<div dir="ltr">I have a policy applied to my upstreams and peers to deny the IXP's LANs were connected to. I don't think of any reason to learn these routes from someone else's network.</div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, Mar 27, 2019 at 7:44 PM Cummings, Chris <<a href="mailto:ccummings@coeur.com">ccummings@coeur.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
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<div>Not too sure about your topology, but I’ve had something similar bite me, so we typically put a prefix list inbound to deny receiving our internal prefixes from our peers. This probably doesn’t work as well if your network is less “eyeballish” than ours,
however. </div>
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<div style="direction:ltr">/chris</div>
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<div class="gmail_quote">On Wed, Mar 27, 2019 at 4:37 PM -0500, "Graham Johnston"
<span dir="ltr"><<a href="mailto:johnstong@westmancom.com" target="_blank">johnstong@westmancom.com</a>></span> wrote:<br>
<br>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
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<div class="gmail-m_-1260747795496204870WordSection1">
<p class="MsoNormal">This afternoon at around 12:17 central time today we began learning the subnet for the Equinix IX in Chicago via a transit provider; we are on the IX as well. The subnet in question is <a href="http://208.115.136.0/23" target="_blank">208.115.136.0/23</a>. Using
<a href="https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fstat.ripe.net&c=E,1,HdSVqYeR7jgCV-Dur66y05aHEW-BSduVIIHYHrXZ1P6qOt3fa684wgoFR9CoVMgOpEaWMO0lwDjZkSR-n80nd7Rvcqp4MKodaGyrIDIjEhtPXiDie1SaYsyZJ9ed&typo=1" target="_blank">
stat.ripe.net</a> I can see that this subnet is also being learned by others, see the snip below. On our network this caused a nasty routing loop until we figured out what was wrong. My current best understanding is that because the route was learned via eBGP
it trumped the OSPF learned route. As soon as I filtered the advertisement from my transit provider everything returned to normal. What am I doing that isn’t best practices that would have prevented this?<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Thanks,<u></u><u></u></p>
<p class="MsoNormal">graham<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">RIPE Info<u></u><u></u></p>
<p class="MsoNormal" style="background:rgb(252,252,252)"><strong><span style="font-size:10pt;font-family:Helvetica,sans-serif;color:rgb(28,66,87);border:1pt solid rgb(221,221,221);padding:3pt;background:rgb(228,228,228)">1</span></strong><span class="gmail-m_-1260747795496204870jqtreecommon"><span style="font-size:10pt;font-family:Helvetica,sans-serif;color:rgb(28,66,87);border:1pt solid rgb(221,221,221);padding:3pt;background:rgb(228,228,228)"> RRCs
see </span></span><strong><span style="font-size:10pt;font-family:Helvetica,sans-serif;color:rgb(28,66,87);border:1pt solid rgb(221,221,221);padding:3pt;background:rgb(228,228,228)">1</span></strong><span class="gmail-m_-1260747795496204870jqtreecommon"><span style="font-size:10pt;font-family:Helvetica,sans-serif;color:rgb(28,66,87);border:1pt solid rgb(221,221,221);padding:3pt;background:rgb(228,228,228)"> peers
announcing </span></span><strong><span style="font-size:10pt;font-family:Helvetica,sans-serif;color:rgb(28,66,87);border:1pt solid rgb(221,221,221);padding:3pt;background:rgb(228,228,228)"><a href="http://208.115.136.0/23" target="_blank">208.115.136.0/23</a></span></strong><span class="gmail-m_-1260747795496204870jqtreecommon"><span style="font-size:10pt;font-family:Helvetica,sans-serif;color:rgb(28,66,87);border:1pt solid rgb(221,221,221);padding:3pt;background:rgb(228,228,228)"> originated
