Scott Weeks wrote:

--- drc@virtualized.org wrote: On Oct 8, 2007, at 2:48 PM, Scott Weeks wrote:

...

However, if it's less than a /24 it won't get very far as most upstreams block prefixes longer than a /24.

I'm curious: a couple of people have indicated they do not believe this to be the case. Anybody have any hard data on what filters are actually in use today? --------------------------------------------

I found two current policies. Other companies made it too hard to find...

Sprint: # Customers may announce routes as small as /26 for ARIN IP address blocks obtained through Sprint. Customers may announce routes as small as /28 for RIPE and APNIC address blocks obtained through Sprint.

# Peer block announcements and customer announcements for blocks obtained from other providers are limited to a /24 or smaller mask (/23, /22 etc.).

AT&T: * not accept Customer route announcements smaller than a /24 network

Level3:

From the output of whois -h rr.level3.net AS3356 <snip> remarks: The following import actions are common to every remarks: Level 3 non-customer peering session: remarks: remarks: - RFC1918 and other reserved networks and subnets are remarks: not permitted. remarks: remarks: - Advertisements with reserved ASes in the path remarks: (ie 64512 - 65535) are not permitted. remarks: remarks: - Prefixes shorter than /8 or longer than /24 are remarks: not permitted. <snip>

(the rest is useful reading too if you deal with level3 much) Vince

scott