Pitfalls of annoucing /24s

Thu Oct 16 03:59:37 UTC 2003

This is a part of the problem.  I realize that large ISPs are probably
against micro-assignments so that they can continue to use address space
to treat customers as indentured servants.  I guess they can skip
Chicago and just filter out any micro-assignments that ARIN may one day
issue.  

My biggest gripe on this topic is about ISPs that assign /24's to
multi-homed customers, but filter out /24's received from peers.  Verio
(the example of the day) accepts /24's (that they likely assigned) from
customers but filters these out from others.  Are they expecting their
peers not to filter these /24's or do they really care?  I suppose if
their peers adopt filtering policies such as theirs, they can just tell
their customers "We accept your /24, but the other guy is filtering it
out"

Michael

-----Original Message-----
From: Andrew Dul [mailto:andrew.dul at quark.net] 
Sent: Wednesday, October 15, 2003 11:35 PM
To: Forrest; michael at awtechnologies.com
Cc: nanog at merit.edu
Subject: RE: Pitfalls of annoucing /24s

Forrest, 

Even if ARIN passes this policy that will not make any provider change
their filtering policy.  It is true that many providers do use the ARIN
allocation sizes to create their filtering rules but the two are not
inherently linked.  Any ASN can choose the filter on what ever rule set
they choose.

Andrew

At 04:38 PM 10/15/2003 -0500, Forrest wrote:
>
>
>This is just one of the many reasons why we need ARIN proposal 2002-3
to 
>be approved.  So that small networks that wish to multihome don't have 
>issues with networks filtering out their /24 along with all the other 
>garbage /24's that are announced.  
>
>http://www.arin.net/policy/2002_3.html
>
>If you support 2002-3 I urge you to get on the ARIN Public Policy 
>Mailing List (PPML) and voice your opinion.
>
>http://www.arin.net/mailing_lists/index.html
>
>Forrest
>
>
>-----Original Message-----
>From:	H. Michael Smith, Jr. [SMTP:michael at awtechnologies.com]
>Sent:	Wednesday, October 15, 2003 4:24 PM
>To:	'Phil Rosenthal'; 'John Palmer'
>Cc:	nanog at merit.edu
>Subject:	RE: Pitfalls of annoucing /24s
>
>
>
>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)? 
>
>Although it may be rare that a large aggregate would become unreachable
>to a "large" network, doesn't the possibility exist that a customer
with
>a /24 would become unreachable (to some) due to the aggregate dropping
>out even though the /24 should still be reachable?  That scenario may
>not be very likely, but the question of assymetric routing and one's
>ability to balance traffic become issues.  Assigning a lower preference
>to /24's would be a lot friendlier than just throwing them away.
>
>If I am way off base, I fully expect to be corrected (with volume).  My
>flame retardant suit is in place.
>
>Michael
>
>-----Original Message-----
>From: owner-nanog at merit.edu [mailto:owner-nanog at merit.edu] On Behalf Of
>Phil Rosenthal
>Sent: Wednesday, October 15, 2003 4:47 PM
>To: John Palmer
>Cc: nanog at merit.edu
>Subject: Re: Pitfalls of annoucing /24s
>
>
>http://info.us.bb.verio.net/routing.html#PeerFilter
>
>That's how Verio does it, and I assume, that's how most people who 
>filter by length do it as well.
>
>--Phil
>On Oct 15, 2003, at 4:40 PM, John Palmer wrote:
>
>>
>> Good question.
>>
>> You know there are thousands of legacy /24's out there that were 
>> allocated by
>> IANA as /24's How can you aggregate them up if all you have is the
>/24?
>>
>> To those who filter out /24's - how is this done - just by the
netmask
>
>> size?
>>
>> ----- Original Message -----
>> From: "Jean-Christophe Smith" <jsmith at vitalstream.com>
>> To: <nanog at merit.edu>
>> Sent: Wednesday, October 15, 2003 15:34
>> Subject: Pitfalls of annoucing /24s
>>
>>
>>>
>>>
>>> In current practice would there be serious jeopardy of portions of
>the
>>> internet not being able to reach this address space due to bgp 
>>> filters or
>>> other restrictions? What is the smallest acceptable block of IPs
that
>
>>> can be
>>> announced without adverse or unpredictable results? Verio would most

>>> likely
>>> be picking up these routes from us. I don't want to cause a
religious
>>> debate, but I am interested in what the industry consensus is.
>>>
>>> I'm just doing some research, any comments would be appreciated.
>>>
>>> Thanks,
>>> Jean-Christophe Smith
>>>
>>>
>>
>>
>--Phil Rosenthal
>ISPrime, Inc.
>
>
>
>
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>