by <a href="https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fstat.ripe.net%2fAS32703&c=E,1,TOo4BxuZBilA6dEeEsyArFdQvYciFoXF4XjZNU4NqyzUFPawLd-3hzV5XwlwfBLIcVRBns_GfdJCxNBaU2dYqDWisxgCxwxRPMoTfXq-TRSDQa_BgAvqRg,,&typo=1" title="Query RIPEstat for AS32703 (IFN-NET - Indiana Fiber Network)" target="_blank"><b><span style="color:rgb(255,146,74)">AS32703</span></b></a></span></span><span style="font-size:10pt;font-family:Helvetica,sans-serif;color:rgb(51,51,51)"><u></u><u></u></span></p>
<p class="gmail-m_-1260747795496204870jqtreecommon1" style="margin-right:6pt;margin-bottom:3pt;margin-left:15pt;background:rgb(252,252,252)">
<span style="font-size:10pt;font-family:Symbol;color:rgb(51,51,51)"><span>·<span style="font:7pt "Times New Roman"">
</span></span></span><span style="font-size:10pt;font-family:Helvetica,sans-serif;color:rgb(51,51,51)">▼</span><span class="gmail-m_-1260747795496204870rrc-index-0"><span style="font-size:10pt;font-family:Helvetica,sans-serif;color:rgb(28,66,87);border:1pt solid rgb(221,221,221);padding:3pt;background:rgb(228,228,228)">RRC00
in </span></span><strong><span style="font-size:10pt;font-family:Helvetica,sans-serif;color:rgb(28,66,87);border:1pt solid rgb(221,221,221);padding:3pt;background:rgb(228,228,228)">Amsterdam, Netherlands</span></strong><span class="gmail-m_-1260747795496204870rrc-index-0"><span style="font-size:10pt;font-family:Helvetica,sans-serif;color:rgb(28,66,87);border:1pt solid rgb(221,221,221);padding:3pt;background:rgb(228,228,228)"> sees </span></span><strong><span style="font-size:10pt;font-family:Helvetica,sans-serif;color:rgb(28,66,87);border:1pt solid rgb(221,221,221);padding:3pt;background:rgb(228,228,228)">1</span></strong><span class="gmail-m_-1260747795496204870jqtreecommon"><span style="font-size:10pt;font-family:Helvetica,sans-serif;color:rgb(28,66,87);border:1pt solid rgb(221,221,221);padding:3pt;background:rgb(228,228,228)"> ASN
orginating </span></span><em><span style="font-size:10pt;font-family:Helvetica,sans-serif;color:rgb(28,66,87);border:1pt solid rgb(221,221,221);padding:3pt;background:rgb(228,228,228)"><a href="http://208.115.136.0/23" target="_blank">208.115.136.0/23</a></span></em><span class="gmail-m_-1260747795496204870jqtreecommon"><span style="font-size:10pt;font-family:Helvetica,sans-serif;color:rgb(28,66,87);border:1pt solid rgb(221,221,221);padding:3pt;background:rgb(228,228,228)">.</span></span><span class="gmail-m_-1260747795496204870info"><span style="font-size:7.5pt;font-family:Helvetica,sans-serif;color:rgb(102,102,102);border:1pt solid rgb(221,221,221);padding:3pt;background:rgb(228,228,228)">AS32703</span></span><span style="font-size:10pt;font-family:Helvetica,sans-serif;color:rgb(51,51,51)"><u></u><u></u></span></p>
<p class="gmail-m_-1260747795496204870jqtreecommon1" style="margin-right:12pt;margin-bottom:3pt;margin-left:30pt;background:rgb(252,252,252)">
<span style="font-size:10pt;font-family:"Courier New";color:rgb(51,51,51)"><span>o<span style="font:7pt "Times New Roman"">
</span></span></span><span style="font-size:10pt;font-family:Helvetica,sans-serif;color:rgb(51,51,51)">▼</span><strong><span style="font-size:10pt;font-family:Helvetica,sans-serif;color:rgb(28,66,87);border:1pt solid rgb(221,221,221);padding:3pt;background:rgb(228,228,228)"><a href="https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fstat.ripe.net%2fAS32703&c=E,1,LPjxozPn3-dGOA9bDJB081OscbzusnfrxssBxyMbOyunZUcNyeibk_RHV8UYO3Fw77TpLU9yRsywr6KjrmyXWgKk4DQ7XRSgr1_W1SNgkfA,&typo=1" title="Query RIPEstat for AS32703 (IFN-NET - Indiana Fiber Network)" target="_blank"><span style="color:rgb(255,146,74)">AS32703</span></a></span></strong><span class="gmail-m_-1260747795496204870jqtreecommon"><span style="font-size:10pt;font-family:Helvetica,sans-serif;color:rgb(28,66,87);border:1pt solid rgb(221,221,221);padding:3pt;background:rgb(228,228,228)"> is
