[132014] in North American Network Operators' Group
Re: AS path question.
daemon@ATHENA.MIT.EDU (Jon Lewis)
Wed Nov 10 21:36:00 2010
Date: Wed, 10 Nov 2010 21:35:50 -0500 (EST)
From: Jon Lewis <jlewis@lewis.org>
To: Scott Weeks <surfer@mauigateway.com>
In-Reply-To: <20101110172546.1F7DDF7A@resin05.mta.everyone.net>
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Wed, 10 Nov 2010, Scott Weeks wrote:
> Why did that make you feel safe? Other than a bug, and ignorance of
> BGP, what is unsafe about a lotta prepends?
Ignorance of BGP? There's a known cisco bug that causes BGP session
resets when as as-path length exceeds 255. I've been running with bgp
maxas-limit 75 for years as a "just in case there are other bugs & I find
it very hard to believe anyone legitimately needs an as-path length
anywhere near that long". Worst case, someone is silly with their number
of prepends, we don't see their route. I can't say how long I've been
doing this...it predates our rancid setup, which means >6 years. Though
it's caused numerous dropped routes, it hasn't generated a single
complaint.
In your opinion, is filtering of BGP routes based on prefix length also a
sign of ignorance? Everyone should just be letting all the crap through?
----------------------------------------------------------------------
Jon Lewis, MCP :) | I route
Senior Network Engineer | therefore you are
Atlantic Net |
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