[64073] in North American Network Operators' Group
RE: Pitfalls of annoucing /24s
daemon@ATHENA.MIT.EDU (H. Michael Smith, Jr.)
Wed Oct 15 18:08:28 2003
From: "H. Michael Smith, Jr." <michael@awtechnologies.com>
To: "'Phil Rosenthal'" <pr@isprime.com>
Cc: <nanog@merit.edu>, "'John Palmer'" <nanog@adns.net>
Date: Wed, 15 Oct 2003 18:05:01 -0400
In-Reply-To: <B3F9235672C543459FF9783503CC54B301A2029C@cauexch01.cau.edu>
Errors-To: owner-nanog-outgoing@merit.edu
Understood. But... networks filtering out the /24 announcement will
always prefer the aggregate learned from the owner/issuer of the space.
They'll be completely unaware that another route exists to the (/24)
network. If the customers link to the provider that assigned the space
goes down, those filtering /24's will still send the traffic to the
'owner' of the space (right?).
What is the issuer of the /24 is filtering incoming /24 advertisements
(Verio)? Will they learn the route to the other ISP or blackhole
traffic destined for their own customer?
I keep hoping that I am missing something here. If not, I sure hope
more folks don't adopt Verio's filtering techniques. (I know that a
VERY low AS # issues /24's out of a /8)
-----Original Message-----
From: Phil Rosenthal [mailto:pr@isprime.com]
Sent: Wednesday, October 15, 2003 5:42 PM
To: H. Michael Smith, Jr.
Cc: nanog@merit.edu; 'John Palmer'
Subject: Re: Pitfalls of annoucing /24s
On Oct 15, 2003, at 5:24 PM, H. Michael Smith, Jr. wrote:
>
>
> What about the /24's that many ISPs (especially tier 2-3) are
assigning
> to multi-homed customers? What about an IX or "critical
infrastructure
> providers" that may be issued a /24 from ARIN (Policy 2001-3)?
>
As long as it's provider assigned, and your provider announces the
supernet that the /24 is from, it will still work. If you announce PI
space out of the old class A space in /24's, many networks wont be able
to reach you.