seen as the origin by </span></span><strong><span style="font-size:10pt;font-family:Helvetica,sans-serif;color:rgb(28,66,87);border:1pt solid rgb(221,221,221);padding:3pt;background:rgb(228,228,228)">1</span></strong><span class="gmail-m_-1260747795496204870jqtreecommon"><span style="font-size:10pt;font-family:Helvetica,sans-serif;color:rgb(28,66,87);border:1pt solid rgb(221,221,221);padding:3pt;background:rgb(228,228,228)"> peer.</span></span><span class="gmail-m_-1260747795496204870info"><span style="font-size:7.5pt;font-family:Helvetica,sans-serif;color:rgb(102,102,102);border:1pt solid rgb(221,221,221);padding:3pt;background:rgb(228,228,228)">192.102.254.1</span></span><span style="font-size:10pt;font-family:Helvetica,sans-serif;color:rgb(51,51,51)"><u></u><u></u></span></p>
<p class="gmail-m_-1260747795496204870jqtreecommon1" style="margin-right:18pt;margin-bottom:3pt;margin-left:45pt;background:rgb(252,252,252)">
<span style="font-size:10pt;font-family:Wingdings;color:rgb(51,51,51)"><span>§<span style="font:7pt "Times New Roman"">
</span></span></span><span style="font-size:10pt;font-family:Helvetica,sans-serif;color:rgb(51,51,51)">▼</span><strong><span style="font-size:10pt;font-family:Helvetica,sans-serif;color:rgb(28,66,87);border:1pt solid rgb(221,221,221);padding:3pt;background:rgb(228,228,228)"><a href="https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fstat.ripe.net%2f192.102.254.1&c=E,1,fW5rffxlYLANo-g3GopSdMyHH2oIqoulMERJOjPrrdRL4Z8602v0WhaVuS6ignBPzPDgh4S05V55mLAGu_OFn1TzFyYcCpMMzTgH1ejtJmILMrcaDQDn&typo=1" title="Query RIPEstat for 192.102.254.1" target="_blank"><span style="color:rgb(255,146,74)">192.102.254.1</span></a></span></strong><span class="gmail-m_-1260747795496204870jqtreecommon"><span style="font-size:10pt;font-family:Helvetica,sans-serif;color:rgb(28,66,87);border:1pt solid rgb(221,221,221);padding:3pt;background:rgb(228,228,228)"> is
announcing route <a href="https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fstat.ripe.net%2fAS395152&c=E,1,I_iMCTImXK-T7Vj5VALSLMN6lo0N3-N2qYG7QlBHNK8oXNmPQnsp4zJy424NN2Y8z2WxSBIfaPSkLoibtnClWliVcGMhdMDsIewEnAgiZaRITyPjKA,,&typo=1" title="Query RIPEstat for AS395152 (CLOUDPBX-VAN - CloudPBX)" target="_blank"><b><span style="color:rgb(255,146,74)">AS395152</span></b></a> <a href="https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fstat.ripe.net%2fAS63297&c=E,1,V7oySywzIc8rSc64KXotimJVgetH1G5VqJoedNuNjm9JbOYDh8qrdMlVKD12tKJtJ4STBfu9kLFuBXInbfko44ryiCz5Gy2CztDGyYXF4HJW6Jm3uPvJgOUAfTc,&typo=1" title="Query RIPEstat for AS63297 (PACIFIC-SERVERS - Pacific Servers Inc.)" target="_blank"><b><span style="color:rgb(255,146,74)">AS63297</span></b></a> <a href="https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fstat.ripe.net%2fAS6327&c=E,1,4wIITl8037dr3SSHzQmbAIwgiFe3X75-DkFAlERAGWEFjFROhFPMC2c3IGy_vChkNN-YI2OoobMvhOUKjiV9mt69N8kXl_RTvv22nZHKLJkYc59V&typo=1" title="Query RIPEstat for AS6327 (SHAW - Shaw Communications Inc.)" target="_blank"><b><span style="color:rgb(255,146,74)">AS6327</span></b></a> <a href="https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fstat.ripe.net%2fAS36280&c=E,1,_jAHKYzgyGwMDV4H1HRk1FK3bV5j_t6dSn2YfYhnhLBYub5v33-ryduZ34KVZYUy19lhSRThf8TUnUT_6V35nTMLw6SCXqY0S8bggDBKvYUg&typo=1" title="Query RIPEstat for AS36280 (-Reserved AS-)" target="_blank"><b><span style="color:rgb(255,146,74)">AS36280</span></b></a><a href="https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fstat.ripe.net%2fAS32703&c=E,1,RAfxFbCQUejEFosUxg2dek9Ke5qatnE5GGjP6p2ovv1XL6hN77GlayI0Nm5jA_jRLCxzzaZQUdABGyy7HlA7bi93SIbytUbKx_49kJPC168,&typo=1" title="Query RIPEstat for AS32703 (IFN-NET - Indiana Fiber Network)" target="_blank"><b><span style="color:rgb(255,146,74)">AS32703</span></b></a>.</span></span><span style="font-size:10pt;font-family:Helvetica,sans-serif;color:rgb(51,51,51)"><u></u><u></u></span></p>
