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Re: The Gorgon's Knot. Was: Re: Verio Peering Question
From: Vadim Antonov <avg () exigengroup com>
Date: Fri, 28 Sep 2001 17:00:59 -0700 (PDT)

To set the record straingt --

by the time Sprint instituted filtering policy, it had no AGS+es in the
core.  Incidentally, Sprint was the first ISP to start deplyoing 7000s
(and discovering bugs in those - the instability caused by the forced
installation of the "latest and greatest" didn't make customers very

The reason for being very sensitive about routing tables was that ICM part
of things had quite arcane routing policies; and ability of AS1800 boxes
to process updates in a timely fashion was quite vital for keeping
US-Europe Internet connectivity up and running.

Marketing at that time was so clueless about Internet that they couldn't
even pronounce "routing filter", and definitely couldn't make a marketing
blitz out of it.


On Fri, 28 Sep 2001, Sean Donelan wrote:

On Fri, 28 Sep 2001, Sean M. Doran wrote:
| I also encouraged all other backbones to filter Verio as Verio filters them.

FWIW, I (continue to) encourage this too.   Filter more than Verio,
while you're at it.

I used to filter on both inbound and outbound.  I don't believe
filtering is inherently evil.  I believe just the opposite, it
is frequently necessary.  Especially in a world where you can't
verify route announcements and people occasionally announcing
every disaggreated network in the table.

Sprint had valid reasons for filtering.  They had several old AGS
routers, and didn't want to/couldn't upgrade them at the time to
one of the routers used by other backbone providers i.e. 7000/SSP.
To keep Sprint's network working, they filtered routes.  This is
an acceptable example of duct tape we've all needed to apply to
our networks at one time or another to keep everything tied together.

What annoyed me isn't the technical decision, but the marketing
blitz used to justify it as "saving the Internet."

No sales guy wants to say "because our routers can't handle the full
routing table."  Instead you get the revolving wheel of excuses like
  1) Because we are saving the Internet (false)
  2) Because ARIN/RIPE/APNIC makes us (false)
  3) Because our peering agreements require it (false)
Notice how it is always some third-party "forcing" them to do it.

If you want to save the Internet, filter both inbound and outbound.
Otherwise, don't pretend that's why you are doing it.

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