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.
On Wed, Mar 27, 2019 at 7:44 PM Cummings, Chris <ccummi...@coeur.com> wrote: > 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. > > /chris > > > > On Wed, Mar 27, 2019 at 4:37 PM -0500, "Graham Johnston" < > johnst...@westmancom.com> wrote: > > 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 208.115.136.0/23. Using >> stat.ripe.net >> <https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fstat.ripe.net&c=E,1,HdSVqYeR7jgCV-Dur66y05aHEW-BSduVIIHYHrXZ1P6qOt3fa684wgoFR9CoVMgOpEaWMO0lwDjZkSR-n80nd7Rvcqp4MKodaGyrIDIjEhtPXiDie1SaYsyZJ9ed&typo=1> >> 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? >> >> >> >> Thanks, >> >> graham >> >> >> >> >> >> RIPE Info >> >> *1* RRCs see *1* peers announcing *208.115.136.0/23 >> <http://208.115.136.0/23>* originated by *AS32703* >> <https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fstat.ripe.net%2fAS32703&c=E,1,TOo4BxuZBilA6dEeEsyArFdQvYciFoXF4XjZNU4NqyzUFPawLd-3hzV5XwlwfBLIcVRBns_GfdJCxNBaU2dYqDWisxgCxwxRPMoTfXq-TRSDQa_BgAvqRg,,&typo=1> >> >> · ▼RRC00 in *Amsterdam, Netherlands* sees *1* ASN orginating >> *208.115.136.0/23 >> <http://208.115.136.0/23>*.AS32703 >> >> o ▼*AS32703 >> <https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fstat.ripe.net%2fAS32703&c=E,1,LPjxozPn3-dGOA9bDJB081OscbzusnfrxssBxyMbOyunZUcNyeibk_RHV8UYO3Fw77TpLU9yRsywr6KjrmyXWgKk4DQ7XRSgr1_W1SNgkfA,&typo=1>* >> is >> seen as the origin by *1* peer.192.102.254.1 >> >> § ▼*192.102.254.1 >> <https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fstat.ripe.net%2f192.102.254.1&c=E,1,fW5rffxlYLANo-g3GopSdMyHH2oIqoulMERJOjPrrdRL4Z8602v0WhaVuS6ignBPzPDgh4S05V55mLAGu_OFn1TzFyYcCpMMzTgH1ejtJmILMrcaDQDn&typo=1>* >> is >> announcing route *AS395152* >> <https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fstat.ripe.net%2fAS395152&c=E,1,I_iMCTImXK-T7Vj5VALSLMN6lo0N3-N2qYG7QlBHNK8oXNmPQnsp4zJy424NN2Y8z2WxSBIfaPSkLoibtnClWliVcGMhdMDsIewEnAgiZaRITyPjKA,,&typo=1> >> *AS63297* >> <https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fstat.ripe.net%2fAS63297&c=E,1,V7oySywzIc8rSc64KXotimJVgetH1G5VqJoedNuNjm9JbOYDh8qrdMlVKD12tKJtJ4STBfu9kLFuBXInbfko44ryiCz5Gy2CztDGyYXF4HJW6Jm3uPvJgOUAfTc,&typo=1> >> *AS6327* >> <https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fstat.ripe.net%2fAS6327&c=E,1,4wIITl8037dr3SSHzQmbAIwgiFe3X75-DkFAlERAGWEFjFROhFPMC2c3IGy_vChkNN-YI2OoobMvhOUKjiV9mt69N8kXl_RTvv22nZHKLJkYc59V&typo=1> >> *AS36280* >> <https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fstat.ripe.net%2fAS36280&c=E,1,_jAHKYzgyGwMDV4H1HRk1FK3bV5j_t6dSn2YfYhnhLBYub5v33-ryduZ34KVZYUy19lhSRThf8TUnUT_6V35nTMLw6SCXqY0S8bggDBKvYUg&typo=1> >> *AS32703* >> <https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fstat.ripe.net%2fAS32703&c=E,1,RAfxFbCQUejEFosUxg2dek9Ke5qatnE5GGjP6p2ovv1XL6hN77GlayI0Nm5jA_jRLCxzzaZQUdABGyy7HlA7bi93SIbytUbKx_49kJPC168,&typo=1> >> . >> >> § Origin: IGP >> >> § Next Hop: 192.102.254.1 >> >> § Peer: 192.102.254.1 >> >> § Community: 63297:1000 >> >> § AS Path: 395152 63297 6327 36280 32703 >> >> § Last Updated: 2019-03-27T17:17:19 >> >> >> >> >> >> Route-views >> >> route-views.chicago.routeviews.org >> <https://linkprotect.cudasvc.com/url?a=https%3a%2f%2froute-views.chicago.routeviews.org&c=E,1,E0igNv77g9AAa2d6Uaxl8p-e1C0XIX7IzMRDUURg85DkFqIFTzckgumVyHoZqhybvGEz7rGGqi_cSc8KzJW5xx3nxdSBkfe6z_hdXiip8re7qfTpyjS1o2wzcvLw&typo=1>> >> show ip bgp 208.115.136.0 >> >> BGP routing table entry for 208.115.136.0/23 >> >> Paths: (1 available, best #1, table Default-IP-Routing-Table) >> >> Not advertised to any peer >> >> 32709 32703 >> >> 208.115.136.134 from 208.115.136.134 (63.134.128.248) >> >> Origin IGP, localpref 100, valid, external, best >> >> AddPath ID: RX 0, TX 64414249 >> >> Last update: Wed Mar 27 17:16:09 2019 >> >
