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?
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