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Here is a doc for each hardware vendor for filtering long as paths. Not sure if this will help you or if the issue is before filtering takes place. </div>
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We have ours max length set to 75.</div>
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<a rel="noreferrer noopener" href="https://bgpfilterguide.nlnog.net/guides/long_paths/">https://bgpfilterguide.nlnog.net/guides/long_paths/</a><br>
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Erik</div>
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<div style="direction: ltr;">Erik Sundberg</div>
<div style="direction: ltr;">Sr. Network Engineer</div>
<div style="direction: ltr;">Nitel</div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> NANOG <nanog-bounces+esundberg=nitelusa.com@nanog.org> on behalf of Scott Weeks <surfer@mauigateway.com><br>
<b>Sent:</b> Friday, March 4, 2022 8:46:47 PM<br>
<b>To:</b> nanog@nanog.org <nanog@nanog.org><br>
<b>Subject:</b> Re: RU evidently hijacked UA netblock</font>
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<br>
--- jay@west.net wrote:<br>
On 3/4/22 18:03, Scott Weeks wrote:<br>
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> It looks like a 'too many' AS prepends, but it is only 250 prepends.<br>
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In most reasonable scenarios I'd say that this qualifies as too many.<br>
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Yeah, technically, but it was not 256 or something where I'd expect an issue to happen. Just curious as to why only that ASN caused the buffer overflow messages as I got them from no other AS ever and wondered if anyone else has seen them. Other ASNs almost
certainly have sent 250+ prepends to me before, but they did not cause the overflow. Like I said, I have a ticket open because I am curious:<br>
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BGP-WARNING-tBgp4RouteInvalid-2007 <stuff> Route invalid reason - Cannot add/prepend AS-path. Buffer overflow\nNRLI - <prefix> where prefixes are several and different lengths.<br>
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Probably nothing, but I always look into stuff I see in the syslog server's router.log.<br>
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scott<br>
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