<div dir="ltr">I've been bit by this in the past at two different exchanges.  I too have a policy applied to deny IXP LANs from upstreams and peers.  It would be nice if there was a list of all IXP LANs somewhere that we could generically add to all upstream and peers.<div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, Mar 28, 2019 at 9:11 AM Eric Dugas <<a href="mailto:edugas@unknowndevice.ca">edugas@unknowndevice.ca</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,204,204);padding-left:1ex"><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" target="_blank">ccummings@coeur.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,204,204);padding-left:1ex">



<div>


<div style="direction:ltr">
<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>
<div><br>
</div>
<div class="gmail-m_-8839542719538590584gmail-m_-1260747795496204870ms-outlook-ios-signature">
<div style="direction:ltr">/chris</div>
</div>
</div>
<br>
<br>
<br>
<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-width:1px;border-left-style:solid;border-left-color:rgb(204,204,204);padding-left:1ex">
<div dir="3D"ltr"">


<div class="gmail-m_-8839542719538590584gmail-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-color:rgb(252,252,252);background-position:initial initial;background-repeat:initial initial"><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-color:rgb(228,228,228);background-position:initial initial;background-repeat:initial initial">1</span></strong><span class="gmail-m_-8839542719538590584gmail-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-color:rgb(228,228,228);background-position:initial initial;background-repeat:initial initial"> 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-color:rgb(228,228,228);background-position:initial initial;background-repeat:initial initial">1</span></strong><span class="gmail-m_-8839542719538590584gmail-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-color:rgb(228,228,228);background-position:initial initial;background-repeat:initial initial"> 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-color:rgb(228,228,228);background-position:initial initial;background-repeat:initial initial"><a href="http://208.115.136.0/23" target="_blank">208.115.136.0/23</a></span></strong><span class="gmail-m_-8839542719538590584gmail-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-color:rgb(228,228,228);background-position:initial initial;background-repeat:initial initial"> 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_-8839542719538590584gmail-m_-1260747795496204870jqtreecommon1" style="margin-right:6pt;margin-bottom:3pt;margin-left:15pt;background-color:rgb(252,252,252);background-position:initial initial;background-repeat:initial initial">
<span style="font-size:10pt;font-family:Symbol;color:rgb(51,51,51)"><span>·<span style="font-style:normal;font-variant-caps:normal;font-weight:normal;font-stretch:normal;font-size:7pt;line-height:normal;font-family:"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_-8839542719538590584gmail-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-color:rgb(228,228,228);background-position:initial initial;background-repeat:initial initial">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-color:rgb(228,228,228);background-position:initial initial;background-repeat:initial initial">Amsterdam, Netherlands</span></strong><span class="gmail-m_-8839542719538590584gmail-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-color:rgb(228,228,228);background-position:initial initial;background-repeat:initial initial"> 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-color:rgb(228,228,228);background-position:initial initial;background-repeat:initial initial">1</span></strong><span class="gmail-m_-8839542719538590584gmail-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-color:rgb(228,228,228);background-position:initial initial;background-repeat:initial initial"> 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-color:rgb(228,228,228);background-position:initial initial;background-repeat:initial initial"><a href="http://208.115.136.0/23" target="_blank">208.115.136.0/23</a></span></em><span class="gmail-m_-8839542719538590584gmail-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-color:rgb(228,228,228);background-position:initial initial;background-repeat:initial initial">.</span></span><span class="gmail-m_-8839542719538590584gmail-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-color:rgb(228,228,228);background-position:initial initial;background-repeat:initial initial">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_-8839542719538590584gmail-m_-1260747795496204870jqtreecommon1" style="margin-right:12pt;margin-bottom:3pt;margin-left:30pt;background-color:rgb(252,252,252);background-position:initial initial;background-repeat:initial initial">
<span style="font-size:10pt;font-family:"Courier New";color:rgb(51,51,51)"><span>o<span style="font-style:normal;font-variant-caps:normal;font-weight:normal;font-stretch:normal;font-size:7pt;line-height:normal;font-family:"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-color:rgb(228,228,228);background-position:initial initial;background-repeat:initial initial"><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_-8839542719538590584gmail-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-color:rgb(228,228,228);background-position:initial initial;background-repeat:initial initial"> 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-color:rgb(228,228,228);background-position:initial initial;background-repeat:initial initial">1</span></strong><span class="gmail-m_-8839542719538590584gmail-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-color:rgb(228,228,228);background-position:initial initial;background-repeat:initial initial"> peer.</span></span><span class="gmail-m_-8839542719538590584gmail-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-color:rgb(228,228,228);background-position:initial initial;background-repeat:initial initial">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_-8839542719538590584gmail-m_-1260747795496204870jqtreecommon1" style="margin-right:18pt;margin-bottom:3pt;margin-left:45pt;background-color:rgb(252,252,252);background-position:initial initial;background-repeat:initial initial">
<span style="font-size:10pt;font-family:Wingdings;color:rgb(51,51,51)"><span>§<span style="font-style:normal;font-variant-caps:normal;font-weight:normal;font-stretch:normal;font-size:7pt;line-height:normal;font-family:"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-color:rgb(228,228,228);background-position:initial initial;background-repeat:initial initial"><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_-8839542719538590584gmail-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-color:rgb(228,228,228);background-position:initial initial;background-repeat:initial initial"> 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-color:whitesmoke;margin-left:42pt;margin-right:24pt;background-position:initial initial;background-repeat:initial initial">
<pre style="margin-left:18pt;background-color:whitesmoke;border:none;padding:0cm;box-sizing:border-box;border-top-left-radius:4px;border-top-right-radius:4px;border-bottom-right-radius:4px;border-bottom-left-radius:4px;white-space:pre-wrap;overflow:auto;background-position:initial initial;background-repeat:initial initial"><span style="font-family:Wingdings;color:rgb(51,51,51)"><span>§<span style="font-style:normal;font-variant-caps:normal;font-weight:normal;font-stretch:normal;font-size:7pt;line-height:normal;font-family:"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-color:whitesmoke;border:none;padding:0cm;background-position:initial initial;background-repeat:initial initial"><span style="font-family:Wingdings;color:rgb(51,51,51)"><span>§<span style="font-style:normal;font-variant-caps:normal;font-weight:normal;font-stretch:normal;font-size:7pt;line-height:normal;font-family:"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-color:whitesmoke;border:none;padding:0cm;background-position:initial initial;background-repeat:initial initial"><span style="font-family:Wingdings;color:rgb(51,51,51)"><span>§<span style="font-style:normal;font-variant-caps:normal;font-weight:normal;font-stretch:normal;font-size:7pt;line-height:normal;font-family:"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-color:whitesmoke;border:none;padding:0cm;background-position:initial initial;background-repeat:initial initial"><span style="font-family:Wingdings;color:rgb(51,51,51)"><span>§<span style="font-style:normal;font-variant-caps:normal;font-weight:normal;font-stretch:normal;font-size:7pt;line-height:normal;font-family:"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-color:whitesmoke;border:none;padding:0cm;background-position:initial initial;background-repeat:initial initial"><span style="font-family:Wingdings;color:rgb(51,51,51)"><span>§<span style="font-style:normal;font-variant-caps:normal;font-weight:normal;font-stretch:normal;font-size:7pt;line-height:normal;font-family:"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-color:whitesmoke;border:none;padding:0cm;background-position:initial initial;background-repeat:initial initial"><span style="font-family:Wingdings;color:rgb(51,51,51)"><span>§<span style="font-style:normal;font-variant-caps:normal;font-weight:normal;font-stretch:normal;font-size:7pt;line-height:normal;font-family:"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>
</div>
<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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