<div style="border:1pt solid rgb(204,204,204);padding:7pt;background:whitesmoke;margin-left:42pt;margin-right:24pt">
<pre style="margin-left:18pt;background:whitesmoke;border:none;padding:0cm;box-sizing:border-box;border-radius:4px;white-space:pre-wrap;overflow:auto"><span style="font-family:Wingdings;color:rgb(51,51,51)"><span>§<span style="font:7pt "Times New Roman""> </span></span></span><span style="font-family:Consolas;color:rgb(51,51,51)">Origin: IGP<u></u><u></u></span></pre>
<pre style="margin-left:18pt;background:whitesmoke;border:none;padding:0cm"><span style="font-family:Wingdings;color:rgb(51,51,51)"><span>§<span style="font:7pt "Times New Roman""> </span></span></span><span style="font-family:Consolas;color:rgb(51,51,51)">Next Hop: 192.102.254.1<u></u><u></u></span></pre>
<pre style="margin-left:18pt;background:whitesmoke;border:none;padding:0cm"><span style="font-family:Wingdings;color:rgb(51,51,51)"><span>§<span style="font:7pt "Times New Roman""> </span></span></span><span style="font-family:Consolas;color:rgb(51,51,51)">Peer: 192.102.254.1<u></u><u></u></span></pre>
<pre style="margin-left:18pt;background:whitesmoke;border:none;padding:0cm"><span style="font-family:Wingdings;color:rgb(51,51,51)"><span>§<span style="font:7pt "Times New Roman""> </span></span></span><span style="font-family:Consolas;color:rgb(51,51,51)">Community: 63297:1000<u></u><u></u></span></pre>
<pre style="margin-left:18pt;background:whitesmoke;border:none;padding:0cm"><span style="font-family:Wingdings;color:rgb(51,51,51)"><span>§<span style="font:7pt "Times New Roman""> </span></span></span><span style="font-family:Consolas;color:rgb(51,51,51)">AS Path: 395152 63297 6327 36280 32703<u></u><u></u></span></pre>
<pre style="margin-left:18pt;background:whitesmoke;border:none;padding:0cm"><span style="font-family:Wingdings;color:rgb(51,51,51)"><span>§<span style="font:7pt "Times New Roman""> </span></span></span><span style="font-family:Consolas;color:rgb(51,51,51)">Last Updated: 2019-03-27T17:17:19<u></u><u></u></span></pre>
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<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Route-views<u></u><u></u></p>
<p class="MsoNormal"><a href="https://linkprotect.cudasvc.com/url?a=https%3a%2f%2froute-views.chicago.routeviews.org&c=E,1,E0igNv77g9AAa2d6Uaxl8p-e1C0XIX7IzMRDUURg85DkFqIFTzckgumVyHoZqhybvGEz7rGGqi_cSc8KzJW5xx3nxdSBkfe6z_hdXiip8re7qfTpyjS1o2wzcvLw&typo=1" target="_blank">route-views.chicago.routeviews.org</a>>
show ip bgp 208.115.136.0<u></u><u></u></p>
<p class="MsoNormal">BGP routing table entry for <a href="http://208.115.136.0/23" target="_blank">208.115.136.0/23</a><u></u><u></u></p>
<p class="MsoNormal">Paths: (1 available, best #1, table Default-IP-Routing-Table)<u></u><u></u></p>
<p class="MsoNormal"> Not advertised to any peer<u></u><u></u></p>
<p class="MsoNormal"> 32709 32703<u></u><u></u></p>
<p class="MsoNormal"> 208.115.136.134 from 208.115.136.134 (63.134.128.248)<u></u><u></u></p>
<p class="MsoNormal"> Origin IGP, localpref 100, valid, external, best<u></u><u></u></p>
<p class="MsoNormal"> AddPath ID: RX 0, TX 64414249<u></u><u></u></p>
<p class="MsoNormal"> Last update: Wed Mar 27 17:16:09 2019<u></u><u></u></p>
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