymru.com/Documents/bogon-bn.html. The problem with using
RFC 3330 is that it is no longer accurate. For example, 24.0.0.0/8 is
listed in 3330 as special use, but now it is available for normal
allocation.

Brian McGahan, CCIE #8593 (R&S/SP/Security)
bmcgahan_at_INE.com <mailto:bmcgahan_at_INE.com>
 
Internetwork Expert, Inc.
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Rich Collins wrote:
> Hello,
>
> I've been revisiting this topic which has been brought up many times
> in one form or another on this list. Today I stumbled upon a
> reference to a Cisco document with this prefix list.
>
> It is a general purpose prefix list meant for external BGP peerings.
> I understand that this prefix lists includes the RFC1918 range and
> other special purpose address ranges but not full RFC 3330. I take it
> to mean that this list is "good practice".
>
>
> ip prefix-list rfc1918-dsua deny 0.0.0.0/8 le 32
> ip prefix-list rfc1918-dsua deny 10.0.0.0/8 le 32
> ip prefix-list rfc1918-dsua deny 127.0.0.0/8 le 32
> ip prefix-list rfc1918-dsua deny 169.254.0.0/16 le 32
> ip prefix-list rfc1918-dsua deny 172.16.0.0/12 le 32
> ip prefix-list rfc1918-dsua deny 192.0.2.0/24 le 32
> ip prefix-list rfc1918-dsua deny 192.168.0.0/16 le 32
> ip prefix-list rfc1918-dsua deny 224.0.0.0/4 le 32
> ip prefix-list rfc1918-dsua permit 0.0.0.0/0 le 32
>
> Should it include the Class E deny 240.0.0.0/4 possibly? Otherwise
> does it look accurate and make sense to memorize (versus a longer list
> such as RFC3330)?
>
> -Rich
>
>
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Received on Thu May 21 2009 - 15:03:21 ART